Ancient hybridization and mitochondrial capture between two species of chipmunks
Ancient hybridization and mitochondrial capture between two species of chipmunks
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DOI：
10.1111/j.1365-294x.2007.03640.x
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发表时间：
2008-03-01
影响因子：
4.9
通讯作者：
Sullivan, Jack
中科院分区：
文献类型：
--
作者：
Good, Jeffrey M.;Hird, Sarah;Sullivan, Jack
在面对基因流动时，假设物种形成的模型正在取代传统观点，即动物物种之间的杂交是罕见的。我们使用多位点方法来研究两种花栗鼠（Tamias ruficaudus和T. amoenus）之间的杂交历史和基因流动。先前的研究表明，这些物种占据不同的生态位，具有不同的生殖骨形态，但似乎在多个共感区繁殖不完全隔离。我们将4个测序的核位点和7个微卫星位点的数据与已发表的细胞色素b序列进行了比较。种间基因流动主要局限于T. ruficaudus线粒体基因组向同域亚种T. a.c anicaudus的渗入，4个测序的核位点显示很少或没有种间等位基因共享。微卫星数据与物种之间的高度分化相一致，并且还显示在广泛同域的T. canicaudus和T. ruficaudus种群之间没有当前的基因流动。荧光分析确定了中更新世至上新世晚期的mtDNA渗入事件。总的来说，这些数据表明，尽管有多个独立的杂交事件，渗入对T. amoenus和T. ruficaudus的核基因组的影响很小。我们的发现挑战了长期以来对花栗鼠生殖隔离模式的假设，并表明在北美西部的23种塔米亚中可能存在其他杂交的例子。
Models that posit speciation in the face of gene flow are replacing classical views that hybridization is rare between animal species. We use a multilocus approach to examine the history of hybridization and gene flow between two species of chipmunks (Tamias ruficaudus and T. amoenus). Previous studies have shown that these species occupy different ecological niches and have distinct genital bone morphologies, yet appear to be incompletely isolated reproductively in multiple areas of sympatry. We compared data from four sequenced nuclear loci and from seven microsatellite loci to published cytochrome b sequences. Interspecific gene flow was primarily restricted to introgression of the T. ruficaudus mitochondrial genome into a sympatric subspecies of T. amoenus, T. a. canicaudus, with the four sequenced nuclear loci showing little to no interspecific allele sharing. Microsatellite data were consistent with high levels of differentiation between the species and also showed no current gene flow between broadly sympatric populations of T. a. canicaudus and T. ruficaudus. Coalescent analyses date the mtDNA introgression event from the mid-Pleistocene to late Pliocene. Overall, these data indicate that introgression has had a minimal impact on the nuclear genomes of T. amoenus and T. ruficaudus despite multiple independent hybridization events. Our findings challenge long-standing assumptions on patterns of reproductive isolation in chipmunks and suggest that there may be other examples of hybridization among the 23 species of Tamias that occur in western North America.