Dissertation Defence: The Genomic Basis of Adaptation and Vulnerability to Climate Change in the American Pika (Ochotona Princeps)

Danielle Schmidt, supervised by Dr. Michael Russello, will defend their dissertation titled “The Genomic Basis of Adaptation and Vulnerability to Climate Change in the American Pika (Ochotona Princeps)” in partial fulfillment of the requirements for the degree of Doctor of Philosophy in Biology.

An abstract for Danielle Schmidt’s dissertation is included below.

Examinations are open to all members of the campus community as well as the general public. Please email michael.russello@ubc.ca to receive the Zoom link for this defence.

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ABSTRACT

Understanding the role of adaptation in species responses to climate change is important for estimating adaptive potential and informing conservation efforts. Population genomics enables estimates of population structure and connectivity, but also provides insights into the influence of historical climate fluctuations on species distributions. Further, these data allow for the identification of putatively adaptive genomic variation, which can be used to evaluate species’ adaptive potential. This is especially useful for organisms where direct tests for selection through common gardens or reciprocal transplant experiments are unfeasible. The American pika (Ochotona princeps) is a primarily high-elevation lagomorph distributed across western North America that has persisted across much of its current distribution through multiple glacial periods and is considered a sentinel species for the ecological effects of climate change. Here, I perform a multi-scaled investigation of the phylogenetic history of the American pika, as well as the genetic basis for adaptation and the genomic vulnerability of this species in response to changing environments. I generated restriction site-associated DNA sequencing (RADseq) data from samples collected across the entire range of American pikas, spanning latitudinal and elevational gradients at multiple spatial scales. Relative to previous molecular analyses of mitochondrial DNA (mtDNA), phylogenetic analyses performed using neutral single nucleotide polymorphisms (SNPs) identified a new genetic break, resulting in six major phylogenetic groups of pikas across the species distribution. Range-wide, patterns of adaptive variation inferred from putatively adaptive SNPs followed a latitudinal gradient, with highest genomic vulnerability predicted among populations in Oregon that were associated with a large decrease in winter radiation. Within the Cascades lineage, I found evidence for adaptive divergence between populations at high and low elevations along three independent elevational transects, despite evidence for gene flow. Collectively, this thesis provides evidence for climate-mediated adaptation in American pikas at various spatial scales. More broadly, it highlights the utility of population genomics for guiding conservation, particularly in the face of rapid climate change.