DISSERTATION RESEARCH:: Genetic sources of novel jaw morphology among Bahamian pupfish (genus Cyprinodon)

Cornell University, Ithaca NY

Investigators

Abstract

Understanding the origins of evolutionary novelty is fundamental to the study of biological diversity. Many studies have focused on the role of selection in driving change. However, a complete picture of the evolutionary process must also account for the mechanisms that create variation. This project investigates genetic changes that produce variation in the jaws of a recently diverged group of fish, and will provide insight into the nature of genetic changes associated with evolution in wild populations. The work will train a graduate in genomic research, and provide research opportunities for undergraduate students interested in careers in science. The researchers will create materials designed for use in K-12 classrooms about fish evolution that highlight how evolutionary novelties arise. The researchers will investigate the genetic and developmental basis of cranial modifications in recently diverged incipient species of Bahamian pupfish (Cyprinodon). The work addresses the role of gene regulation and sequence divergence in producing novel phenotypic change associated with speciation in three closely-related species that specialize on eating either the scales of other fish or hard-shelled prey or detritus. The project will identify whether the genes and regulatory changes producing pupfish jaw diversity are homologous to those identified in other classic radiations, thus informing our understanding of the extent to which similar genetic mechanisms underlie phenotypic change in disparate lineages. Importantly, the project also aims to identify previously unknown genes associated with evolutionary changes to jaw morphology. The researchers will use high throughput sequencing (RNA-seq) to characterize the extent of regulatory divergence and sequence divergence among the Bahamian forms and the widespread marine outgroup. They will investigate how patterns of transcriptional regulation have diverged among Bahamian forms and identify gene regulatory changes associated with the diversification of jaw morphology. These data will, furthermore, be used to identify sequence variation (SNPs) associated with phenotypic divergence and reproductive isolation in the system. This project will thus provide insight into the genetic changes associated with speciation and the evolution of morphological novelties during the early stages of diversification.