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1. Behavioral variation, adaptation, and evolution

   https://doi.org/doi:10.1037/0000011-011  

   Shelton, D. S.; Martins, E. P. (January 2017, APA)

   Individual animals behave differently from each other for myriad interrelated intrinsic and extrinsic reasons, and this behavioral variation is the raw substrate for evolutionary change. Behavioral varia- tion can both enhance and constrain long-term evolution (Foster, 2013), and it provides the basic materials on which natural and sexual selection can act. A rich body of historical experimental and conceptual foundations precedes many of the topics discussed. This classic literature is vast and impor- tant, and we encourage the reader to examine it in detail (e.g., Lehrman, 1953; Lorenz, 1971; Schnei- rla, 1966; Waddington, 1959) because we discuss more recent literature. For example, the study of the mechanisms that underlie behavioral variation has a divisive history, which involves carving out the relative contributions of genes and environment to a particular phenotype. Developmental systems and reaction-norm views challenged the issue of gene or environment by arguing that the interplay between genetic substrates and environmental inputs defined adaptive phenotypes across multiple contexts (Fos- ter, 2013; Gottlieb, 1991a, 1991b; Jablonka & Lamb, 2014). Identifying the interactional relationship between components permits researchers to under- stand how behavior becomes organized (Gottlieb, 1991a, 1991b) and can reveal links between indi- vidual variation and population-level persistence, species diversification (or stasis), and community dynamics (reviewed in Dingemanse & Wolf, 2013). Similarly, the study of individual differences has a rich history situated in the areas of behavioral genet- ics, sociobiology, behavioral ecology, developmen- tal psychology, personality theory, and studies of learning and cognition. Each area has its own goals, associated techniques, and levels of explanation. The study of behavioral variation during early develop- ment, for instance, has been documented primarily by psychologists studying proximate mechanisms in laboratory animal models, whereas the study of dif- ferent adult morphs using the adaptationist perspec- tive has been dominated by behavioral ecologists examining natural populations (Foster, 1995). A more complete description of individual differences requires an integrative study of the mechanisms (e.g., developmental, physiological) that guide intra- individual flexibility and the associated adaptive fine tuning of behavioral types. It is through this integra- tion that researchers can make predictions about the response of different individual phenotypes, groups, populations, and species to novel situations (e.g., captive and urban environments). 

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2. Soil microenvironmental variation drives below‐ground trait variation and interacts with macroclimate to structure above‐ground trait variation of arctic shrubs

   https://doi.org/10.1111/1365-2745.14278  

   Fraterrigo, Jennifer M; Chen, Weile; Loyal, Joshua; Euskirchen, Eugénie S (April 2024, Journal of Ecology)

   Henn, J (Ed.)

   Abstract Intraspecific trait variation can influence plant performance in different environments and may thereby determine the ability of individual plants to respond to climate change. However, our understanding of its patterns and environmental drivers across different spatial scales is incomplete, especially in understudied regions like the Arctic.To fill this knowledge gap, we examined above‐ground and below‐ground traits from three shrub taxa expanding across the tundra biome and evaluated their relationships with multiple microenvironmental and macroclimatic factors. The traits reflected plant size and structure (plant height, leaf area and root to shoot ratio), leaf economics (specific leaf area, nitrogen content), and root economics and collaboration with mycorrhizal fungi (specific root length, root tissue density, nitrogen content, and ectomycorrhizal colonisation intensity). We also measured leaf and root δ¹⁵N and leaf δ¹³C to characterise nitrogen source and acquisition pathways and plant water stress. Traits were measured in replicated plots (N = 135) varying in soil microclimate, thaw depth and organic layer thickness established across five sites spanning a macroclimate gradient in northern Alaska. This hierarchical design allowed us to disentangle the independent and combined effects of fine‐scale and broad‐scale factors on intraspecific trait variation.We found substantial intraspecific variation at fine spatial scales for most traits and less variation along the macroclimate gradient and between shrub taxa. Consistent with these patterns, microenvironmental factors, mainly soil moisture and thaw depth, interacted with macroclimate, mainly climatic water deficit, to structure size‐structural and leaf trait variation. In contrast, most root traits responded additively to thaw depth and macroclimate.Synthesis. Our results demonstrate that above‐ground and below‐ground tundra shrub traits respond differently to microenvironmental and macroclimatic variation. These differing responses contribute to substantial trait variation at fine spatial scales and may decouple above‐ground and below‐ground trait responses to climate change. 

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3. Genetic variation, environment and demography intersect to shape Arabidopsis defense metabolite variation across Europe

   https://doi.org/10.7554/eLife.67784  

   Katz, Ella; Li, Jia-Jie; Jaegle, Benjamin; Ashkenazy, Haim; Abrahams, R Shawn; Bagaza, Clement; Holden, Samuel; Pires, J Chris; Angelovici, Ruthie; Kliebenstein, Daniel J (May 2021, eLife)

   null (Ed.)

   Plants produce diverse metabolites to cope with the challenges presented by complex and ever-changing environments. These challenges drive the diversification of specialized metabolites within and between plant species. However, we are just beginning to understand how frequently new alleles arise controlling specialized metabolite diversity and how the geographic distribution of these alleles may be structured by ecological and demographic pressures. Here we measure the variation in specialized metabolites across a population of 797 natural Arabidopsis thaliana accessions. We show a combination of geography, environmental parameters, demography, and different genetic processes all combine to influence the specific chemotypes and their distribution. This showed that causal loci in specialized metabolism contain frequent independently generated alleles with patterns suggesting potential within species convergence. This provides a new perspective about the complexity of the selective forces and mechanisms that shape the generation and distribution of allelic variation that may influence local adaptation. 

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4. Selection on size variation: more variation in bumble bee workers and in the wild

   https://doi.org/10.1007/s00040-022-00850-y  

   Kelemen, E. P.; Skyrm, K.; Dornhaus, A. (February 2022, Insectes Sociaux)
5. Genetic variation, environment and demography intersect to shape Arabidopsis defense metabolite variation across Europe

   Katz, E.; Li jj; Jaegle, B.; Ashkenazy, H.; Abrahams SR.; Bagaza C.; Holden S.; Pires CJ.; Angelovici R.; Kliebenstein DJ. (May 2021, eLife)