Moving, mixing, and making new species: Arctic evolutionary responses to Quaternary climate change

Speaker: Dr. Maria Dance, University of Cambridge
Series: Quaternary Discussion Group (QDG)

Quaternary glacial cycles drove profound biome reorganisations across the pan-Arctic, forcing tundra species to repeatedly shift ranges, fragment into isolated refugia, and reconnect along transient corridors like sea ice. Where traditional paleoecological proxies are sparse, contemporary population genomics provides a powerful lens to resolve these dynamic histories of divergence, hybridisation, and speciation.

In this talk, I draw on my PhD research examining how Quaternary climate oscillations shaped the evolutionary trajectories of two Arctic keystone species: reindeer/caribou (Rangifer tarandus) and dwarf birch (Betula nana). Using spatial patterns of present-day genetic variation, I modelled demographic histories to test competing hypotheses of glacial refugia and postglacial expansion. I validated model timelines against published subfossil, pollen, macrofossil, and sedimentary ancient DNA (sedaDNA) records, comparing these population events directly with independent ice sheet and sea ice reconstructions.

Integrating phylogeography with multi-proxy Quaternary records shows how past isolation and gene flow governed species resilience, offering vital insights into the long-term ecological and evolutionary consequences of anthropogenic warming in the Arctic.