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

• Published in: Molecular Ecology
• Main Authors: Vershinina, Alisa, Heintzman, Peter D., Froese, Duane G., Zazula, Grant D., Cassatt-Johnstone, Molly, Dalén, Love, Der Sarkissian, Clio, Dunn, Shelby G., Ermini, Luca, Gamba, Cristina, Groves, Pamela, Kapp, Joshua D., Mann, Daniel H., Seguin-Orlando, Andaine, Southon, John R., Stiller, Mathias, Wooller, Matthew J., Baryshnikov, Gennady, Gimranov, Dmitry, Scott, Eric, Hall, Elizabeth, Hewitson, Susan, Kirillova, Irina V., Kosintsev, Pavel, Shidlovsky, Fedor, Tong, Hao-Wen, Tiunov, Mikhail P., Vartanyan, Sergey, Orlando, Ludovic, Corbett-Detig, Russell B., MacPhee, Ross D. E., Shapiro, Beth
• Format: Article in Journal/Newspaper
• Language: English
• Published: Wiley 2021
• Subjects: Bering Land Bridge; Beringia
• Online Access: https://hdl.handle.net/10037/24463; https://doi.org/10.1111/mec.15977

This is the peer reviewed version of the following article: Vershinina AO, Heintzman PD, Froese DG, et al. Ancient horse genomes reveal the timing and extent of dispersals across the Bering Land Bridge. Mol Ecol. 2021;30:614 4–6161, which has been published in final form at https://doi.org/10.1111/mec.15977. This article may be used for non-commercial purposes in accordance with Wiley Terms and Conditions for Use of Self-Archived Versions. This article may not be enhanced, enriched or otherwise transformed into a derivative work, without express permission from Wiley or by statutory rights under applicable legislation. Copyright notices must not be removed, obscured or modified. The article must be linked to Wiley’s version of record on Wiley Online Library and any embedding, framing or otherwise making available the article or pages thereof by third parties from platforms, services and websites other than Wiley Online Library must be prohibited. 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.