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Phenotypic assortment by morphology in social partners of the forked fungus beetle Bolitotherus cornutus


Brodie III, Edmund (2021), Phenotypic assortment by morphology in social partners of the forked fungus beetle Bolitotherus cornutus, Dryad, Dataset,


Social interactions with conspecifics can dramatically affect an individual’s fitness. The positive or negative consequences of interacting with social partners typically depend on the value of traits that they express. These pathways of social selection connect the traits and genes expressed in some individuals to the fitness realized by others, thereby altering the total phenotypic selection on and evolutionary response of traits across the multivariate phenotype. The downstream effects of social selection are mediated by the patterns of phenotypic assortment between focal individuals and their social partners (the interactant covariance, Cij , or the multivariate form, CI). Depending on the sign and magnitude of the interactant covariance, the direction of social selection can be reinforced, reversed, or erased. We report estimates of Cij from a variety of studies of forked fungus beetles to address the largely unexplored questions of consistency and plasticity of phenotypic assortment in natural populations. We found that phenotypic assortment of male beetles based on body size or horn length was highly variable among subpopulations, but that those differences also were broadly consistent from year to year. At the same time, the strength and direction of Cij changed quickly in response to experimental changes in resource distribution and social properties of populations. Generally, interactant covariances were more negative in contexts in which the number of social interactions was greater in both field and experimental situations. These results suggest that patterns of phenotypic assortment could be important contributors to variability in multilevel selection through their mediation of social selection gradients.

Usage Notes

These data describe observations of social partners in natural field studies and manipulated mesocosms experiments. Observation protocols and assessment of proximity partners are described in the text and associated references. Variable names and associated details of data processing are in the attached readme file "Brodie_Phenotypic_Assortment_JoH_Readme.txt"

Fig 6 data (ResourceDistribAssortment_20211101.csv) include two treatments of resources distribution (clumped, dispersed) and two time periods (1, 2) because groups were reciprocally switched between treatements at the midpoint. Condo refers to the test chamber.

Fig 7 data (2019_males_for_assortment_analysis.csv) include three "treatments" (NA is the initial grouping used to assess individual social behavior that led to the sorting in to social and asocial treatments). "*partner" variable reflect the avg values of social partners for an individual, weighted by number of times they were together.


National Science Foundation, Award: 135503