Grant: Discovery Grants Program - Individual

Hybridization offers a unique window into the speciation process as the consequences of such interbreeding are potentially varied and, generally, unpredictable: ranging from reinforcement of genetic barriers, collapse of lineages, or movement of genetic regions between lineages (introgression). My long-term research goal is to understand the variability in genetic architecture of speciation by coupling genomic methods with analyses of hybridization in wild animal populations. My research program will pursue two short-term research objectives in two systems which I am developing: a contact zone of Arctic grayling (Thymallus arcticus) fish, and the rapid radiation of Galapagos tortoises (Chelonoidis sp.). Grayling are a member of the family Salmonidae and in North America there is one species of the genus, but two deeply divergent mitochondrial lineages, called Beringia and Nahanni. I have shown that the Beringia and Nahanni lineages co-occur within Alberta, Canada. However, it is unknown if there is contemporary hybridization. A hybrid zone is expected as examination of interspecific contact between other salmonids (eg. rainbow and cut-throat trout) suggest that hybridization is a common feature of this group. My lab will develop genomic markers for Arctic grayling to determine ancestry, identify hybrids, and assess the consequences of admixture. This data will then be coupled with detailed morphological information to look for signals of local adaptation between lineages. Galapagos tortoises are an icon of evolution and speciation whose radiation includes 14 named species and additional unnamed lineages. Within this radiation, cases of natural and anthropogenic hybridization between species exist, providing a series of pairwise admixture events in which to examine the genomic architecture of speciation. Leveraging genomic resources I have developed and an archive of tissue samples housed at Yale University, my lab will develop a single nucleotide polymorphism (SNP) panel for rapid assessment of ancestry and evidence of hybridization, which will allow us to select hybrid individuals for low-coverage whole genome sequencing to assess the architecture of hybridization. My research program has direct conservation and management implications for the species being studied as grayling are a species of Special Concern in Alberta, and all Galapagos tortoises are as Endangered or Critically Endangered by the International Union for Conservation of Nature. More broadly, evaluating the results and predictability of admixture in contemporary wild populations is important as climate change and anthropogenic movement of individuals cause species that were once isolated to encounter one another and potentially interbreed. These admixture events have significant management implications as hybridization is often considered a conservation threat. Thus, my research can help better frame these risks, leading to more robust conservation and management actions.