Holocene deglaciation drove rapid genetic diversification of Atlantic walrus

Emily J. Ruiz-Puerta*, Xénia Keighley, Sean P.A. Desjardins, Anne Birgitte Gotfredsen, Shyong En Pan, Bastiaan Star, Sanne Boessenkool, James H. Barrett, Morgan L. McCarthy, Liselotte W. Andersen, Erik W. Born, Lesley R. Howse, Paul Szpak, Snæbjörn Pálsson, Hilmar J. Malmquist, Scott Rufolo, Peter D. Jordan, Morten Tange Olsen*

*Corresponding author for this work

Research output: Contribution to journal/Conference contribution in journal/Contribution to newspaperJournal articleResearchpeer-review

1 Citation (Scopus)

Abstract

Rapid global warming is severely impacting Arctic ecosystems and is predicted to transform the abundance, distribution and genetic diversity of Arctic species, though these linkages are poorly understood. We address this gap in knowledge using palaeogenomics to examine how earlier periods of global warming influenced the genetic diversity of Atlantic walrus (Odobenus rosmarus rosmarus), a species closely associated with sea ice and shallow-water habitats. We analysed 82 ancient and historical Atlantic walrus mitochondrial genomes (mitogenomes), including now-extinct populations in Iceland and the Canadian Maritimes, to reconstruct the Atlantic walrus' response to Arctic deglaciation. Our results demonstrate that the phylogeography and genetic diversity of Atlantic walrus populations was initially shaped by the last glacial maximum (LGM), surviving in distinct glacial refugia, and subsequently expanding rapidly in multiple migration waves during the late Pleistocene and early Holocene. The timing of diversification and establishment of distinct populations corresponds closely with the chronology of the glacial retreat, pointing to a strong link between walrus phylogeography and sea ice. Our results indicate that accelerated ice loss in the modern Arctic may trigger further dispersal events, likely increasing the connectivity of northern stocks while isolating more southerly stocks putatively caught in small pockets of suitable habitat.

Original languageEnglish
Article number20231349
JournalProceedings of the Royal Society B: Biological Sciences
Volume290
Issue2007
Number of pages11
ISSN0962-8452
DOIs
Publication statusPublished - Sept 2023

Keywords

  • ancient DNA
  • Arctic
  • environmental change
  • marine mammals
  • Odobenus rosmarus rosmarus
  • palaeogenetics

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