Long-Term Investigation of Evolution in a Community Context

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Understanding the diverse and simultaneous pressures experienced by species within a community may provide insights not readily gathered from the study of pair-wise interactions between species. All species are part of multi-species communities and the traits they express are shaped by selective pressures generated by the web of direct and indirect interactions among community members, along with the effects of abiotic factors. Selective pressures from multiple sources are often termed 'diffuse.' In the proposed work, several criteria that have been proposed to identify diffuse selection exerted by whole communities will be explored. These criteria are summarized briefly here as: the genetic correlation between traits acted on by multiple community members, the effects of one species that alter the likelihood or intensity of interactions with other community members, and the presence of non-additive effects on the relationship between trait values and fitness; this non-additivity should be caused by the combination of selective effects imposed by multiple species. Experimental field manipulations of putative selective agents are combined with observational demographic data and with greenhouse crossing experiments in this long-term study of the diverse agents acting on flower color in the wild radish Raphanus sativus. This study is one of only a handful that examines experimentally the response to selection over long time periods and from multiple interactors in the field. As such it provides rare insights into trait evolution and conflicting selection in field settings. This proposal will train undergraduates and a graduate student. In the prior grant, students and professionals at all stages - undergrad, graduate student and post-doc were mentored and were authors on the published work. Many of these (6/9) were women, and all of the women have continued in science or science education. Overall, the lab has had a strong record of mentoring a range of under-represented groups in science, as summarized in the proposal.