DISSERTATION RESEARCH: Hybrid zone formation and comparative genomic divergences in South American lizards (Iguania: Liolaemidae)

University Of Washington, Seattle WA

Investigators

Abstract

Hybrid zones are geographical areas where hybrid offspring have mixed genetic composition and physical appearances compared to their parent populations/species. By studying genomic divergence in hybrid zones, researchers can better understand which differences are responsible for the formation of new species, and also the genomic regions that separate species. Such knowledge is relevant to many fields beyond systematics, including ecology, conservation biology, and even agriculture. This research project focuses on species within the South American lizard genus, Liolaemus, and uses genomic tools to investigate the age of hybrid zones, how they form, and how natural and sexual selection maintain genetic boundaries. Although many hybrid zones have been studied in northern temperate systems, southern temperate systems have received comparatively little attention. This research will train one graduate student in diverse systematic methods and undergraduates in field, laboratory and analytical methods. The project will also enhance international scientific infrastructure through collaborations with Argentinian researchers. Results from this research will be broadly disseminated through displays and presentations at the Burke Museum of Natural History and Culture in Seattle, WA. The proposed research will investigate hybridization and comparative species divergences across three species pairs in the Liolaemus fitzingerii group. In part, the hypothesis will be tested that these hybrid zones have formed due to secondary contact following post-glacial range expansions approximately 12,000 years ago. Genome-wide single nucleotide polymorphism (SNP) data will be generated using the restriction site-associated DNA sequencing (RADseq) method to estimate the genetic and geographic transitions between species in three separate hybrid zones. SNP data will also be used to estimate evolutionary relationships and delimit species. Aligning the SNP data to an annotated genome will enable the identification of regions of the genome that are involved in maintaining species boundaries in this group. Together, these data will shed new light on the genomic changes that occur within hybrid zones, and provide novel insights into the mechanisms driving the formation of new species.