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Evolutionary history of brown and polar bears

Hailer, F.; Welch, A.J.

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Authors

F. Hailer



Abstract

Taxonomists have long recognised polar and brown bears as separate species with distinct ecological niches and largely nonoverlapping ranges. Surprisingly, phylogenetic studies of maternally inherited mitochondrial DNA (mtDNA) found polar bears nested within brown bears, with an estimated divergence time of <170 000 years. This indicated an unusually rapid speciation and adaptation of polar bears. However, several recent studies of autosomal and Y‐chromosomal DNA have revisited these findings, giving independent perspectives of bear evolutionary history. Results show that polar bears cluster separately from brown bears, and divergence time estimates are older than those based on mtDNA, ranging from >300 000 to 4–5 million years. These studies confirm uniqueness of the polar bear lineage, provide more time for speciation and adaptation, and have uncovered numerous candidate genes for evolutionary adaptations. Several instances of introgressive hybridisation between polar and brown bears have been inferred, revealing trans‐species transmission of mtDNA and some nuclear loci.

Citation

Hailer, F., & Welch, A. (2016). Evolutionary history of brown and polar bears. In Encyclopedia of life sciences (1-8). John Wiley and Sons. https://doi.org/10.1002/9780470015902.a0026303

Publication Date Jul 15, 2016
Deposit Date Apr 6, 2016
Publicly Available Date Apr 13, 2016
Pages 1-8
Book Title Encyclopedia of life sciences.
ISBN 9780470015902
DOI https://doi.org/10.1002/9780470015902.a0026303
Public URL https://durham-repository.worktribe.com/output/1667023
Contract Date Mar 31, 2016

Files

Accepted Book Chapter (3.4 Mb)
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Copyright Statement
This is the accepted version of the following article: Hailer, F. & Welch, A.J. (15 July 2016). Evolutionary history of brown and polar bears. eLS. John Wiley & Sons Ltd, Chichester, which has been published in final form at https://doi.org/10.1002/9780470015902.a0026303. This article may be used for non-commercial purposes in accordance With Wiley Terms and Conditions for self-archiving.





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