DISSERTATION RESEARCH: Delineation of populations, species, and genomic adaptations across a widely distributed venomous snake species complex

University Of Texas At Arlington, Arlington TX

Investigators

Abstract

Characterizing the diversity and relatedness of life is an important goal of evolutionary biology, and our understanding of this diversity provides a framework to address important questions. Many of these questions relate to adaptations that are evolved over time to better suit organisms to their environment. In particular, it is little understood whether the same evolutionary forces and processes may act in a similar manner to produce locally adapted traits in closely related lineages. Are certain genes or genomic regions repeatedly targeted by natural selection across species that occupy drastically different habitats and climates? This research aims to address these questions using a unique system of North American rattlesnakes, the Crotalus viridis species complex. Snakes of this group are highly diverse in their coloration, size, and venom composition, and thrive in diverse ecoregions. This research program will generate a robust understanding of the evolutionary relationships among members of this group, which will also provide a contextual framework for testing hypotheses of how natural selection has driven their diversification. This research program will then use information collected from throughout the genomes of these lineages to look for evidence of genes and sets of genes that are common targets of selection for local adaptation. Understanding the systematics of species complexes can be challenging, but new and robust analytical approaches, together with large genome-scale datasets from next-generation sequencing technology are making this challenge increasingly manageable. Despite the difficulties inherent in studying species complexes, these systems are ideal for linking our understanding of their biodiversity with the genomic processes that have shaped their evolution and diversity. This project seeks to make these connections using a comparative phylogenetic system, the Crotalus viridis species complex. The research program will generate the first robust species tree for the complex, which has historically been a problematic group for systematists, using genome-wide single nucleotide polymorphism data. This phylogenetic framework will then be used as a comparative platform for analyses of genes and genomic regions under selection within and among lineages. This research will interrogate the genomes of multiple populations and species to address the question of whether selection regimes target common loci across such a species complex, or if genes and functional categories of genes are idiosyncratically targeted by lineage. Collectively, this research will characterize the evolutionary history of a diverse and medically relevant venomous snake group and will add considerably to our knowledge of the roles that adaptation and convergent evolution play in the generation of biodiversity at multiple scales.