DISSERTATION RESEARCH: Investigating patterns and processes of evolution, ecology, and diversification in carangiform fishes

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This project examines genetic diversity in two species of iconic marine fishes, the Giant Trevally and the Bluefin Trevally. Both species are top predators on coral and rocky reefs throughout the Indian and Pacific Oceans and are highly valued for artisanal, commercial, and sport fisheries. The research will investigate the correlation between genetic diversity and environmental variables (e.g., ocean temperature and currents) in the Indo-Pacific to identify physical barriers that might lead to observed differences in the genomes of these fishes in different geographic locations. The project focuses on the western Indian Ocean, a region lacking sufficient marine conservation measures in large part due to a scarcity of data necessary to inform governments making management decisions. Given the lack of data on these two species of Trevally, coupled with their economic importance, this project has direct societal implications. The researchers will share data with governmental and non-profit collaborators and incorporate strong scientific training components for graduate students, as well as engagement with members of the public in the USA, South Africa, and Seychelles. To accomplish the project objectives, the researchers will first conduct seascape genetic analyses using next generation sequencing techniques, specifically double digest restriction site associated DNA sequencing (RADseq) targeting single nucleotide polymorphisms (SNPs) to examine fine-scale genetic structure within and among C. ignobilis and C. melampygus individuals across their range. Seascape properties will be analyzed using coupled biological-physical models that integrate oceanographic data with biological attributes of these species. Models will be generated that maximize the availability of oceanographic information at a spatial scale complementary to the genetic data. The second component includes a phylogeographic analysis focused on characterizing patterns of historic gene flow by using paleoclimatic data to characterize physical and biological forces that may have driven evolution and influenced historical and present data distributions of the two species. This methodology uses high-resolution paleoceanographic models coupled with contemporary GIS-based species distribution modeling algorithms to generate paleodistribution suitability values for each species. These paleodistributions serve as alternate hypotheses to test against the SNP dataset. In combination, these analyses will provide insight on contemporary and historical processes shaping the diversification and connectivity of these two important fishery species.