Nuclear Genomic Sequences Reveal that Polar Bears Are an Old and Distinct Bear Lineage
Nuclear Genomic Sequences Reveal that Polar Bears Are an Old and Distinct Bear Lineage
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DOI：
10.1126/science.1216424
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发表时间：
2012-04-20
期刊：
影响因子：
56.9
通讯作者：
Janke, Axel
中科院分区：
文献类型：
--
作者：
Hailer, Frank;Kutschera, Verena E.;Janke, Axel
最近的研究表明，北极熊母系（线粒体DNA）自晚更新世以来从棕熊谱系进化而来，可能表明快速的物种形成和对北极条件的适应。在这里，我们提出了一个高分辨率的数据集，从多个独立的基因座在核基因组的广泛样本的北极熊，棕熊和黑熊。贝叶斯结合分析将北极熊置于棕熊分支之外，并将分歧日期定得更早，在更新世中期，大约60万（338至934）年前。这为北极熊的进化提供了更多的时间，并证实了先前的建议，即北极熊由于过去的杂交而携带渗入的棕熊线粒体DNA。我们的研究结果强调了多位点基因组分析对于准确理解进化历史至关重要。
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.