Physiology and Genomic architecture of fine-scale adaptation

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Classically, the understanding of how genes influence resistance to environmental stress was based on the assumption that a few rare genes have large effects. An alternate idea is that there are many different genes that occur in many individuals, but each gene has a small effect. Adding up many genes of small effect ultimately results in a large response. This new idea changes the study of individual variation, its effects on human health, and the prediction about the future success of animals and plants. This research tests these ideas by comparing different populations exposed to different environmental stressors. Using these populations, the research team will determine the genetic differences among these populations and connect these genetic differences to physiological measurements. From these data, the team will determine the number of genes that influence the response to the environment and predict how individuals respond to environmental stress. The prediction is that there are a large number of genes that can alter an individual's response to environmental stress. If correct, this suggests that there are many different combinations of genes that work well to respond to the environment. Such a result would help resolve an unsolved question, why is genetic diversity so abundant in nature? Additionally, understanding, natural variation among healthy individuals will provide more accurate forecasts of how species will respond to a changing world. Finally, in addition to the research outcomes, the project will enhance educational opportunities for local community college students and train of graduate students in integrative organismal biology.How does adaption to stressful environments work, does it depend on new mutations or standing genetic variation, involve many loci of small effect or is it primarily due to a few genes of large effect? A better understanding of the nature of adaptation to the environment will provide more accurate predictions of how changing environments will affect species survival. For ecological and physiological processes, the classic hypothesis has been that adaptation involves one or a few genes, yet it seems likely that many genes affect fitness or biological processes that affect organisms' success. Although there is much debate, a potential major shift in our understanding of adaptive variation suggests that polygenic soft-sweeps involving many loci cause a selective advantage. Adaptation involving many loci is possible if many individuals carry alternative alleles in the ancestral population. With many alternative alleles at relatively high frequencies, adaptation is faster and less costly. The research proposed here will provide the necessary empirical data to address the frequency of polygenic soft-sweeps. In addition, the research will provide data to predict and quantify adaptive divergence. This research will specifically examine the temporal variation in high-throughput sequences among teleost fish Fundulus heteroclitus occupying different microhabitats and combines these with measures of physiological processes (CTmax, hypoxic-CTmax and cardiac metabolism). The research team will follow cohorts through time that occupy different microhabitats. These data address two goals: 1) determine if significant allele frequency differences across microhabitats are due to the selective loss of individuals over a single season, and 2) examine physiological consequences of altered allele frequencies. This award was co-funded by the Division of Integrative Organismal Systems, the Division of Environmental Biology, and the Rules of Life Venture Fund within The Directorate for Biological Sciences.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.