Unbound MEDLINE

Nuclear genomic sequences reveal that polar bears are an old and distinct bear lineage.

Abstract

Recent studies have shown that the polar bear matriline (mitochondrial DNA) evolved from a brown bear lineage since the late Pleistocene, potentially indicating rapid speciation and adaption to arctic conditions. Here, we present a high-resolution data set from multiple independent loci across the nuclear genomes of a broad sample of polar, brown, and black bears. Bayesian coalescent analyses place polar bears outside the brown bear clade and date the divergence much earlier, in the middle Pleistocene, about 600 (338 to 934) thousand years ago. This provides more time for polar bear evolution and confirms previous suggestions that polar bears carry introgressed brown bear mitochondrial DNA due to past hybridization. Our results highlight that multilocus genomic analyses are crucial for an accurate understanding of evolutionary history.

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  • Authors

    Hailer F, Kutschera VE, Hallström BM, Klassert D, Fain SR, Leonard JA, Arnason U, Janke A

    Source

    Science (New York, N.Y.) 336:6079 2012 Apr 20 pg 344-7

    MeSH

    Animals
    Bayes Theorem
    Biological Evolution
    Cell Nucleus
    DNA, Mitochondrial
    Gene Flow
    Genetic Speciation
    Genetic Variation
    Genome
    Haplotypes
    Hybridization, Genetic
    Molecular Sequence Data
    Multilocus Sequence Typing
    Phylogeny
    Ursidae

    Pub Type(s)

    Journal Article
    Research Support, Non-U.S. Gov't

    Language

    eng

    PubMed ID

    22517859