DISSERTATION RESEARCH: Examining Evidence for Phenotypic and Genetic Convergence in the Guppy (Poecilia reticulata)

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Convergent evolution refers to the origin of similar traits in different species, such as flight in birds, bats, and insects. It is often thought that the genes underlying convergent evolution within species are similar, but this is still an open question. This proposal uses a nucleic acid sequencing method to which genes are turned on or off at any time. This information is then compared with tail color patterns of guppies. Tail coloration is highly variable trait and plays a key role in mating displays. The project will identify color genes in different fish at different locations to understand if the same genetic signatures result in similar patterns. The study will advance scientific knowledge by answering questions concerning the predictability of evolution, and will provide research opportunities for undergraduates at one of the most ethnically diverse universities in the nation. This proposal focuses on convergent evolution. Specifically, the researchers address two questions: 1) How similar are visible color patterns among individuals from genetically diverged populations? and 2) Will genes differentiating extreme color patterns within a population be convergent among individuals from genetically diverged sites, and if so, which ones? For the first question, the researchers will analyze photographs of male guppies from five sites and sort the patterns into color categories. The researchers hypothesize that there will be convergence in the color patterns of males from genetically diverged populations. The second question will be answered using next generation DNA sequencing. For each of the five sites, tissues from males with colored and uncolored tails will be sequenced. The differentially expressed genes between tail color types at one site will be compared to the differentially expressed genes between tail color types at the other sites to test for convergence. The researchers will be able to determine if phenotypic convergence is correlated with expression of the same genes, different genes within the same pathway, or different pathways.