At high latitudes, climatic oscillations have triggered repeated episodes of organismal divergence by geographically isolating populations. For terrestrial species, extended isolation in glacial refugia – ice-free regions that enable terrestrial species persistence through glacial maxima – is hypothesized to stimulate allopatric divergence. Alternatively, upon glacial recession, divergent populations expanded from independent glacial refugia and often contacted other diverging populations. In the absence of reproductive isolating mechanisms, this biogeographic process may trigger hybridization and ultimately, gene flow between divergent taxa. My dissertation research aims to understand how these episodic periods of isolation and contact have impacted the evolution of high latitude species. To understand the role of episodic isolation and gene flow on the evolution and diversification of high-latitude species, my dissertation integrates genetic, genomic, and morphometric characters across multiple high-latitude mesocarnivore mammals within the hyper-diverse Mustelidae family. Overall, I identified substantial cryptic diversity in the Arctic and highlight the complementary roles of glacial and interglacial cycles in the evolution and structuring of high latitude biota
