DISSERTATION RESEARCH: Harnessing genomics to test the mechanisms causing adaptive phenotypic divergence along elevational gradients in a poison frog.

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This project investigates how environmental conditions along mountainsides leads to genetic change and divergence among different frog populations. Identifying the mechanisms by which populations genetically diverge, and eventually become separate species, is important for understanding the origins of biological diversity. Ecological differences along environmental gradients can drive divergence among populations. This project will identify the genes responsible for genetic divergence of trait values among populations of Anthony?s poison arrow frog, Epipedobates anthonyi, which occurs along multiple mountainsides and elevation gradients in Ecuador. The researchers will test for natural selection on genes and relate that selection to environmental factors so as to determine which are responsible for the observed divergence. The results will contribute to our understanding of why tropical systems are so diverse and help predict evolutionary responses to climate change. In addition, the project includes the training of undergraduates, educational workshops, and K-12 outreach activities. This project takes advantage of a unique study system to investigate the drivers and mechanisms that promote population divergence in the absence of geographic isolation. Populations of Epipedobates anthonyi show phenotypic divergence along elevation gradients in putatively adaptive traits including size, coloration, male advertisement calls, and thermal tolerance. Despite this phenotypic divergence, analyses of neutral genetic variation indicate that these populations are not isolated. Using genomic approaches, the researchers will examine signatures of divergent selection across the genome, correlate environmental variation with the observed divergence, and detect genetic changes likely responsible for observed phenotypic variation across elevation gradients. Tissue samples have been collected from 35 populations that encompass the distribution of this species across four replicated elevational gradients. This highly integrative project will provide an in-depth analysis of the relative roles of adaptive genetic differentiation and phenotypic plasticity on observed patterns of phenotypic divergence in natural populations.