Ancient horse genomes reveal the timing and extent of dispersals across the Bering Land Bridge

Alisa O. Vershinina*, Peter D. Heintzman, Duane G. Froese, Grant Zazula, Molly Cassatt-Johnstone, Love Dalén, Clio Der Sarkissian, Shelby G. Dunn, Luca Ermini, Cristina Gamba, Pamela Groves, Joshua D. Kapp, Daniel H. Mann, Andaine Seguin-Orlando, John Southon, Mathias Stiller, Matthew J. Wooller, Gennady Baryshnikov, Dmitry Gimranov, Eric ScottElizabeth Hall, Susan Hewitson, Irina Kirillova, Pavel Kosintsev, Fedor Shidlovsky, Hao Wen Tong, Mikhail P. Tiunov, Sergey Vartanyan, Ludovic Orlando, Russell Corbett-Detig, Ross D. MacPhee, Beth Shapiro

*Corresponding author for this work

Research output: Contribution to journalArticleResearchpeer-review

19 Citations (Scopus)

Abstract

The Bering Land Bridge (BLB) last connected Eurasia and North America during the Late 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 bidirectional 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 probably occurred as a result of these inferred dispersals. Nonetheless, mitochondrial and nuclear diversity of caballine horse populations retained strong phylogeographical 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.

Original languageEnglish
Pages (from-to)6144-6161
Number of pages18
JournalMolecular Ecology
Volume30
Issue number23
DOIs
Publication statusPublished - Dec 2021
Externally publishedYes

Keywords

  • Bering Land Bridge
  • Equus ferus
  • horses
  • palaeogenomics
  • population structure

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