Ancient horse genomes reveal the timing and extent of dispersals across the Bering Land Bridge
Creators
- Vershinina, Alisa1
- Heintzman, Peter2
- Froese, Duane3
- Zazula, Grant4
- Cassatt-Johnstone, Molly1
- Dalén, Love5
- Der Sarkissian, Clio6
- Dunn, Shelby1
- Ermini, Luca7
- Gamba, Cristina7
- Groves, Pamela8
- Kapp, Joshua1
- Mann, Daniel8
- Seguin-Orlando, Andaine6
- Southon, John9
- Stiller, Mathias1
- Wooller, Matthew8
- Baryshnikov, Gennady10
- Gimranov, Dmitry11
- Scott, Eric12
- Hall, Elizabeth13
- Hewitson, Susan13
- Kirillova, Irina10
- Kosintsev, Pavel11
- Shidlovsky, Fedor14
- Tong, Hao-Wen15
- Tiunov, Mikhail16
- Vartanyan, Sergey16
- Orlando, Ludovic6
- Corbett-Detig, Russ1
- Macphee, Ross17
- Shapiro, Beth1
- 1. University of California, Santa Cruz
- 2. The Arctic University of Norway
- 3. University of Alberta
- 4. Canadian Museum of Nature
- 5. Swedish Museum of Natural History
- 6. Paul Sabatier University
- 7. University of Copenhagen
- 8. University of Alaska Fairbanks
- 9. University of California, Irvine
- 10. Russian Academy of Sciences
- 11. Ural Branch of the Russian Academy of Sciences
- 12. California State University, San Bernardino
- 13. Government of Yukon, Department of Tourism and Culture, Palaeontology Program, Whitehorse*
- 14. National Alliance of Shidlovskiy "Ice Age"*
- 15. Chinese Academy of Sciences
- 16. Far East Branch of the Russian Academy of Sciences
- 17. American Museum of Natural History
Description
The Bering Land Bridge (BLB) last connected Eurasia and North America during the Pleistocene. Although the BLB would have enabled transfers of terrestrial biota in both directions, it also acted as an ecological filter whose permeability varied considerably over time. Here we explore the possible impacts of this ecological corridor on genetic diversity within, and connectivity among, populations of a once wide-ranging group, the caballine horses (Equus spp.). Using a panel of 187 mitochondrial and eight nuclear genomes recovered from present-day and extinct caballine horses sampled across the Holarctic, we found that Eurasian horse populations initially diverged from those in North America, their ancestral continent, around 1.0-0.8 million years ago. Subsequent to this split our mitochondrial DNA analysis identified two bi-directional long-range dispersals across the BLB ~875-625 and ~200-50 thousand years ago, during the Middle and Late Pleistocene. Whole genome analysis indicated low levels of gene flow between North American and Eurasian horse populations, which likely occurred as a result of these inferred dispersals. Nonetheless, mitochondrial and nuclear diversity of caballine horse populations retained strong phylogeographic structuring. Our results suggest that barriers to gene flow, currently unidentified but possibly related to habitat distribution across Beringia or ongoing evolutionary divergence, played an important role in shaping the early genetic history of caballine horses, including the ancestors of living horses within Equus ferus.
Notes
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Vershinina_etal_2021_BLB_horses.zip
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