Importantly, rather than resting on an inverse farm size – productivity relationship, policy that seeks to impact both equity and efficiency should focus on ensuring that smallholders have access to the productivity gains experienced by their larger counterparts. Thus, policies that help build human capital, facilitate adoption of new technologies, and enhance access to markets via a reduction in transactions costs will continue to be indispensable for reducing rural poverty in developing countries.The regularity with which an inverse relationship between farm size and land productivity is observed led to many theoretical explanations for the phenomenon. Early explanations centered around multiple market failures , asymmetric information , and risk aversion among farmers . A second set of explanations emphasized empirical issues such as systematic measurement error in farm size and/or output and omitted variables . Empirical studies have typically found that existing theory fails to fully explain the observed inverse relationship, generating a body of mixed and at times contradictory evidence. Chapter 1 illustrates how the choice of productivity measure can alter the relationship observed and how it can obscure a changing relationship between farm size and total factor productivity, the more relevant productivity measure. A dynamic relationship was found between farm size and total factor productivity in the rapidly modernizing agricultural regions of Brazil, contributing to an emerging literature that documents changing farm size – productivity relationships as agricultural sectors modernize and develop . This is consistent with Helfand et al. , hydroponic bucket whose findings suggest that both the larger commercial farms and smaller family farms in Brazil have advantages in harnessing technical change and achieving rapid gains in productivity.

In this paper the hypothesis of a dynamic farm size – productivity relationship is extended to the context of Mexico, identifying the relationship in a panel of family farms from the Mexican Family Life Survey and testing for changes over the sample period of 2002-2009. Mexico is an interesting case for assessing changes in the farm size – productivity relationship because of its long history of land reform and the recent agricultural policy reform associated with the North American Free Trade Agreement in the 1990s. These policies are a prime example of the Washington Consensus, liberalizing markets for land, agricultural inputs, and agricultural output in Mexico with the objective of spurning the modernization, competitiveness, and productivity of the agricultural sector and the broader economy. An environment with such market reforms, if successful, is expected to diminish the multiple market failure explanation of the inverse relationship between farm size and productivity, and any observed inverse relationship might weaken accordingly. We test for changes in the farm size – productivity relationship and, contrary to expectations, find that an inverse relationship exists and has remained strong in the wake of Mexico’s market reforms. We explore the relationship further by estimating a stochastic production frontier, an approach often applied in developed economy agriculture but infrequently applied in developing economy contexts. While frontier productivity growth has increased rapidly for larger farms, eliminating the inverse relationship at the frontier, the average relationship has remained unchanged due to more rapidly increasing technical inefficiency amongst the larger farms in the sample. This finding highlights the need for, and echoes calls for, policies that support family farms’ transitions towards modern agriculture and adaptation to market liberalization in Mexico.

The proceeding section discusses agricultural policy in Mexico, providing context for the empirical analysis. This is followed by an introduction of the empirical methodology, a description of the data, and the presentation of empirical results. Policy recommendations for Mexican agriculture and research implications conclude.The institutional structure of Mexican agriculture continues to reflect agricultural policies implemented after the Mexican Revolution of the early 20th century. Land policy of the 1934 Agrarian Code established the ejidos – tracts of communally held land with individual plots farmed by designated households – as a principle tool for redistributing land and property rights to peasants. Agrarian communities, a distinct form of land tenure located predominantly in the South where farmers had pre-existing claims to agricultural land, were similarly formed although to a lesser extent. A dual system of agricultural tenure emerged, with ejido farmers on the one hand and private landowners on the other. Within both the ejido and private farm sectors there exists both the larger, commercially oriented farms and the smaller predominantly subsistence farms. It is in this context that Berry and Cline first studied the farm size – productivity relationship in Mexico. Drawing from the Mexican Agricultural Census of 1940 and of 1960, they compared land productivity of small and large private farms. They found land productivity of small farms to be 6.5 times larger than that of larger farms in 1940, but just 3.5 times as large by 1960. More importantly, when output per unit of land and capital was measured, a more comprehensive measure of productivity, small farms were 1.7 times more productive than large farms in 1940 but just 0.8 times as productive in 1960. This early evidence illustrates that an inverse relationship between farm size and land productivity is neither necessary nor sufficient for an inverse relationship between farm size and more comprehensive productivity measures, similar to the findings of chapter 1 in the context of Brazil.

Berry and Cline hypothesized that the changing productivity ratios reflected a shift from livestock to crops on large farms, facilitated by government investment in infrastructure, provision of credit, and other supportive policies. As the birthplace of the Green Revolution, Mexican agriculture experienced productivity growth throughout this period, notably becoming net exporters of important staples such as wheat and maize. A weakening of the IR between farm size and land productivity accompanied this period of agricultural modernization and development, as did a reversal of the IR between farm size and output per unit of capital and labor. More recent research using farm-level panel data from the Mexico National Rural Household Survey , a household survey statistically representative of 80% of rural Mexico, showed evidence of an inverse relationship between farm size and productivity in 2003 and 2008 . By estimating an average production function and a stochastic production frontier, they find an inverse relationship between farm size and land productivity, farm size and average TFP, and farm size and TFP along the production frontier. They conclude that the observed farm size – TFP relationship was driven, in part, by larger farms being further from the frontier . Mexican agriculture in the early 20th century is an interesting setting for studying the farm size – productivity relationship because of the policy changes and market reforms associated with The North American Free Trade Agreement going into effect in 1994. As part of an economy-wide reduction in tariffs, agricultural tariffs were gradually eliminated over a 14-year span ending in 2008. The liberalization of agricultural trade exposed the Mexican agricultural sector to increased competition and imports from Northern neighbors. As a result, a flood of cheap imports has led to a decline in the price of staple crops for many Mexican farmers . For Mexican agriculture, NAFTA was part of a broader program of reform and market liberalization. One important change was the Program for the Certification of Ejido Rights and Titling of Urban Plots , which included reform of the ejido system of land tenure. Following a constitutional amendment, Procede facilitated the new option for ejidos to privatize individual parcels that could then be mortgaged, rented, or sold. Further, agricultural rights to ejido parcels ceased being contingent upon actual agricultural production, strengthening property rights for the ejido sector. Importantly for the private sector, stackable planters the practice of expropriating large private holding for the formation of ejidos was ended. By securing property rights and integrating ejidos into the market, these changes were expected to increase opportunities throughout the rural farm sector. A World Bank evaluation of the ejido reforms found that, while Procede had been widely successful in securing property rights, often in the form of certificates of agricultural rights, the program had not led to widespread land transfers and ejido farms remained credit constrained at the turn of the century. A second set of policy changes affected the manner in which government supported agricultural input and output markets. Policy shifted away from heavily subsidizing inputs and providing price supports for output towards a system of direct transfers for those impacted by increased international competition. In general, producers of staple products have suffered due to increased competition with relatively cheap imports whereas exports of high-valued horticultural products have benefited . The Program for Direct Assistance in Agriculture , primarily an income support program, offered per hectare payments to any farms with a history of producing any of nine key staples prior to 1993 that were actively farming one of those crops. An important change to the program in 1995 allowed participation of any farm producing any legal crop that had previously qualified for the program.

Further changes to the program in 2001 included higher per-hectare payments for farms under 5 hectares and a shift of the timing of payments to the start of the planting season. Alongside Procampo is Alianza para el Campo, a suite of programs designed to increase agricultural productivity primarily through investment in infrastructure and extension assistance. As government programs withdrew, farms became increasingly reliant upon markets for access to key agricultural inputs such as fertilizer, pesticides, and seed and for access to credit. Although government credit programs have scaled back, well functioning credit markets have not appeared in rural Mexico and access to credit markets is not widespread, inhibiting access to key inputs and modern technology. As in other developing country contexts, market concentration in both input markets and post harvest processing and marketing has hurt the profitability of family farms and generated economies of scale in transacting with the agricultural supply chain. We hypothesize that the farm size – TFP relationship is likely to be changing over time in the wake of Mexico’s NAFTA-era reforms, much as it appears to have done in Mexico during the Green Revolution and in Brazil’s modernizing agricultural regions . This hypothesis rests upon the assumptions that market imperfections contribute to any pre-existing IR in Mexican agriculture and Mexico’s NAFTA-era market liberalization has improved the efficiency of agricultural input and output markets. Beyond the farm size – productivity relationship, agricultural productivity is important to Mexico for both rural economic development and poverty reduction. According to data from the World Bank,2 agricultural output made up 3.6% of Mexico’s GDP but employed 13-14% of the workforce in 2015. Further, approximately62% of Mexico’s rural population is impoverished when using the national poverty line, suggesting that agricultural productivity has a potentially important role in Mexico’s rural economic development and efforts to reduce poverty. There are similar implications for trends in migration, as increasing agricultural productivity on family farms facilitates the ability to generate adequate livelihoods and effectively support families, reducing an important push factor in migration decisions.As discussed in chapter 1, land productivity is a partial measure of productivity and does not account for the use of inputs other than land. Where other inputs are used in production, failing to account for the use of those resources potentially introduces bias into estimates of the relationship between farm size and productivity if the intensity of input use varies with farm size. Controlling for all inputs in agricultural production can be accomplished with estimation of a production function, uncovering TFP, the comprehensive and preferable measure of productivity. We use two complementary approaches to explore the relationship between farm size and TFP with a panel of Mexican farms. First, we use an average production function to estimate average TFP and its relationship with farm size. Second, we use a stochastic production frontier to estimate both TFP along the technological frontier and technical inefficiency, identified as deviations from the frontier. The frontier analysis identifies any relationship between farm size and frontier TFP and any relationship between farm size and technical inefficiency. As is standard in the literature , we view TFP change as a combination of changes in the technological frontier and changes in the deviations from the frontier.

The removal of underripe berries was also evident by the difference in color among treatments. For BA, the rejected treatments were significantly lighter in color; however, the color of the sort and control treatments was very similar, whereas a similar trend was observed in the CS treatments. Wines made from GN generally did not follow these trends; possibly because sorting parameters were too aggressive for this cultivar, resulting in a high percent rejection of optimal berries. This may have minimized potential differences between reject wine with the other treatments. Another possibility is that color differences in the GN fruit did not correspond to differences in sugar content. From these results, it may be concluded that, when using color as a criterion, optical sorting based on ripeness level was successful but may be dependent on variety and fruit variability. Additionally, the impact on the resulting wine is likely dependent on the initial variability in grape ripeness. The optical sorter was successful in removing MOG. This result was reflected in the phenolic analyses; reject treatments were generally higher in total phenolics and tannin, most likely due to the greater proportion of MOG included in the must. The decrease in anthocyanins is likely due to the higher percentage of green, underripe berries in the reject treatment musts. A study that made wine with the addition of MOG found that this addition significantly increased the phenolic and tannin content in the resulting wines. Despite the differences observed in the phenolic composition of the reject wines, the control and sort treatments were very similar for all three varieties. This is in contrast with some previous studies that have found wine made from optical sorted fruit had significantly different levels of phenolics. One study found that optical sorting led to wines with higher levels of total phenolics. It should be mentioned that the researchers here did whole cluster pressing for their control wines , hydroponic nft system whereas the sorted wines were destemmed. It is possible that higher levels of phenolics were extracted due to the damage caused by the destemming process on the seeds and skins.

Another study found that wine made from optically sorted grapes that were machine harvested generally had lower levels of phenolics; levels that were similar to the same wines made from a handpick treatment. Given that the rejects were, in general, significantly higher in total phenolics and tannin than the control and sort treatments, it can be suggested that optical sorting has the potential to decrease the phenolic content in wine; however, there was not enough MOG to show a large impact in the current study. Optical sorting likely has a greater impact on mechanically harvest fruit due to generally higher levels of MOG observed from this harvest method. Some differences were found among treatments in the aroma profiles of the wines. Few compounds differed significantly between sort and control treatment and, in general, the reject treatments had greater concentrations of higher alcohols and control and sort treatments had greater concentrations of ethyl esters. The higher ethanol content of the sort and control treatments as well as their lower pH can lead to a higher production of esters. In general, reject treatments contained significantly more suspended solids then the control and sort treatments for all varieties studied. Research has shown that high levels of suspended solids during fermentation can lead to greater production of higher alcohols. Descriptive analysis indicated only one significantly different attribute among GN treatments and only two significantly different attributes among BA treatments. BA control and sort wines were associated with the “alcohol” descriptor which correlated with the higher ethanol levels in these treatments compared to the reject treatment. Similarly, there were only three significant attributes among the CS treatments. “Alcohol hotness” related to ethanol content as previously described. The control and sort treatments were also rated significantly higher in “apple” and “sweet” aromas compared to the reject treatment.

Some studies have shown that higher levels of ethanol can increase the perception of sweetness in a wine. However, as King et al. noted, there is disagreement in this regard, as other studies have shown that ethanol content can either decrease or have no effect on the perception of sweetness. Thus, this may not be a sufficient explanation as to why the control and sort wines were rated significantly higher in sweetness. Perhaps the higher concentration of total phenolics and tannin in reject wines could explain the difference given that phenolics in wine contribute to bitterness and astringency. From the PCA in Figure 6, it can be noted that “bitter” and “drying” are more associated with reject wines. Although these attributes are not significantly different among the treatments there appears to be a trend which could impact the perception of sweetness. It is possible that reject wines were rated lower in “sweet” due to the higher concentration of phenolic compounds thus decreasing the perception of sweetness. The higher perception of sweetness in the control and sort wines may also be attributed to the higher intensity of the “apple” aroma, which the judges could have associated with a sweet taste. One study found that retronasal aromaperception of fruity compounds increased with an increasing level of sweetness in a model wine solution. The authors also noted several other studies which found that aroma compounds can enhance the perception of sweetness in different foods and beverages. Another study found that samples described as “fruity” were also often associated with a “sweet” aroma. This provides further evidence that the judges in the current study may have associated these attributes together. The overall sensory differences were minimal, and the wines were determined to be similar. The results from this study largely agree with results from previous studies investigating the effects of optical sorters. It is possible that there was not enough variation in the starting material of the current study for optical sorting to have a large impact. Optical sorters may be used to greater effect during vintages with inconsistent ripening, issues with raisining, or large amounts of berry damage, possibly caused by either birds and/or fungal infections. Future research should investigate the impact of optical sorters in these scenarios. Keeping It Living developed from the content and discussions surrounding the 1997 American Association for the Advancement of Science symposium entitled “Was the Northwest Coast of North America ‘Agricultural’?: Aboriginal Plant Use Reconsidered.”

It is a compilation of exceptional work done by many scholars who have studied Northwest Coast Native communities from Oregon to Southeast Alaska. In each chapter, the authors present evidence from historic accounts and oral histories describing the management of plants for improved productivity. The long-standing construct is that Northwest Coast populations did not practice plant cultivation and instead relied almost exclusively on harvesting of marine resources and gathering of native fruits for sustenance. The book’s editors and contributing authors challenge this perspective. They suggest that the common view is based on the assumptions codified in the historical accounts from the seventeenth and eighteenth centuries and perpetuated by many anthropologists who visited with community members in the nineteenth and twentieth centuries. Although archaeological studies have provided plenty of evidence for the antiquity of Northwest Coast fishing practices, climate conditions in this region are not adequate for the preservation of plant remains. As such, there is no physical evidence of the history of indigenous horticultural or agricultural management. In light of this dilemma, the authors approach the subject from an ethnographic standpoint, utilizing past accounts and modern perspectives to reconstruct plant management by the indigenous peoples from Oregon to Southeast Alaska. The authors deftly organize the ethnographic evidence describing harvesting, seed collection, planting, and cultivation practices used by indigenous communities in this region. More than three hundred indigenous plants used by these communities are described and/or listed in this volume. In the introduction, nft channel the editors identify the need for a reconstruction of our understanding of indigenous resource management. The rest of the chapters are separated into two groups: concepts and case studies. In the first of the five concept chapters, Bruce D. Smith describes how the historic characterization of the Northwest Coast peoples as “affluent hunter gatherers” was based on the mistaken assumption that these people were not using agricultural techniques to enhance the productivity of useful indigenous plants. He calls into question the dualistic perspective that communities are either hunter-gatherers or agriculturalists. In the next chapter, Kenneth M. Ames describes the evolutionary intensification of food production systems in the Northwest Coast and elsewhere. He identifies food storage as essential for the development of the social complexity observed in these sedentary communities and offers a perspective on the implications of increased food production in complex hunter-gatherer societies. In chapter 4, Nancy J. Turner and Sandra Peacock provide a broad overview of the nature of peopleplant interactions in these communities and present some specific examples of plant resource management. Next they describe the “continuum” of indigenous plant-management activities practiced by these communities. In the concept section’s last chapter, Turner, Robin Smith, and James T. Jones describe ownership patterns for the plant resources used, illustrating how each group developed its own system of ownership based on environmental and cultural factors. The second section offers informative case studies of plant use from numerous Northwest Coast areas. Wayne Suttles describes the ownership, management, and harvest of camus bulbs by the Coast Salish. Their management techniques included loosening the soil, weeding out grasses, transplanting, and burning above ground vegetation after harvest.

Early ethnographers used the terms semiagricultural and protohorticultural to describe these practices. Suttles suggests that the cultivation of camus may have been described as protohorticultural because lilies were common in European flower gardens at the time of contact. Melissa Derby describes how precontact Chinook villages of the Lower Columbia River were situated adjacent to the wetlands where the wapato grew. She makes the case that the level of social complexity of the Chinookan people is related to their management of wapato as an agricultural commodity. Dana Lepofsky and her colleagues present direct and indirect evidence for the use of controlled burning in indigenous agroecosystems in British Columbia’s Fraser Valley. Next, James McDonald uses historical documents to describe how the Tsimshian managed horticultural plants for food production. For example, an account from 1859 documents the members of this community farming “potato” . Other visitors observed plant management for the harvest of berries, crab apples, maplewood, ferns , hemlock bark and sap, lichen, devils club, and skunk cabbage. Remarkably, the individuals who described community ownership of specific berry patches simultaneously maintained the view of the Tsimshian lands as an unmanaged wilderness. McDonald is the only author who states the obvious: it benefits the colonizers to perpetuate this myth because it enables them to justify the appropriation of the land on the grounds that it is in need of management. In chapter 10, Madonna Moss describes Tlingit horticulture in Southeast Alaska, the northernmost portion of the Northwest Coast. Moss characterizes the Tlingits’ precontact management of indigenous plants as a system of selective harvesting. The exception was tobacco, which was grown prior to European contact using the horticultural management techniques of seeding, weeding, and fertilizing. She proposes that it was their expertise with tobacco that enabled these people to raise the horticultural crops introduced in the eighteenth century successfully. In the final case study, Douglas Deur describes the creation and maintenance of estuarine gardens by indigenous communities. Keeping it Living is a shining example of scientific reevaluation and concentrated inquiry of a long-held perspective, and it is as necessary as it is exemplary. Litigation involving Indian claims in the modern era often revolves around the complex and expensive reports prepared by ethnohistorians, historians, anthropologists, and other experts. Any claim involving the meaning of a treaty provision or whether a tribe qualifies for gaming on lands acquired after 1988 or even whether a tribe should be federally recognized will involve this battle of experts. Tribal victories in the Sioux Nation’s Black Hills land claim, Pacific Northwest and Great Lakes treaty fishing rights, and eastern land claims would have been unobtainable without careful expert testimony.

We calculated daily energy requirements for birds under field conditions as M =  2.5, where W is the weight of an average insectivorous bird on coffee farms . We calculated the weight of an average insectivorous bird by averaging body masses of 33 insectivorous resident and migrant bird species reported to consume CBB on Jamaican and Costa Rican coffee farms , or predicted to consume CBB based on morphology and diet breadth . Sherry et al. found that CBB made up 5%–10% of the diet of three Neotropical migratory warblers by number of individuals consumed; we used these percentages to estimate how many calories, and therefore how many CBB, birds potentially eat. Avian consumption rate of CBB was constant, with even effort across the coffee season. For avian densities, we used estimates from Karp et al. of 3 to 14 birds per ha, because these densities include known CBB predators on coffee farms in Costa Rica.Parameters for our Leslie matrix for coffee berry borers are broadly consistent with expectations and general knowledge . For example, our conversion of fecundity to a daily value, F1 = 1.341, is consistent with published literature stating that 1–2 eggs are laid per day by CBB . Model projections showed that across a 185-day CBB breeding period starting at the point of first ovipositing, an initial population size of 100 female dispersers would produce 1.3 million offspring, resulting in a new adult population of 70,245 females . Assuming  99% of colonizing females successfully bore and oviposit in a coffee cherry on Day 0, the first generation of new dispersing females does not appear until day 37. At Day 38, the adult population begins to increase, and continues to do so exponentially.The daily growth rate of this population converged on 1.042. Sensitivity analysis revealed that survival of adult females had the largest impact on overall population growth , followed by daily survival of pupa , juveniles , eggs and larvae and dispersing females . In addition to modeling growth with 100 initial colonists , grow bag for tomato we projected the population growth of low and high starting populations calculated from observed weekly alcohol-lure trap catches during peak dispersal .

Comparing the three population projections, peak number of dispersers at Day 185 varied considerably, with 162, 3259, and 8768 daily dispersers for low, medium, and high colonizing populations, respectively. In the high population projection, the adult population toward the end of the growing season reached over 18,800 individuals. Note that because these are density-independent models, the number of CBB does not depend on plant density. However, the impacts of the CBB population on yield would depend on coffee plant density. To reduce the final adult population by 50%, the daily survival rate of dispersing females would have to be reduced from 0.99602 to 0.83202. This change represents a 16.4% reduction in daily survival when dispersing. The number of CBB that birds need to eat to reduce the adult population at this rate was driven by the initial population size as a straight line, y = 79.23 N0 . At medium starting population , birds need to consume 7628 CBB during the borer breeding season, while at high starting population , about 20,500 dispersing CBB must be consumed by birds. Daily consumption rates by birds would have to increase over time as the CBB population grows and could vary from 15 to 750 CBB being consumed a day, depending on starting population size . Overall, we calculated that for every female CBB in the initial colonization, birds need to consume 79 CBB to reduce the end of season population by half.We estimated that the caloric content of a 195 μg adult CBB to be 1.09 calories per gram dry weight, or 0.00109 kcal. At 5%–10% of a bird’s daily diet based on number of prey items, birds would consume <7 CBB per day. This represents 0.03%–0.05% of daily caloric requirements of our average insectivorous bird. At these feeding rates, our models suggest that by the time of peak dispersal, 4, 88, and 236 birds are required at low, medium, and high starting population sizes, respectively, to reduce CBB populations by 50% on day 185 .Our model suggests that avian predation is likely to be effective at reducing CBB populations by 50% only during small infestations , or during the early stages of larger infestations .

Birds appear unable to successfully suppress medium and large infestations because the number of CBB that need to be eaten in a season requires higher bird densities than are reported in the literature. Karp et al. estimated 4–12 birds/ha of species that are confirmed or suspected CBB predators. Flocks of migratory birds on coffee farms are estimated at 19/ha and 24/ha , but these values are also short of our estimates of necessary densities for suppressing larger CBB outbreaks. One caveat to our conclusions is that our calculations were based on CBB accounting for 5%–10% of a bird’s daily diet . This assumption meant birds would only eat a set maximum of 7 CBB per day. Sherry et al. reported up to 116 CBB in the stomach contents of a single warbler, suggesting under certain circumstances in the field, birds eat more CBB. Generalist insectivores, particularly Neotropical migrants, have flexible foraging preferences and would likely feed opportunistically on CBB in response to dramatic dispersal peaks. Therefore, birds might be expected to increase feeding rates as CBB disperser abundances increase, though it may depend on the relative abundances of other prey. Better data on CBB consumption rates by birds under different circumstances would improve our estimates of the circumstances under which birds can control CBB populations. A second caveat is that bird densities used in the model may not represent the potential for CBB control because bird densities depend on the structure of the agricultural landscape, which the current model does not consider. On coffee farms, birds are more abundant when native tree cover is highest and natural forests are close by . Across tropical and temperate regions, the propensity for birds to forage on farms, and thus exert pressure on agricultural pests, is correlated with the physical complexity and diversity of the agroecosystem . For example, birds make more frequent foraging trips to apple orchards with high native tree coverage . In alfalfa fields, edge habitat complexity supports greater avian richness leading to lower pest abundances . Under some circumstances, the density of birds foraging in certain areas may behigher than average densities would imply, leading to greater control potential than our models suggest.

More generally, our CBB population model is density independent and assumes environmental conditions and sufficient resources to allow CBB populations to increase without restriction. As a result, our model is limited, as it does not consider localized effects of weather and temperature fluctuations on CBB developmental time , nor characteristics of coffee farms that influence both CBB infestation and bird density. We assumed maximal capacity for CBB population growth and used estimates of bird densities from the literature that only included birds known to consume CBB, perhaps underestimating the potential for avian control. Models are an important tool for estimating population dynamics, but as with any species, the growth potential for CBB and availability of its predators, is context dependent. Our study echoes Kendall et al.’s conclusion that, grow bag for blueberry plants even though errors in model construction are common, these seldom change qualitative conclusions. From our population matrix, CBB daily growth rate converged on λdaily = 1.042 around day 124, with an observed rate of population change across the entire coffee-growing season of 705 . Our λdaily is higher than Mariño et al.’s reported lambda of 1.32 over  50– 56 days, which corresponds to λdaily ≈ 1.006 . Part of this discrepancy may come from the fact that Marino et al. combined vital rates across life stages with different time steps. Nonetheless, both models are consistent in predicting rapidly growing populations. Observed CBB population growth rates are similar to ours: Baker, Barrera, & Rivas, calculated a 1.067 growth rate in wild populations and RuizCardenas and Baker reported 1.047 in CBB reared in laboratory settings. In their sensitivity analysis, Mariño et al. reported that adult female survival, and transitions from larva to pupa and pupa to juvenile had high sensitivity in contributing to population growth rate, with adult survival the highest . We found a similar peak sensitivity value for female adult survival in our matrix , supporting the idea that CBB population growth is most sensitive to adult survival rate. Interestingly, dispersal survival from our matrix was estimated to have low impact on population growth , even though this life stage is when CBB are vulnerable to bird predation. Thus, our analysis superficially suggests that population control once CBB are established should focus on reducing adult survival rather than on trapping dispersing females , if the same impact on numbers could be achieved. However, dispersing females are much more accessible to control methods like spraying fungal bioinsecticide than are adult females, which are inside the coffee cherries, so despite the tremendous difference in sensitivity values, management of an established population is likely to be more cost effective by continuing to focus on dispersing females . Population models specific to CBB have been criticized for not being representative of wild populations, since more generations are estimated through modeling than are observed in field studies . We analyzed CBB population growth using a deterministic model, with an even distribution of dispersal and a fixed predation pressure. While CBB dispersal is continuous, there can be dramatic intraseasonal peaks in numbers that were not captured by our model . In addition, reported longevity of female CBB varies widely from 55 to 380 days, though some studies looked at CBB reared on artificial diet . Refinements of survival in natural settings would, therefore, improve models of CBB population growth, and the potential for control by birds. If field data on CBB vital rate stochasticity become available, and bird densities opportunistically increase during CBB peak numbers, it could affect our conclusions about the capacity of birds to control larger CBB outbreaks. Based on our analyses, there is a population density of CBB above which their capacity to produce more adults exceeds the ability of birds to control their numbers, at least to limit the population size by 50%. This positive density-dependent relationship between population growth and density is an Allee effect , and escape from predation is one mechanism for this phenomenon . In general, predator-driven Allee effects can occur when predators are the main driver of prey dynamics and when predators are generalists as are insectivorous Neotropical migrants . Additionally, predators can exert strong pressure when prey availability is not temporally or spatially limited—a potential limiting factor in the coffee system, since CBB are only available to birds during dispersal. Variation in starting population size is likely dependent on how recently CBB have colonized in an area, timing of trapping , the size of the farm , and the extent to which farmers used control measures the previous year . We found that only under very low initial population sizes of CBB could birds be expected to suppress pest numbers by 50%. We note that earlier, stronger CBB suppression by birds would lead to lower infestation numbers later in the coffee season, but this might require selective foraging by birds, depending on relative abundances of other prey species. In conclusion, our models suggest that birds can control CBB under some circumstances, depending on the relative size of the starting CBB population and existing local bird density. To put this idea into practice it is important to remember that managing farms for bird habitat does not always result in pest reduction. Birds may not prey on the pest of interest or birds might cause pest numbers in increase by preying on insect predators that normally regulates the pest population . Aside from predators, pest species are also impacted by the agricultural environment directly . In fact, on coffee farms where bird densities are higher in shade, CBB infestations are also higher , possibly because CBB native range is in humid, shade forests of Africa . It is important that future modeling include such habitat-specific factors to understand Our research helps quantify the densities under which birds have the potential to control CBB populations.

The molecular underpinnings of color variation and fruit shape in Fragaria are mostly unknown or unreported, although clearly of interest for development of molecular markers for breeding purposes to meet changing consumer tastes. In strawberry, antioxidant compounds such as polyphenols and ascorbic acid are important nutritional traits. Yet these are difficult traits to assess as they are influenced not only by genotype, but by the growing environment and by developmental stage. Forexample, levels of the bio-active nonflavonoid polyphenol, ellagic acid , is higher in achenes from ripe fruit of the F. vesca cultivar Yellow Wonder than in achenes from ripe fruit of F. × ananassa cultivar Calypso. A complication for improving fruit nutrient quality is that EA levels are higher in achenes than in receptacles of all cultivars tested, and EA is found primarily at small green stage. In addition, the mode of inheritance of EA content is yet to be elucidated. Previously unidentified bio-active compounds, such as the acylphloroglucinol glucosides discovered in F. × ananassa while examining the enzymatic properties of recombinant F. vesca chalcone synthases, may also exist in Fragaria species. With the availability of modern methods in metabolomics and allied fields, discovery of additional bio-active compounds is likely, and these methods can be applied to direct molecular approaches to improving fruit quality. In the future, metabolic flux analysis should also enhance our ability to delineate what biochemical pathways are good targets for fruit quality improvement as well and to predict what modifications may influence fruit quality parameters.There has been ample progress in recent years in describing the genetic architecture of disease resistance in cultivated strawberry. Many resistances appear to be primarily conferred by one or two major loci or large-effect QTL, including to Phytophthora fragariae, Xanthomonas fragariae, Phytophthora cactorum, Fusarium oxysporum f.sp fragariae, Colletotrichum gloeosporoides, and Colletotrichum acutatum.

For P. cactorum, additional minor loci have recently been identified. On the other hand, resistances to Verticillium dahaliae and Podosphaera aphanis appear to be quite complex, grow bag with no major loci identified to date. This suggests that genomic prediction approaches for these two diseases would be most effective. However, with the advent of the “Camarosa” genome, an opportunity exists to characterize Mildew Locus O genes in strawberry toward potential gene editing solutions. Elucidating the genetics of resistance to M. phaseolina should be a high priority in the future, given the recent spread of this pathogen in important production regions and the lack of effective controls for this disease. In addition, no resistance genes have been reported against gray mold caused by Botrytis cinerea. Instead, it seems most likely that any small differences in tolerance to this disease among cultivars results from morphological variations in flower structures, fruit firmness, etc. Because strong resistance to B. cinerea is not likely to result from conventional breeding, a gene editing solution may be most viable. Where disease resistances are conferred by one or a few genes, genetic and breeding approaches to characterize and increase resistance are straightforward. In the cases where classical R genes are involved, the development of custom-capture libraries and single-molecule resequencing of captured target sequences has been quite effective for identifying causal gene variants. In fact, such a resource has now been developed for cultivated strawberry in the form of a RenSeq library based on the “Camarosa” reference and resequencing of a number of elite cultivars and breeding lines. Combining this resource with mapping and association genetics approaches should help uncover subgenome-specific variants underlying known loci and lead to the cloning of R genes in octoploid strawberry. Given the tremendous allelic diversity present in strawberry and the large copy numbers and highly repetitive coding sequences typical of R genes, assembling long reads from single-molecule realtime sequencing should be helpful to this endeavor. Hand in hand with characterization of R genes, we recommend the characterization of pathogen populations in order to understand the durability of resistances.

The paradigm of a gene-for-gene arms race has been long established, but a more accurate assessment of the durability of resistance could arise from an understanding of the selective forces operating on pathogen effectors. Dual RNA-seq technology can help uncover the dynamic interactions of pathogen and host. Both the pathogen and the host transcriptomes are simultaneously captured and analyzed in silico to distinguish species specific transcripts. For some complex interactions, single cell transcriptomics coupled with protein and metabolite analysis may be helpful. What new insights into disease resistance in strawberry could be gained simply from studying the population structures of causal pathogens? Would identifying and characterizing pathogen effectors give us meaningful insights into the control of pathogens through breeding and other means? It is intriguing that some recently discovered resistance loci in strawberry confer very strong resistances and yet have apparently been durably effective in commercial production for many decades. Cloning the first R genes and pathogen effectors involved these interactions will help us to understand why.The Genome Database for Rosaceae is the central repository and datamining resource for genomics, genetics, and breeding data of Rosaceae, including strawberry and related crops such as almond, apple, apricot, blackberry, cherry, peach, pear, plum, raspberry, and rose. The volume and type of data generated for strawberry research has markedly increased in the past ten years. This includes whole-genome assembly data, RNA-seq data, multiple SNP arrays, increased numbers of QTL, and more genotypic and phenotypic data. The massive volume of data generated by the strawberry research community, combined with active curation, integration, further analyses and tool development by the GDR team has resulted in marked expansion in the data and functionality available for strawberry. In addition to the near-complete chromosome-scale assembly for F. × ananassa, two draft genome assemblies for F. × ananassa are available. Four genome assemblies, including the newest v4.0, are also available for F. vesca. New and much improved annotation v4.0. a2, including 34,007 protein-coding genes with 98.1% complete Benchmarking Universal Single-Copy Orthologs , is available. For older assemblies F. vesca genome v1.1 and v2.0, additional annotations are also available: v1.1.a2 and v2.0.a2, respectively. The draft genome assemblies of four wild diploid Fragaria species and of Potentilla micrantha a species that does not develop fleshy fruit but is closely related to Fragaria, are also available. In addition, the whole genome of F. iinumae has recently become available. GDR now provides a reference transcriptome that combines published RNASeq and EST data sets. The GDR team provides additional computational annotation for both predicted genes of whole-genome assemblies and RefTran datasets with homology to genes of closely related or model plant species and assignment of InterPro protein domains and GO terms. The genome assembly and transcript data can be accessed through the Fragaria genus and species pages, Gene/Transcript search page, JBrowse and BLASTX. The octoploid “Camarosa” genome, F. iinumae v1.0, and both annotation versions of F. vesca Genome v4.0, are used in a synteny analysis with whole-genome assemblies from 18 Rosaceae species using MCScanX with results available to view and search through the Synteny Viewer. GDR hosts 29 genetic maps for Fragaria species, most of which contain trait loci and can be viewed and compared through the MapViewer. Detailed data on 505 QTLs and 5 MTLs for 124 horticultural traits, and 171,115 genetic markers for Fragaria that includes 154,739 SNPs are available, as well as SNP data from the iStraw 90 K array for cultivated strawberry. The SNP data is accessible through JBrowse tracks, downloadable files and can be searched and downloaded from the SNP Marker and All Marker search pages. The Marker search page now includes filtering by trait name, which allows users to search for markers that are near and/or within QTLs using the associated trait name. Phenotyping data from the public projects such as RosBREED are available from GDR. In addition to the “Search Trait Evaluation” page, the public breeding data can be queried and downloaded using the Breeders toolbox.

A new module in GDR, grow bag gardening the Breeding Information Management System , now provides breeders and breeding project teams with tools to easily store, manage, archive and analyze their private or public breeding data. The availability of whole-genome assembly and SNP array data for the cultivated octoploid strawberry, along with wealth of QTL data that are integrated in the community database with data from other related crops are expected to accelerate research and practical tools such as DNA tests. BIMS in GDR will help breeders not only to organize their data but also to utilize the tools and resources that are available for strawberry improvement.The strawberries found in markets around the world today are produced by cultivated strawberry Duchesne ex Rozier, a species domesticated over the past 300 years . F. ananassa is technically not a species but an admixed population of interspecific hybrid lineages between cross-compatible wild allo-octoploid species with shared evolutionary histories . The earliest F. ananassa cultivars originated as spontaneous hybrids between F. chiloensis and F. virginiana in Brittany, the Garden of Versailles, and other Western European gardens in the early 1700s, shortly after the migration of F. chiloensis from Chile to France in 1714 . Their serendipitous origin was discovered by the French Botanist Antoine Nicolas Duchesne and famously described in a treatise on strawberries that biologists suspect included one of the first renditions of a phylogenetic tree . Even though those studies predated both the advent of genetics and the discovery of ploidy differences in the genus, the phylogenies were remarkably close to hypotheses that emerged more than 150 years later . The early interspecific hybrids were observed to be more phenotypically variable than and horticulturally superior to their wild octoploid parents, factors that drove the domestication of F. ananassa. The increase in phenotypic variability can be directly linked to an increase in nucleotide diversity and heterozygosity, and presumably to the introduction of complementary favorable alleles that were not found in either parent. Hardigan et al. showed that hybrids between F. chiloensis and F. virginiana have nearly double the genome-wide heterozygosity of their parents. With the mysterious origin of the spontaneous interspecific hybrids solved , breeding and cultivation shifted to F. ananassa, which supplanted the cultivation of the wild relatives and forever changed strawberry production and consumption worldwide . The romanticized and widely recounted story of the origin of cultivated strawberry, while compelling, oversimplifies the complexity of the wild ancestry and 300-year history of domestication, for which we have an incomplete understanding . One of our motives for reconstructing the genealogy of cultivated strawberry was to shed light on the origin and diversity of the wild founders and the breeding history. The only pedigree-informed studies of the breeding history of cultivated strawberry focused on an analysis of the ancestry of 134 North American cultivars developed between 1960 and 1985 . They identified 53 founders in the pedigrees of those cultivars, estimated that 20 founders contributed approximately 85% of the allelic diversity, and concluded that North American cultivars had originated from a genetically narrow population . Others have reached similar conclusions , and the notion that cultivated strawberry “displays limited genetic variability” has persisted . Gaston et al. were possibly alluding to the absence of morphological diversity on par with that found in tomato . Nevertheless, the genetic narrowness hypothesis has not been supported by genome-wide analyses of DNA variants, which have shown that F. chiloensis, F. virginiana, and F. ananassa harbor massive nucleotide diversity and that a preponderance of the alleles transmitted by the wild octoploid founders have survived domestication and been preserved in the global F. ananassa population . Hardigan et al. proposed an alternative to the “limited genetic variability” hypothesis , arguing that genetic variation has not been reduced by directional selection or population bottlenecks in certain populations. One of the consequences predicted by this hypothesis is the persistence of a high frequency of unfavorable alleles in domesticated populations. The domestication of cultivated strawberry has followed a path different from that of other horticulturally important species, many of which were domesticated over millennia and traced to early civilizations, e.g., apple , olive , and wine grape . Although the octoploid progenitors were cultivated before the emergence of F. ananassa, the full extent of their cultivation is unclear and neither appears to have been intensely domesticated; e.g., Hardigan et al. did not observe changes in the genetic structure between land races and wild ecotypes of F. chiloensis, a species cultivated in Chile for at least 1,000 years .

Policy discussions of the future of small farms, for example, emphasize the role of small farms in agricultural development in part because of their superior efficiency . This argument leans heavily on the inverse farm size – productivity relationship, but requires that small farms be more efficient with their use of all resources and not just land. Whereas a farm size – land productivity relationship does not provide clarity on this issue, a farm size – total factor productivity relationship does. In this light, we argue that the inverse relationship literature needs to shift its focus from land productivity to total factor productivity. In fact, empirical studies assessing the productivity – farm size relationship in the developed world, such as Garcia et al. , Alvarez and Arias , and Rasmussen , almost exclusively use measures of technical efficiency or total factor productivity. Similarly, the literature estimating national level agricultural productivity is clear in its use of total factor productivity as a preferred measure . We illustrate the importance of productivity measures with new empirical evidence on the farm size – productivity relationship across regions of Brazil from 1985 to 2006 . Our evidence is only suggestive because we are unable to correct for potential issues of measurement error in farm size, output, and inputs that have been identified in recent literature. However, this period in Brazil provides an excellent case study because it includes regions with relatively advanced agricultural sectors, those characterized by more traditional agricultural production, and others experiencing rapid agricultural transformation, allowing us to assess the farm size – productivity relationship and its dynamics at different stages of agricultural development. Using a pseudo-panel of farms aggregated at the municipality by farm size level, square black flower bucket we show that estimating the farm size – productivity relationship using land productivity is potentially misleading.

While we always identify an inverse relationship using land productivity, we find disparate results when using total factor productivity. In the modern agricultural regions of Brazil, we find a direct relationship between farm size and total factor productivity, and in the rapidly transforming region of the Center-West we identify dynamics that suggest the inverse relationship is disappearing over time. The analysis highlights that the relationship between total factor productivity and farm size has evolved with modernization, shedding some light on the issues raised by Mill over 150 years ago. The remainder of this paper is organized as follows. In Section 2 we seek to clarify the common measures, their relationships, and their advantages and limitations in empirical work. Section 3 presents the empirical exercise, generating new evidence on the relationship between size and productivity in several macro regions of Brazil. In Section 4 we summarize and conclude with policy implications.Farm size may be related to a broad range of economic outcomes, such as employment, poverty, inequality, food security, efficiency and growth. While these are important issues connected to the role of farm size in development, here, as with most of the literature on the inverse relationship , we focus specifically on the concept of productivity. The following discussion seeks to clarify the relationships between the various productivity measures most commonly used in the literature, allowing us to draw conclusions on the impact that choice of measure may have on finding an IR and the potential implications for policy.The relationship captured by is unconditional in the sense that it is the simple bivariate relationship between land productivity and farm size. Using land productivity as a measure is inherently limited—as would be any partial measure of productivity—whenever there is more than one factor of production.

If use of other factors vary systematically with farm size, the IR between land productivity and farm size may simply reflect more input intensive practices of small farms. Higher land productivity may reflect overuse of fertilizer, for example, which would not necessarily reflect any underlying productivity advantage of small farms. In such situations, estimates of the farm size – land productivity relationship introduces omitted variable bias into estimates of the underlying farm size – productivity relationship. From this perspective, a focus on the relationship between land productivity and the size of farms may be misplaced. Similarly, analysis using different partial productivity measures may result in conflicting policy recommendations. Indeed, Sen’s seminal contribution revealed precisely this type of systematic relationship between the intensity of labor use and farm size, leading to his formal exposition of the dual labor market hypothesis . Figure 1.2 illustrates the problem in the case of Brazil. While there is an inverse relationship between land productivity and farm size, there is a direct relationship between labor productivity and size. Analysis of the farm size and productivity relationship using labor productivity suggests that larger farms are more productive than are their smaller counterparts. Policy recommendations from the two partial measures of productivity would differ, underscoring the need for a comprehensive measure of productivity when identifying any relationship with farm size.We now provide an example using data on Brazilian agriculture. The intention here is not to explain the relationship between farm size and productivity by controlling for its potential determinants. Rather, we seek to use a regional analysis within Brazil to highlight how the choice of measure influences the observed relationship and how these patterns can change across stages of agricultural development. Our evidence is only suggestive because we are unable to correct for the measurement issues in farm size, outputs, and inputs that recent literature has focused on. We discuss this further below. The results provide an important counterpoint to much of the literature that has focused on countries in Africa and Asia where the overwhelming majority of farms have less than 2 hectares . Mean and median farm size in Brazil, in contrast, were around 65 and 10 hectares in 2006. The data come from the 1985, 1995/1996, and 2006 rounds of the Brazilian agricultural census. For confidentiality reasons, we constructed a pseudo-panel in which all farms in the census are aggregated into five farm size classes within each municipality of Brazil.9 Aggregation requires that we assume homogeneity within each observation . We call these “representative-farms,” as they reflect the average behavior of a given farm size in a given municipality. The pseudo-panel approach has been used recently to study agricultural productivity growth by Key and Rada et al. . Antmann and McKenzie demonstrate that, in the context of mobility studies, pseudo-panels can be used to consistently estimate parameters of interest. The averaging within cells in each period reduces the influence of individual-level measurement error, and the fact that it is not a true panel of farms makes it less vulnerable to non-random attrition. They show the approach is also robust to some forms of non-classical measurement error. We begin with 47,365 representative farms for all of Brazil across the three survey years. Due to concern about the comparability of a small number of extremely large observations, square black flower bucket wholesale we remove all representative farms in the Northeast and South over 4,000 ha and all of those over 5,000 ha in the North, Southeast, and Center-West. We then identify land productivity outliers taking into account the IR shown in Figure 1.1 and potential non-linearities. Thus, rather than trim the tails of the unconditional land productivity distribution, we use a quadratic specification to regress land productivity on farm size with municipal fixed effects and survey year dummy variables.

From this regression we identify and remove outliers, defined as all representative farms with residuals greater than four standard deviations from their size specific predicted values. Together, the data cleaning exercises remove 1.8% of the initial sample. The Census data were gathered by the Brazilian Institute of Geography and Statistics through end of season in-person farmer interviews based on recall. Output is measured as the real value of total agricultural production, deflated to 2006 with a price index developed from the data in Gasques et al. . Farm size is measured in hectares , and unlike in many African and Asian countries the overwhelming majority of farms operate a single plot. Additional factors of production used in the production function are family labor, purchased inputs including hired labor, and an index of capital. The number of male, female, and child family members working on each farm are used to develop a family labor index measured in adult male equivalents. The index assigns weights of 1.0 to men, 0.75 to women and 0.5 to children under 14. In 2006 around two thirds of family labor was provided by men, and over 90% of working family members were 14 years or older. The real value of purchased inputs, including expenditure on fertilizer, seeds, hired labor, fuel, energy, soil amendments, and other items, are deflated with the same price index used for output. A proxy for the total capital stock is calculated as a quantity index comprised of machine, animal, and tree capital stock sub-indices following Moreira et al. and Butzer et al. . The machine capital stock index values tractors of five horsepower classes, trucks, harvesters and other agricultural equipment using a constant set of sale prices drawn from the Instituto de Economia Agrícola in São Paulo. The stock of animal capital is measured in cattle equivalents of the nine most important animal stocks and aggregated with a set of time invariant relative prices . The stock of tree capital is measured as the present discounted value of expected future profits for thirteen different tree crops, using region-specific estimates of expected profits. The subindices are aggregated using region-specific weights estimated by regressing output on the three capital stock sub-indices in the base year 1985.13 Additionally, we control for unexpected shocks in rainfall and temperature to each municipality in each survey year utilizing data described in Wilmott and Matsuura . These quarterly shocks are measured as standardized deviations from 25-year moving averages ending in the year prior to each Census. The data are transformed into categorical variables capturing extremely low, below average, average, above average, and extremely high values relative to the historical municipal average. Weather shocks between -1 and 1 standard deviations are treated as normal weather years and are the reference category, with extremely high and extremely low values occurring at more than ±1.645 standard deviations. The data used are drawn from a nation-wide decennial census and are potentially subject to multiple sources of measurement error. The literature on measurement error and its implications for the IR has grown rapidly in recent years. Of greatest concern are non-classical types of measurement error that are correlated with farm size. Carletto et al. , Carletto et al. , Abay et al. and Dillon et al. examine measurement error in self-reported farm size relative to more accurate approaches to measuring land . They demonstrate clearly that farmers report area with error, that this error varies systematically with farm size, and that whereas small farms tend to overestimate farm size, large farms tend to underestimate their size. The implications for the IR literature are mixed, as Carletto et al. and Abay et al. find that the IR becomes stronger when measurement error in farm size is the sole correction made, but Carletto et al. and Dillon et al. both find that correcting for such measurement error partially mitigates the IR in some of their data but has no statistically significant impact elsewhere. Similarly, several recent papers have explored the implications of non-classical measurement error in output. Desiere and Jolliffe , Gourlay et al. , and Lobell et al. show non-classical measurement error in self-reported output when compared to “crop cuts” as the gold standard measure. Importantly, small farms overreport output more so than larger farms in their data. Conditional on GPS land measurement, the IR disappears in these papers when they utilize the more objective measure of output. Abay et al. explore measurement error in both farm size and output, and concur that in their data the IR disappears when land is measured objectively and then crop cuts are used to correct for measurement error in production. However, they caution that the IR strengthens when land is self-reported and measurement error in output alone is corrected. Lastly, measurement error in the use of inputs such as labor is potentially an issue. Relative to weekly surveys conducted in-person or by phone, end of season surveys of labor usage can contain substantial errors .

The four new fungicides were moderately to highly effective in reducing PRR and P. cinnamomi populations in rhizosphere soil of the avocado seedlings and rootstocks used. Overall, oxathiapiprolin was the most effective among fungicides evaluated. In experiments with Zutano seedlings, the efficacy of oxathiapiprolin at the low rate of 70 g/Ha was 2- to 33-times higher than that of the other fungicides and 2- to 4-times higher than that of mandipropamid, a CAA fungicide. In a study on managing P. capsici on peppers , the difference in effectiveness of oxathiapiprolin at 30 g/Ha as compared to the CAA dimethomorph at 262.5 g/Ha was similar to our study using the same FRAC codes of fungicides. In response to reducing PRR, avocado plants treated with oxathiapiprolin generally developed more shoot and root growth as compared with untreated plants. On the avocado seedlings and rootstocks used, fluopicolide, mandipropamid, and ethaboxam treatments also effectively reduced the incidence of PRR compared with the control. P. cinnamomi propagules in the rhizosphere soil were only significantly reduced on the Zutano seedlings and the Dusaâ rootstock. These latter treatments were often significantly more effective than potassium phosphite or mefenoxam; whereas fluopicolide often performed statistically similar to oxathiapiprolin. Still, the efficacy of potassium phosphite was demonstrated with significant reductions in PRR on the seedlings and rootstocks although its overall performance may have been compromised by the use of three P. cinnamomi isolates with reduced sensitivities to the fungicide in our soil inoculations. These results also could explain why potassium phosphite is still effectively used in managing PRR in California since many growers cultivate avocado trees grafted on the Dusaâ rootstock. Thus, flower buckets wholesale highly effective alternatives to mefenoxam and the phosphonates were identified by us for the management of avocado PRR.

Oxathiapiprolin used at low rates provided similar or better efficacy than the other fungicides. Oxathiapiprolin, fluopicolide, mandipropamid, and ethaboxam previously demonstrated high efficacy against selected foliar and root diseases of vegetable and tree crops caused by Oomycota organisms in greenhouse and field studies. Thus, the four fungicides were highly efficacious in reducing Phytophthora root rot of citrus caused by P. nicotianae and P. citrophthora . Oxathiapiprolin, fluopicolide, and mandipropamid were more effective in managing P. capsici on watermelon than mefenoxam or potassium phosphite . In other studies, oxathiapiprolin was shown to be highly effective in managing diseases of vegetable crops caused by Phytophthora species including P. capsici and P. infestans and controlled black shank of tobacco caused by P. nicotianae . Ethaboxam was shown to be an effective treatment for tomato late blight , as well as Phytophthora blight of pepper . Based on our studies, registration of oxathiapiprolin for use on avocado has been initiated through the Inter-regional Research Project No. 4 , and ethaboxam, fluopicolide, and mandipropamid are proposed for further development on avocado. Additional evaluations will have to be done under field conditions using rootstocks with different growth characteristics and susceptibilities to PRR. The availability of fungicides with new modes of action and options for rotation and mixture programs using previously registered and new fungicides will help reduce the risk of development and spread of resistance in P. cinnamomi populations in California avocado production. Growers currently rely heavily on the use of phosphonate-based fungicides, and as we demonstrated, pathogen populations are shifting towards reduced sensitivity to this fungicide class. Thus, there is an urgent need to register fungicides with new modes of action. In our greenhouse studies, overall treatment efficacy in reducing PRR and soil inoculum levels of the pathogen on the susceptible PS.54 was reduced as compared with the more tolerant Dusa rootstock, indicating additive effects of fungicide use and rootstock selection. In an integrated approach for a durable and effective management of PRR that allows the continued economical production of avocados in P. cinnamomiinfested soils, the use of tolerant rootstocks is critical along with irrigation management and cultural practices such as using mulching and planting in areas with good soil drainage.

There are Phytophthora species that can infect only one, or a few different hosts like Phytophthora infestans de Bary, and then there are species that can infect hundreds or even thousands of different plant species such as P. cinnamomi Rands . P. cinnamomi is of particular interest in California because it causes Phytophthora root rot of avocado, in fact, PRR is the most destructive disease of avocado production worldwide . PRR limits production of avocado by killing feeder roots which reduces fruit yield and can cause tree death . P. cinnamomi impacts other fruit crops such as peach, pineapple, and high bush blueberry, as well as affecting natural stands of eucalyptus, pine, and oak . Areas that have become infested with P. cinnamomi will never completely remove this pathogen from the soil. Current chemical treatments are being challenged by the emergence of isolates that are more virulent and less sensitive to potassium phosphite . The current challenges of PRR treatment of avocado necessitates a better understanding of the molecular and genetic basis of plant-P. cinnamomi interactions. Taking advantage of the wide host range of P. cinnamomi, we developed a detached leaf assay in Nicotiana benthamiana to elucidate the molecular and genetic basis of plant immunity against P. cinnamomi . The hemibiotrophic lifestyle of P. cinnamomi was confirmed in this model system through differential staining and quantitative PCR pathogen DNA quantification. The model plant, N. benthamiana , has been widely used to study the pathogenicity and virulence of similar broad range and root Phytophthora pathogens such as P. capsici , P. palmivora , and P. parasitica . Furthermore, several studies using model plants, crops, and tree crops to study pathogenicity, virulence, and fungicide efficacy of root rot pathogens such as P. sojae, P. capsici, P. parasitica, P. palmivora, P. cinnamomi, and P. ramorum have been performed using detached-leaf assays . Using the tools developed in previous studies and combining them with RNAseq analysis as well as functional assays using this model plant it becomes possible to gain a better understanding of plant defense responses against P. cinnamomi infection.

Previous transcriptomic studies on avocado and model systems provides important information on plant gene expression in response to infection by P. cinnamomi. Avocado defense gene expression has been analyzed three separate times over the last eight years . Mahomed and Van den Berg used the tolerant avocado rootstock Dusa to study the gene expression changes after P. cinnamomi inoculation. By comparing expressed sequence tags and 454 pyrosequencing they were able to identify six defense related genes. The defense genes identified encoded: cytochrome P450-like TBP , thaumatin, PR10 , metallothionein-like protein, MLO transmembrane protein encoding gene, and a gene encoding a universal stress protein . In a follow up study, again on the resistant avocado rootstock Dusaâ , 16 additional defense genes encoding: WRKY transcription factors, phenylalanine ammonia-lyase , beta-glucanase, allene oxide synthase, allene oxide cyclase, oxophytodienoate reductase, 3-ketoacyl CoA thiolase, Fbox proteins, ethylene biosynthesis, isoflavone reductase, glutathione s-transferase, cinnamyl alcohol dehydrogenase, cinnamoyl-CoA reductase, cysteine synthase, quinone reductase, and NPR1 were differentially expressed after P. cinnamomi infection. Reeksting et al. found up-regulated transcripts corresponding to cytochrome P450, a germin-like protein , flower harvest buckets and chitinase genes after P. cinnamomi infection using microarray technology. It has been stated , that an important difference between gene expression in avocado and model systems is that the salicylic acid response is only seen in infected avocado, which is associated with a defense response to biotrophic and hemibiotrophic pathogens. It has been further asserted that P. cinnamomi infection of model plants initiates the jasmonic acid and ethylene pathways associated with necrotrophic pathogens. Although there are differences between expression patterns in avocado and the numerous model plants that have been studied to better understand plant defense to P. cinnamomi, there are also many similarities. Model plants used to better understand plant defense gene response to P. cinnamomi infection include; Zea mays, Arabidopsis thaliana, Lupinus angustifolius, Castanea sativa , Eucalyptus nitens, Lomandra longifolia, and most recently N. benthamiana . The gene expression in susceptible model hosts such as L. angustifolius and N. benthamiana can be compared to tolerant hosts like A. thaliana and L. longifolia to identify differences that may be associated with resistance to P. cinnamomi. Santos et al compared the gene expression between a susceptible and resistant variety of chestnut. They found that genes encoding for proteins involved in pathogen recognition proteins , were significantly upregulated in the resistant variety especially before inoculation. Six out of eight defense related genes including; WRKY31 and LRR-RLK’s were more highly expressed in the uninoculated C. crenata when compared to the uninoculated C. sativa. This increased basal defense to P. cinnamomi may contribute to this variety’s resistance. Gene expression in E. nitens in response to P. cinnamomi infection included up-regulated overrepresented gene ontology terms related to JA and ET signaling . Interestingly, pathogenesis-related gene 9 was down-regulated and represents a cross-species effector target during P. cinnamomi infection. Functional genomics and validation of these defense genes has only been performed in one study in A. thaliana. Eshraghi et al. reported that an auxin Arabidopsis mutant was more susceptible to P. cinnamomi infection than the wild type indicating the role of auxin pathways in P. cinnamomi defenses. The main challenges for the identification of P. cinnamomi resistance genes in avocado are the lack of tools available for functional genomic studies and limitations associated with tree crop biology. Next-generation sequencing has provided some information on the expression of defense-related genes in avocado infected with P. cinnamomi. However, the lack of the genome sequence and absence of functional genomic tools for avocado makes it difficult to determine and confirm their contributions to resistance against P. cinnamomi.

The N. benthamiana model plant provides the opportunity to conduct functional genomic studies to determine the role of defense response genes to P. cinnamomi resistance that is not yet available in the avocado system or other tree hosts. Model plants including A. thaliana , L. angustifolius , and Medicago truncatula have been previously reported as susceptible hosts for this oomycete pathogen and have been used to study P. cinnamomi pathogenesis and plant responses to this pathogen. Although whole genome sequencing was available for these pathosystems, functional assays were not conducted with the exception of one study in Arabidopsis implicating the auxin signaling pathway with defense response against P. cinnamomi . Conducting RNAseq studies in N. benthamiana system at different time points during the infection process will provide a foot-hold into the defense gene expression pattern during P. cinnamomi infection and will allow us to conduct functional studies of selected defense genes using this N. benthamiana–P. cinnamomi pathosystem. Differentially expressed pathways and genes can be then validated by RT-qPCR in N. benthamiana and in avocado inoculated with P. cinnamomi using a detached leaf assay. Functional validation of the most promising genes can be done in N. benthamiana by transient over expression or silencing to determine their contribution to P. cinnamomi resistance. If similar expression patterns are found in avocado it is reasonable to consider this gene a good candidate for marker assisted breeding or biotechnology in avocado. As genomic tools for avocado quickly become more available the methods developed in this system will become more applicable to this fruit tree crop. RNAseq analysis of infected N. benthamiana roots can complement this system by identifying what genes are universally expressed in the plant in response to P. cinnamomi infection and what gene expression is unique to the roots. Functional genomics are lacking in avocado; therefore, the objectives of this study were i) to establish a model system to look at defense gene expression in response to P. cinnamomi infection, ii) validate differentially expressed defense genes using overexpression in the same N. benthamiana model system, and iii) establishing connections to similarly expressed defense genes in avocado in response to P. cinnamomi infection. This information will help to select candidate defense genes in avocado for marker assisted breeding or biotechnology. The average total million reads for the sequenced mock-inoculated N. benthamiana samples were 66, 75, 75, 81, and 70 million for the 6, 12, 24, 36, and 48 hpi time points respectively. The average total reads for the inoculated N. benthamiana samples were 145, 123, 80, 62, and 70 million reads for the 6, 12, 24, 36, and 48 hpi time points respectively. The average percentage of reads mapped for the five-mock inoculated time points was between 86 and 88%.

At the end of the harvest season, when the seasonal farm workers prepare to return home, established workers sell their good hunting dogs for up to $1000 pesos to migrant workers who purchase them using the earnings from the harvest season. In the process of describing the everyday-lived-experience of farm workers, is important to also recognize that the experience of the finqueros themselves is often overlooked, which in turn encourages a shallow understanding of the complexity of the problems faced by migrant workers in coffee plantations. Similar to what Holmes describes in the case of migrant farm workers in US agriculture, the increasingly corporatized market “squeezes growers such that they cannot easily imagine increasing the pay of the pickers or improving the labor camps without bankrupting the farm” . As he continues, “perhaps instead of blaming the growers, it is more appropriate to understand them as human beings doing the best they can in the midst of an unequal and harsh system” . The struggle in coffee plantations is experienced on its own way by the finqueros, who find themselves “squeezed” between the pressure of the market, increasing indebtedness and the social stigma that accompanies large plantations in this region. The finqueros I interviewed for this work were generally concerned about the living conditions of their workers and expressed future plans to improve mostly infrastructure, but find themselves with their hands tied in the face of low prices and few economic benefits from the premiums offered by the specialty market. On the one hand finqueros most catch up with current trends that include roasting their own coffee, which requires special infrastructure, special training, as well as high investments. On the other hand, growers have also had to incorporate the touristic aspect of their plantations, create and recreate the colonial stories that forged these places, build attractive bungalows and spas, black plastic plant pots wholesale and sell coffee as a whole new “experience of the senses”, that includes biodiversity conservation at its center and the recasting of colonial narratives .

As one of them puts it: “el turismo hace maravillas” . In addition, in order to increase economic gain, finqueros have also started to diversify their income, not only through tourism, but also through the production of ornamentals, cardamom, timber, and medicinal plants, which marketable value increases when being planted along with coffee. Low and unstable coffee prices, in combination to a changing climate and disease outbreaks, add to the struggle of coffee growers, which blends with the problem of low productivity of their shade-grown coffee plantations, and labor shortages for this region7 , a problem that is not new to the region . To add to this problematic, Renard points out: “ The liberalization of the international coffee market combined with a sharply reduced state intervention engendered the control over coffee production by a few transnational companies and the collapse of the economy of small producers. Combined with natural disasters whose effects were not addressed by the neoliberal state, this situation caused the region to be bypassed by Guatemalan labor that now prefers direct migration to the United States” . Moreover, in the past decade, finqueros in Soconusco and Central America were also challenged by two important coffee leaf rust disease outbreaks caused by the fungus Hemileia vastatrix, that practically swept entire coffee plantations in the region in 2008 and 2013 . This disease is highly associated with climate change , another important environmental challenge that is projected to increase climatic variability and the intensity of rain for this region . At the center of the imaginary is the shade-grown coffee farm, which is offered to the world as a steward of the land, a guardian of endangered species, a place for retreat within lush gardens overlooking a seemingly natural, remote land. However, within the wrinkles and creases of this portrait lies the experience of farm workers laboring in the fields, the struggles, the joys, and the stories that give meaning to this place.

Considering that various visions, knowledge, and experiences converge within the coffee plantation, we can begin to understand it as a co-produced space, one that is constructed through the ecological views and social relations of diverse actors that produce this space : the market and the consumers, the workers and their everyday labor experiences, the owners with their own struggles and desires, and dominant conservation narratives. In some ways, the convergence of ecological knowledges in the coffee plantation, the alternative market boom, and the conservation narrative sold in “First World” cafeterias, has created a particular coffee tropical imaginary. In this sense, coffee produced on shaded and biodiverse plantations is often targeted toward a specific environmentally conscious, upper class consumer that engages with these narratives by both directly buying the coffee as commodity, and through ecotourist vacations to coffee plantations. Shaded plantation coffee is also presented as a luxurious commodity associated with a type of tropical imaginary that, in actuality, is produced at the expense of farm workers’ living and working conditions. This work questions the practices and narratives surrounding biodiversity conservation in the context of farm workers’ lives. Farmworkers in coffee plantations are a highly vulnerable sector in the coffee production chain. In these labor-intensive systems, they not only suffer unfair living and working conditions, but also face fears and anxieties posed by conservation practices and discourses: the need to harvest coffee in the dense vegetation or abundant leaf litter, and the strict regulation around the use of resources to supplement their daily diets. Multiple imaginaries have shape this landscape dominated by coffee. On the one hand, neoliberal market trends in coffee production– which have brought the multiple certification schemes we can find in the supermarket– have imposed dogmatic regimes around the production of coffee , which– as I have shown– are at odds with people’s needs and desires. On the other hand, scientists have often promoted an imaginary around shade-grown coffee production, which reminds us of a natural or seemingly natural portrait, in which humans are nonexistent . These imaginaries, supported by an exclusionary narrative of biodiversity conservation, obscure the lived experience of farm workers. I also bring attention to an important problem in organic production, which is the fact that it does not question social conditions, particularly of farm workers, despite presenting itself as a label with social responsibility. Issues such as poor wages, structural violence, social segregation, and racism are aspects of the daily lives of farm workers in systems that depend heavily on migrant labor . However, there is a strong emphasis on ecological sustainability goals, that ignore such issues. The social implications of these labels and discourses about conservation in a labor-intensive system are striking. Therefore, in the practice of questioning our current food regime, we must reflect and recognize how narratives of conservation might reinforce farm workers’ marginalization. A change of paradigm in the conservation narrative in shaded coffee plantations should acknowledge workers’ experiences, but not only the ways in which farm workers experience injustices in the plantation, such as prohibitions, unequal pay, forced labor, bodily pain, and unfair living conditions; also, the potential subtle and creative ways of contesting them, which challenges a potential passive and subjugated vision that their experiences might provoke on the reader. For example, disregarding hunting prohibitions, using the work in coffee plantations to reproduce the peasant living back at home, appropriating land in abandoned areas of the plantation, and gossiping and character assassination of powerful figures within the hierarchy of the plantation , all as an act of autonomy or “everyday resistance”. Similarly, I acknowledge the fact that plantation owners also find themselves squeezed in various narratives: the push to be more ecologically sustainable, the unforgiving reputation that many of them receive by the media and the adjacent ejidos, black plastic plant pots bulk the push to be more productive in a competitive market while being socially just, all within a reality of low coffee prices, and increasing indebtedness to international buyers and powerful corporations, such as Nestle and Starbucks.

In some way, finqueros benefit from the conservation narratives and the imaginary of shade grown coffee plantations, as they are able to accommodate their coffee with much more identity and value in the market. Finally, this research invites all of us as scientists, tourists, and coffee consumers to rethink our political actions as we construct the spaces that we visit, study, and imagine. In a time of increasing violence towards immigrants, and a food regime increasingly dominated by corporations, it is pertinent to ask how our actions change and perpetuate current neoliberal models, that are ultimately detrimental to the lives of people that live with and from coffee. Coffee is an important agricultural system for Latin America, supporting millions of farmers and national economies. A large portion of coffee in Latin America is produced under the shade of forests, making this habitat important for the conservation of biodiversity and ecosystem functions, as well as the sustenance of human livelihoods. Through the analysis of species interactions and human lived-experiences I provide a glimpse to the social and ecological complexities of organic shade-grown coffee plantations. Shaded coffee plantations are complex socioecological systems constructed through our scientific understandings of ecological interactions, insects and other organisms, as well as by the experience of people making a living in these spaces. My work contributes to our understanding of complexity through the lens of humans and non-humans, and paints a portrait of shade grown coffee that shows Los claroscuros del café, or the disambiguation of this space. On the one hand, my research contributes to our understanding of the mechanisms that maintain species diversity and complex interactions in complex agroecosystems. From an agroecological perspective, resource heterogeneity, and the availability of a diverse suit of resources, including food, nesting and connectivity resources can promote species richness and biological pest control in coffee systems. My research highlights the importance of conserving specific resources for insects in the face of increasing agricultural simplification. From a political ecology perspective, my research brings attention to an overlooked aspect of shadedcoffee systems, which is the lived experience of farm workers, and indirectlyinvites all of us to rethink our political actions as we construct the spaces that we study. Highly parallel genotyping has become an important component of genomics. Hybridization of genomic DNA and RNA to microarrays has been used in the past for detection of polymorphisms between genotypes. However, the previously available arrays for complex genomes only provided limited transcriptome coverage. We developed an array designed to maximize transcriptome coverage while maintaining the possibility of performing other analyses. Our custom designed Lettuce GeneChipW combined the benefits of overlapping probes across unigenes, similar to that demonstrated by Gresham et al. for yeast, with the use of anti-genomic probes to maximize the possible coverage of unigenes while maintaining the sensitivity to detect polymorphisms and retaining appropriate controls to normalize and correct for background noise. The tiling path design allows for multiple assessments of hybridization differences between lines for single positions rather than single assessments of a few positions as obtained with most expression arrays. We developed custom scripts for analysis of our hybridization data taking into account the multiple probes covering a single position as well as filtering out poorly performing probes. We used recent advances in high throughput sequencing technology to validate our SPP calls as well as filter out potentially unreliable data. Genomic DNA and cDNA are two options for hybridization to an array for SFP detection. The decision of which to use becomes more difficult as genome size and complexity increases. DNA as well as cDNA are both viable targets for species with smaller genomes such as Arabidopsis and rice. However, with larger and more complex genomes such as barley, cDNA was indicated as a more reliable option for hybridization even with the added difficulty of subtracting out expression effects. The genome of lettuce is nearly 17x larger than Arabidopsis although it is half the size of barley. Given the difficulty of accounting for spatiotemporal expression effects as seen in cDNA, we focused on developing methods to use genomic DNA. Rostokset al.suggested that genomic DNA may be a feasible target in larger genomes with added replication. With the redundancy of the overlapping probes in the lettuce array, the need for additional replication was reduced because they provide technical replicates within a chip.

Extensive studies of community assembly of ants in the coffee agroecosystem reveal that both environmental filtering, which is frequently associated with nesting opportunities , and competitive interactions are likely involved . Here we divide that literature into two general groupings, ants that generally nest in the ground or leaf litter, broadly construed, versus ants that nest in hollow cavities, generally referred to as twig-nesting ants. The first, we suggest, are structured largely through competition for feeding resources, whereas the second are structured more through competition for nesting sites.The general spatial patterns seen with ground-foraging ants are frequently thought to result from interspecific competition . Part of the evident spatial structure is the existence of mosaics in which patches of dominant species are arranged in space something like a jigsaw puzzle. Ground-foraging ants on coffee farms seem also to form this mosaic spatial pattern; various species form patches that are relatively discrete, with each species occupying its own space and the patches fitting together almost as if they were pieces in a jigsaw puzzle . Studies in coffee farms suggest that much of the spatial pattern of ground-foraging ants is indeed a consequence of the underlying structure of competitive interactions among the various species , although that structure is not simple.For both arboreal ants that nest in hollow trees or shrub twigs and leaf litter ants that inhabit hollow twigs on the ground, the size, number, or diversity of available twigs may be an important determinant of community structure. For arboreal ants in coffee agroforests, hollow coffee twigs and shade-tree twigs and branches comprise the vast majority of available nest sites, and there can be considerable variation in the size of twigs available. However, in the coffee plants themselves, most ants prefer to nest in similar-sized twigs . Although one larger ant species, Procryptocerus hylaeus, occupied twigs with larger cavities in the field and selected larger twigs in choice experiments in the lab, 30 planter pot nine other species examined showed no difference in the mean nest size occupied .

Nest availability also strongly varies, and competition for nesting resources may be an extremely important determinant of community structure and contribute to community assembly processes in tropical communities. Work in coffee farms has enabled learning the importance of diversity, quality, and size of nesting resources for community assembly. Ants compete for nesting resources, and among indications of nest limitation in ants are the occupation of a large fraction of available resources, takeovers of nests by different colonies or species, and occupation of artificial nests . Coffee agroforests that differ in shade structure,and therefore in the overall availability of nest sites, have been used to demonstrate the importance of nest-site limitation for ants, and the fact that nest-site limitation can contribute to a loss of ant diversity . In a comparison of two different coffee farms varying in the amount of shade, nest-site limitation was stronger in farms with less shade. In addition, increasing the number of artificial nests in high-shade coffee farms resulted in a large increase in the number of species colonizing twig nests, but there were less dramatic increases in richness in low-shade sites . Thus nest limitation, but also other processes must be important drivers of community assembly in large, intensively managed farms. In coffee agroforests in Colombia, nest-site limitation is important for twignesting ants both on coffee plants and in the leaf litter. With a similar technique, Armbrecht et al. added artificial nests to coffee plants and added artificial nests and leaf litter in forests and in three coffee systems varying in shade management to examine the bottom-up influences of resources on ant assembly. Both litter addition and twig addition increased the number of ant colonies, indicating that ant colonies in these habitats are litter- and nest-limited. The numbers of ant species colonizing resources did not increase with litter or twig addition but did increase with increasing shade in coffee farms, a similar result to that found in Mexico . Nest diversity may also be important in determining the numbers of species that can colonize and survive in tropical environments. In Colombia, Armbrecht et al. tested whether the diversity of nesting resources affected colonization by litter-dwelling ants.

They collected branches of eight species of shade trees and drilled holes in the branches so that they would resemble natural hollow twigs found in the leaf litter. They then placed the nests in bags and added the bags to the leaf litter on the ground in either single-species bags, containing eight twigs of the same tree species, or mixed bags, containing one twig of each of eight tree species. They found that the mixed bags were colonized by a significantly greater diversity of ants but not for the reasons expected. Whereas it was expected that different species of ants would select different species of twigs, leading to an increase in ant diversity in mixed bags, they instead found that most ant species preferred the mixed bags, but not due to strong tree-species and ant-species associations. Thus, diversity in a nesting resource greatly influenced ant assembly and led to a more diverse ant community. Ecological interactions with other species, such as dominant ants or parasites, may also contribute to the structure and maintenance of ant communities. The presence of aggressive, dominant ants may influence the foraging by arboreal ants and may also limit their abilities to colonize new areas as well as limit their access to food resources and perhaps survival once they are established. But little experimental work has documented the importance of arrival and survival processes for ant communities . Two interesting studies in coffee farms have documented the importance of aggression from canopy-dominant ants on twig-nesting ants that belong to a different nesting guild. A. sericeasur ants are aggressive toward many types of arthropods, including even birds. In a manipulative field experiment, Philpott added artificial nests on coffee plants with A. sericeasur foragers and on coffee plants without A. sericeasur foragers to assess their impact on nest colonization. Fewer nests were colonized by twig-nesting ant species when A. sericeasur were present, and six out of ten common species occupied significantly more artificial nests placed on plants without A. sericeasur. Nest colonization increased with tree density , indicating that both abiotic and biotic factors are contributing to assembly processes for this community.

In a clever experiment to test the influences of the A. sericeasur–C. viridis or ant-scale mutualism on foraging by A. sericeasur and other arboreally foraging ant species, MacDonald et al. sprayed scale insect populations near clusters of A. sericeasur nests with an aqueous solution of L. lecanii, a fungal parasite of the scale insects. TheL. lecanii killed significant numbers of scales and resulted in increases in the foraging of other ant species proportional to the reduction in the numbers of A. sericeasur foraging on coffee plants. Thus A. sericeasur likely affects not only arrival but also survival of the twig-nesting ant colonies in coffee farms. As an aside, plastic growers pots the same sorts of reductions in foraging by A. sericeasur are also experienced frequently when they are under attack by Pseudacteon spp. phorid flies, resulting in similar increases in resource access for twig-nesting ant species . Such manipulative experiments have rarely been conducted in natural habitats, highlighting the role of coffee farms as model systems for ecological tests. Coffee farms have also provided a natural laboratory for simultaneously testing multiple hypotheses for community assembly. Livingston & Philpott used twig-nesting ants to investigate drivers of community assembly, including nest-site preferences; environmental filters, such as nest-site abundance and disturbance by A. sericeasur; influences of competition among ant species; and stochastic dispersal. They examined co-occurrence patterns of 25 twig-nesting ant species and used a “core/satellite” approach to address dispersal heterogeneity among species in the community . Species were divided into four groups: core species that are common at both local and regional scales, regional dominants that are found globally and dominant locally, local dominants that are dominant locally but not well distributed globally, and satellite species that are neither dominant locally nor well distributed. According to theory, competition among core species should result in overdispersed co-occurrence patterns , whereas dispersal effects should result in random or aggregated co-occurrence for satellite species. Several patterns emerged from the field analysis. First, >60% of twigs were occupied, demonstrating strong nest-site limitation. Second, most ant species inhabited similar-sized twigs, all species examined had proportionally similar responses to gradients in nest-site abundance, and A. sericeasur presence had little influence on richness or composition of ants occupying coffee twigs. Thus, Livingston & Philpott concluded that species sorting through environmental filters plays a minor role. Third, all ant species showed random patterns of co-occurrence with respect to each other in the absence of the “core” species, Pseudomyrmex simplex. But in the presence of P. simplex, regional dominants, local dominants, and satellite species showed aggregated patterns of co-occurrence with respect to one another. Thus, P. simplex likely plays an important role in “assembling” the community by providing a core meta population into which the other species fall.

Fourth, there was evidence for priority effects, as two ant species of equal competitive rank rarely co-occurred. Taken together, these data provide support for a competitive meta-community structure and suggest that competition for nest sites should be the dominant species interaction in this community. In a follow up paper, Livingston et al. used an expanded data set, coupled with data on dispersing alates , to examine evidence for species sorting and mass effects . They used data on twig-nesting ants from natural twig nests in five microhabitat types in a shaded coffee agroecosystem and coupled this with data on artificial nest occupation and numbers of alates caught in light traps. They then used community similarity and a variance decomposition to partition community variance into spatial and environmental components. Twig-nesting ant communities were distinct in each of the five microhabitats, and dissimilarity among communities was largely driven by changes in relative abundance of dominant and subdominant species but also by extensive turnover in the rare species. Space and environment together predicted 24.5% of the variation in the ant community, and space and environment explained unique fractions of the variance, indicating that both species sorting and mass effects are likely important drivers in this community. Alate abundancefor a species was correlated with colony abundance of species, indicating that microhabitats are dominated by internal dispersal. Finally, ant richness in artificial nests was higher than that in natural nests in coffee; however, natural nests had higher richness than artificial nests in shade trees and in the forest. Thus, abundances of the dominant and subdominant species are predominant in community dynamics, and dispersal of rare species from the canopy or adjacent forest patches may support mass effects into coffee microhabitats. To summarize, evidence to date for this twig-nesting ant community suggests that environmental filtering at the level of the nest may not occur but that some differences in habitat may impact ant assembly. Furthermore, dispersal and competition appear to be highly important in this community.Azteca sericeasur nests in trees and is common in the Mesoamerican tropics, where it is frequently encountered on casual walks in the forest. However, discerning any spatial pattern of its colonies in a tropical forest is inevitably obstructed by the heterogeneity of the habitat. In a 45-ha plot regular surveys revealed that Azteca colonies were distributed neither randomly nor uniformly within the plantation. Rather, they were strongly clustered . Examining a variety of environmental factors, such as slope, identity of nesting tree, and size of nesting tree, showed that nothing external to the ant population was correlated with the clusters, suggesting that the underlying biology of the ant was potentially the source of a self-organized pattern. The basic biology of the ant is not unusual for a species that has multiple queens and may be quite general for species that acquire most of their energy from hemipterans . After a queen establishes a colony in a tree, the colony may grow to the point that new nests are established in neighboring trees, evidently one part of the mechanism whereby patchiness is generated. However, unabated new nest formation would obviously result in a continuous expansion of colonies, which means that some force must limit this expansion. Turing’s concept of diffusive instability is a useful metaphor , with the tendency of the ants to disperse to neighboring trees equivalent to the “activator” of the system. However, there must also be some “suppressor,” otherwise the ants would simply disperse over the whole farm.

Although highly mobile, lechugueros represent a much more stable labor force than, for example, migrant strawberry pickers. Santa Barbara County’s fourth value crop is cauliflower. It engaged 8,920 acres of the Santa Maria Valley’s prime farmland and generated $29.5 million in 1992 . Like other crops described above, cauliflower boomed from under 1,500 acres in the late 1970s to nearly 9,000 today . Crop prolificacy also has risen from under 9,000 pounds per acre to 15,000 in the same period of time . As the close relative to broccoli that it is, cauliflower presents similar production and employment characteristics. It is, for example, farmed nearly year round and, as a result, offers a relatively steady source of employment to a number of local farm workers. Demanding 96.5 man-hours per acre to produce , Santa Maria’s current cauliflower acreage consumes 860,000 man-hours. Two-thirds of the labor requirement is used to harvest and field pack, and the remainder to plant and cultivate. We estimate that some 800 workers are employed regularly but intermittently by local cauliflower farms to complete these tasks. Harvest crews surveyed in 1993 revealed that all employees, like broccoli crews, are local permanent residents. Weeding and thinning crews, moreover, revealed that they are, in great measure, made up by the same local workers who execute similar tasks in the broccoli fields. Wine grapes are Santa Barbara County’s sixth value crop. Vineyards issued $28 million in 1992 and occupied 9,532 acres . Prior to 1970 there were no commercial vineyards in Santa Barbara but soon afterwards the industry took-off owing to growing national demand for wine, blueberry in container especially for the premium varieties Santa Barbara is capable of producing . In 1975 some 7,000 acres had been appropriated by the crop and by the early 1980s growth had leveled to the current acreage .

Although many of Santa Barbara’s vineyards are located in the neighboring Santa Ynes Valley, much of the new growth has occupied the hills and slopes that surround the Santa Maria Valley. Moreover, much of the labor employed by the county’s vineyards finds temporary or permanent lodging in the Santa Maria area. Wine grapes require approximately 110 man-hours per acre to cultivate and harvest . Much of the vineyard work is spread throughout the year and, consequently,requires only small crews to, among other things, prune the vines, till the soil, inspect and repair trellises and drip irrigation lines, fertilize and spray, and complete pre-harvest leaf removal. Harvest, in contrast, claims one-half of the annual labor requirement during a brief and intense moment in the early fall. Because Santa Barbara wine grapes are used to craft premium wines, the fruit must be picked in its prime, that is, during a short, fleeting window of opportunity when a large number of workers must labor in a frenzy to gather the grapes and transport them to the wineries for processing. Although mechanical means are currently available to harvest wine grapes and, in fact, most Santa Barbara vineyards have been designed and trellised with this in mind, growers continue to hand-harvest their crops in order to ensure the highest possible quality product. Santa Barbara vineyard acreage, according to available man-hour/acre computations, requires some one million man-hours to cultivate and harvest. We estimate that three hundred workers, employed intermittently during the course of the year, supply the labor needed to complete all the production tasks with the exception of harvest. All non-harvest employees are local resident workers, and many combine intermittent employment in the vineyards with employment in other local crops. Harvest crews, in contrast, are made up by both local and migrant workers.

Our 1993 survey of grape harvest crews, in effect, revealed a prevalence of transient migrants with a smattering of local residents, including many who had participated in other valley crops, especially strawberries, during the course of the summer. With just 2,724 acres, celery yielded an impressive $16.9 million in 1992, making it the county’s seventh value crop . Celery acreage and value are both down relative to 1989 production when 3,478 acres yielded $23.6 million. Nonetheless, it represents another vegetable crop with a healthy consumer demand, especially that which is designed to supply specialty markets. Most Santa Maria celery is, in effect, grown for premium markets and, as a result, is pampered during cultivation and then hand harvested. Celery is essentially a cool-temperature crop which thrives in the temperate winters of the California coast. In the Santa Maria Valley, plantings are established during the late summer and early autumn to be harvested from November to July when the long summer days and increased temperatures impel the plant to bolt. The cultivation of celery actually begins in nurseries where seedlings are started and prepared for transplantation to the fields. Growers stagger transplanting activities in a way that will assure an extended but steady harvest. Although mechanical planters are normally used, work crews are also needed to feed and assist the machine, and to correct frequent planter errors. When the ground is too wet, owing to rain or irrigation, the use of the mechanical planter must be forgone altogether. Weeding is intense and harvest constitutes a major enterprise. Depending on whether mechanical planters are used or not, celery requires from 240 to 320 man-hours per acre to produce, much of it, about 150, during the harvest alone . The celery harvest is arduous, back-breaking and, considering the presence of a large number of workers swinging razor sharp instruments in a fairly restricted space, it is deemed to be quite dangerous indeed. Harvest crews, as a result, are made up almost exclusively of young men. Based on available man-hour/acre computations, Santa Maria celery acreage requires some 800,000 man-hours to produce. Field observations, moreover, allow us to estimate that harvest crews employ about 400 workers who enjoy a seven-to-eight-month season of reliable but intermittent employment.

Transplanting and farming crews employ about 175 workers on a fairly regular schedule during at least six months of the year, while nursery work employs some 50 workers year-round. The celery industry, like lettuce, has established specialized harvest crews that move about California coastal celery-growing sites . In contrast with the lechugueros who tend to live in the United States-Mexico border area and enjoy a relatively stable relationship with their employers, celery cutters are typically migrants from the interior of Mexico and suffer high attrition rates. The celery harvest offers young men an excellent opportunity to make good money, but few workers remain in its employment for more than a few years. Nursery employees and celery cultivators , on the other hand, are mostly derived from the local, settled farm-working population and enjoy stable employment. The six fruit and vegetable crops described above create a 15 million man-hour labor demand in the Santa Maria Valley. However, in order to correctly estimate the valley’s entire fruit and vegetable labor demand it is necessary to make two additional adjustments. First, a myriad of other labor-intensive vegetable crops which occupied 11,230 valley acres and generated $41 million in 1992, augment the valley’s labor demand by at least 1.5 million man-hours. Second, because one-fifth of the Santa Maria Valley belongs to neighboring San Luis Obispo County and we have thus far based our estimates on crop data from Santa Barbara County alone, it is necessary to augment our first estimate by twenty percent. With these two adjustments, the valley’s fruit and vegetable labor demand ascends to nearly 20 million man-hours. If the aforementioned labor demand were to be evenly distributed throughout the year, plastic planters bulk it would create approximately 9,500 full-time jobs. In actuality, because farm employment is not uniformly distributed, Santa Maria’s fruit and vegetable farms employ as many as 23,000 different workers during the course of the year. Controlled field observations and work crew interviews conducted in 1993 suggest that in the Santa Maria Valley: Only ten percent of all farm employees enjoy full-time, year-round employment; twenty percent experience regular but intermittent employment during eight to ten months of the year; forty-five percent attain continuous employment during an extended season of four to six months and, hence, encounter long periods of unemployment; and twenty-five percent are employed only during a short, intense work season of two months or less. Finally, also based on controlled field observations and work crew interviews, we conclude that forty-three percent of Santa Maria’s 23,000 strong fruit and vegetable work force are immigrants who have established themselves permanently in the valley with their families.

The remaining fifty-seven percent are migrants who maintain a home base away from Santa Maria in either the border area or in the interior of Mexico. It is important to note that the number and mix of immigrant and migrant farm workers in the Santa Maria Valley has been in constant flux ever since we initiated our observations there several years ago. This is, in part, the logical outcome of an agricultural economy undergoing rapid, profound change. Two other conflicting forces, however, have also exerted considerable influence over this affair in recent times: On one hand, IRCA’s special provisions for farm workers which, to be sure, invited many former migrants and their dependents to settle down permanently in the valley, have contributed to increase the count of both authorized and unauthorized immigrants, and, on the other, the increasing prominence and rapid proliferation of farm labor contractors who, by preferring to hire new sojourners over established immigrants, stimulate migratory practices while displacing immigrants from their jobs. Nevertheless, in light of 1993 observations, the pulse of the valley is for both immigration and migration to continue growing unabated, probably at a rate which exceeds the creation of new farm jobs. Regarding the April 1 date when the Census Bureau undertakes its decennial count of population, it is important to note that although most immigrants are in the valley at that time, only one-half or less of the migrants are actually there. By early April the strawberry and lettuce harvest is just beginning to build-up steam but is not yet in full swing. Moreover, having just arrived, most migrants are still in the process of making their living arrangements for the season, creating with their great numbers havoc in the local housing situation and probably producing the worst possible conditions for the completion of a sound and accurate population count. Finally, in April the wine grape harvest is still six months away and, as a result, most of the migrant workers who participate in it will be missed as well. According to estimates made in the previous section, some 23,000 farm workers become involved in the valley’s agricultural endeavors during the course of the year. A little over one half of them are migrants who remain in the valley only as long as employment is available, some for just a few weeks, others for as long as eight to ten consecutive months. The other half, more than 10,000, have established themselves permanently in the valley with their families, accounting for as many as one-third of the valley’s inhabitants. The immigrant and migrant farm-working population of Santa Maria, moreover, continues to grow owing to: the farm employment opportunities the valley continues to offer; the dynamics of migration itself as settled migrants draw family and friends from their home communities in Mexico; and ongoing IRCA reverberations. In view of prevailing conditions and observable behaviors, there is no reason to assume that the flow will cease or diminish any time soon despite the fact that the valley already suffers a considerable labor oversupply. Farm workers in the Santa Maria Valley are not an homogeneous lot. The stereotypical view that once served to describe the California farm worker as a nomadic, young, single male campesino from Mexico is of little value today. Among the valley’s numerous farm workers are young and old, male and female , single and married. Some, as we have seen, are settled while others move about. They are, in effect, a broad array of different people displaying diverse and distinct behaviors. Farm workers continue to come from traditional sending communities located primarily in the Mexican central states of, for example, Guanajuato, Jalisco, Michoacan and Zacatecas, but also from new sending communities located in the southern states of, for example, Oaxaca and Guerrero; and some are from as far south as Central America, especially from Guatemala.

The low-ranking, newly important species found in seasonally dry forests were subject to human interest and manipulation, either intentional or inadvertent, routed into cultivation and eventually domesticated . Because they were sparsely distributed over the landscape, hence relatively unattractive to human foragers, there arose an immediate advantage for those who manipulated through burning or harvested species from these habitats so as to increase their density and yield of useful energy or materials. Piperno and Pearsall cite three rationales for using the diet breadth model in this analysis : the archaeological evidence shows that early hunter-gatherer/horticultural residents of the neotropics had an expandingdiet breadth followed by increasing subsistence commitment to low-ranked species; the prehistoric changes of concern are evident enough that short-term precision in the use of the model isn’t necessary ; and finally evidence from ethnographic tests shows that this model and an energy currency are commonly successful in predicting the economic response of foragers to changing environmental circumstances. They conclude, “[b]ehavioral ecology seems to us to be the most appropriate way to explain the transition from human foraging to food production” . Many of the dozen or so early HBE papers on domestication and agricultural origins are fairly general and conjectural. They ask, without too much attention to specific cases or the empirical record of prehistoric findings on this topic, how might the ideas of HBE be used to address the question of agricultural origins? By and large, their authors are ethnographers whose experience is with extant hunter-gatherer societies. And, growing berries in containers they generally have been written by people who already placed themselves within the research tradition of HBE. By contrast, most of the papers in this volume are based on empirical case studies, and they are written largely by archaeologists.

Most are authored by individuals for whom behavioral ecology is a new analytic tool. We do not claim that the HBE research tradition is a complete replacement for the other approaches that we have identified and briefly described. We view it rather as a sometimes complementary and sometimes competing form of explanation. It is complementary in two respects: HBE takes up issues rarely or never addressed in these approaches; search and pursuit trade-offs in the harvest of low-ranking resource species; risk-sensitive adaptive tactics; and, it frames these issues in quite a different manner than other, sometimes older, anthropological and archaeological research traditions by focusing on the costs and benefits associated with individual-level subsistence decisions in localized ecological settings. This framing difference is determined largely by the analytical effort of modeling and hypothesis testing within an explicitly selectionist, neo-Darwinian theoretical framework . In both respects, HBE provides tools that complement or make other traditions more complete. At the very least, HBE provides a theoretically well grounded set of tools to begin exploring the transition to agriculture in a variety of environmental and social contexts. For instance, although Hayden presents his competitive feasting model as a sufficient social explanation for the origins of agriculture, in effect as an alternative to models drawing on materialist or ecological explanations, we would prefer a more cooperative form of analytic engagement. We might assume that social stratification and competitive feasting increase the demand for resources and then ask how this source of ecological change would be represented in terms of foraging models—those extant, adapted, or developed specifically for this purpose—and with what consequences for predictions about subsistence choices and the co-evolution of humans and their resources. Taking this a step further, HBE might help us to identify the socio-ecological circumstances and evolutionary processes that combine to generate a competitive social hierarchy like that expressed in feasting .

A signal strength of HBE is its ability to carry into hypothesis generation a wide variety of postulated sources of causation—global climate change to the aggrandizement of dominant individuals. Nonetheless, to the extent that HBE is successful in addressing the question of agricultural origins, it will raise doubts about or contradict elements of other research traditions. In the process it will help us sort out, appraise and discard faulty elements of these approaches. Thus, for reasons of parsimony as well as theory, those working in the HBE tradition are skeptical of the adequacy of explanations couched at the level of global prime movers such as climate change. Likewise we doubt the efficacy of explanations made in terms of universal, directional pressures,such as Childe’s postulated trend of increasing energy capture or ecosystem approaches premised on cybernetic properties such as homeostasis .Behavioral ecology begins with an optimization premise. As a result of natural and cultural evolutionary processes, behavior will tend toward constrained optimization . This assumption makes operational the long-standing view of anthropologists that hunter-gatherers tend to be skilled and effective in the food quest . Efficiency, say in capturing food energy, is important even if food is not in short supply because it affords hunter gatherers the time and resources to engage fully in other essential or fitness-enhancing activities . We state this premise as constrained optimization because we do not expect behavior to be fully optimal. Temporal lags in adaptation and compromises among conflicting adaptive goals impede this outcome. Optimization likewise must be determined within the cognitive capacities, beliefs and goals of the organism under study. We adopt the assumption of constrained optimization rather than “satisficing” because the latter—while it may lead to superficially similar predictions—is an empirical concept and is therefore not able to generate theoretically robust predictions . Constrained optimization is an analytically powerful starting point that does not entail the belief that behavior is routinely optimal, only that there be a tendency towards optimal forms of behavior.

Behavioral ecology likewise is grounded in the observation, now well confirmed by non-human as well as anthropological studies, that some fundamental economic concepts transcend their scholarly origins in microeconomic attempts to explain the functioning of market-oriented economies. They are useful for studying adaptive decision making whether the questions concern the behavior of capitalists and workers, or the subsistence choices of hunter-gatherers, horticulturalists, and agriculturalists, not to say juncos and bats . At a minimum this list would include marginal valuation, opportunity costs, discounting, and risk sensitivity. marginal value. For most tasks we pursue and things we consume, immediate value changes with quantity, be it duration of the activity or the amount of a good obtained or ingested. The first breakfast sausage is more satisfying than the sixth or seventh; an hour-long bath is a delight, but four hours in the tub makes even insipid alternatives attractive. This would be trivial except for the additional observation that the decision to suspend consuming something like sausage or doing something like taking a bath is based on its marginal rather than initial, average or total value. Because of marginal valuation we move from doing one thing to another even though the intrinsic qualities of the options themselves may be unchanging. The formulation of marginal analysis was fundamental to microeconomics , and the careful reader will find marginal trade-offs in each of the foraging models we discuss below. opportunity costs. The idea of opportunity costs is closely related: the decision to switch from one behavior—a kind of consumption; a work activity—to another depends not only on its marginal value, but on the return to be gained from the available alternatives. Thus, one ceases to consume sausage when it becomes more attractive to sip orange juice; one stops bathing when preparing a ceremony is more compelling. More to the point of our subject, blueberry containers one ceases to forage for mussels when the opportunity and benefits of doing something else take precedence. In each case we assess the current activity, be it consumption or purchase against what we might be doing instead. In technical terms, the opportunity cost of an activity refers to the value of the opportunity that is foregone or displaced by continuing it. For instance, the diet breadth model sets the decision to pursue a particular resource against the opportunity cost of ignoring it in favor of searching for a more profitable resource to pursue. Much of microeconomics is a logical and mathematical elaboration on the workings of marginal valuation and opportunity costs, as they are manifested in the environment of a market economy. Using these ideas, economists ask how a wage earner’s consumption patterns change in response to an increase in her income.

By contrast, the behavioral ecologist analyzes how these two concepts play out as an organism interacts with a natural environment of physical processes and other organisms in the roles of predators, competitors, food resources, potential mates, and offspring. She asks, how might the resource choices of a forager shift as a consequence of a decline in the density of a highly valued resource, or an improvement in the technology used to harvest a particular species? The most basic claim of the papers in this volume is that these same ideas can be adapted to an understanding of decisions faced by humans during the evolutionary transition between foraging and agriculture. discounting. Discounting refers to the situation in which we assign a future reward less value than if it were available immediately and with certainty. For instance, we would pay less at planting time for a corn crop which might after all fail, than for that same crop at harvest time when the yield is certain. We discount in this manner when the cost of an activity such as planting occurs immediately but the reward, the harvest, is delayed and, perhaps because of that delay, uncertain. Delay alone can be important because the opportunity to benefit, even from a completely assured harvest in the most extreme case might diminish or pass, were the cultivator to die in the meantime. Delay also offers opportunities for hailstorms, locust plagues and other unforeseen events to reduce the value of the reward itself. For both reasons, effective behavior will hedge, finding it economical to discount delayed rewards. Use of this concept is fairly recent in behavioral ecology theory . Because the shift from hunting and gathering to agriculture represents a shift from immediate- to delayed reward activities this basic concept likely will be quite important in economic analyses of the transition from foraging to farming. risk-sensitive behavior. Basic behavioral ecology models assume that all environmental variables are constants and that a forager pursuing an optimal set of resources gets the expected reward at all times. By contrast, risk-sensitive models aim to be more realistic by introducing a stochastic element to the relevant environmental variables. All hunters recognize the large role of chance in the discovery and successful capture of game. In a risk-sensitive model the acquisition rate experienced by the forager is expressed by a statistical distribution; outcomes can be assigned probabilities but the actual rate at any time is unpredictable. Therefore, the optimization problem must take into account both the long-term average and the inevitable periods of shortfall. Risk-sensitive models do this. They are generally more realistic and more complicated than deterministic models, sometimes generate like predictions and, given the heuristic nature of the modeling effort, may not always be the preferred option for analysis . There is a well-developed literature regarding the risk-sensitive behavior of foragers and food producers, taken separately , but little has been written about risk sensitive adaptation during the transition from one of these subsistence systems to the other .The concepts just reviewed—marginal valuation, opportunity cost, discounting, and risk sensitive analysis—signal that behavioral ecology is an attempt to assess the costs and benefits of alternative courses of action under a range of environmental conditions. In operational terms, we accomplish this task with models that have in common four features: an alternative set, constraints, some form of currency, and a goal. Within a particular model, the range of possible behavioral actions is known as the alternative set. For instance, the diet breadth model specifies an alternative set of ranked combinations of potential resources . In the marginal value theorem, the alternative set refers to patch residence times. The alternative set is the dependent variable in the analysis; a particular socioenvironmental factor constitutes the independent variable. The model itself does not specify what might cause the independent variable to take on a certain value, or to change. It thus leaves open the opportunity for exploring how diverse influences such as habitat or climate change, seasonal variations in population density, over exploitation, competition from another predator or pressure to extract a surplus might affect a behavior like resource selection.