Kuo Hao-Chih, Chen Shiang-Fan, Fang Yin-Ping, Cotton James A, Parker Joe D, Csorba Gábor, Lim Burton K, Eger Judith L, Chen Chia-Hong, Chou Cheng-Han, Rossiter Stephen J
School of Biological and Chemical Sciences, Queen Mary University of London, London, E1 4NS, UK.
Center for General Education, National Taipei University, New Taipei City, 23741, Taiwan.
Mol Ecol. 2015 Dec;24(23):5910-26. doi: 10.1111/mec.13425. Epub 2015 Nov 20.
Cases of geographically restricted co-occurring sister taxa are rare and may point to potential divergence with gene flow. The two bat species Murina gracilis and Murina recondita are both endemic to Taiwan and are putative sister species. To test for nonallopatric divergence and gene flow in these taxa, we generated sequences using Sanger and next-generation sequencing, and combined these with microsatellite data for coalescent-based analyses. MtDNA phylogenies supported the reciprocally monophyletic sister relationship between M. gracilis and M. recondita; however, clustering of microsatellite genotypes revealed several cases of species admixture suggesting possible introgression. Sequencing of microsatellite flanking regions revealed that admixture signatures stemmed from microsatellite allele homoplasy rather than recent introgressive hybridization, and also uncovered an unexpected sister relationship between M. recondita and the continental species Murina eleryi, to the exclusion of M. gracilis. To dissect the basis of these conflicts between ncDNA and mtDNA, we analysed sequences from 10 anonymous ncDNA loci with *beast and isolation-with-migration and found two distinct clades of M. eleryi, one of which was sister to M. recondita. We conclude that Taiwan was colonized by the ancestor of M. gracilis first, followed by the ancestor of M. recondita after a period of allopatric divergence. After colonization, the mitochondrial genome of M. recondita was replaced by that of the resident M. gracilis. This study illustrates how apparent signatures of sympatric divergence can arise from complex histories of allopatric divergence, colonization and hybridization, thus highlighting the need for rigorous analyses to distinguish between such scenarios.
地理分布受限的共生姐妹分类群的情况很少见，可能表明存在基因流情况下的潜在分化。两种蝙蝠物种，即纤细管鼻蝠（Murina gracilis）和隐管鼻蝠（Murina recondita）均为台湾特有种，被认为是姐妹物种。为了检验这些分类群中的非异域分化和基因流情况，我们使用桑格测序法和新一代测序技术生成了序列，并将这些序列与微卫星数据相结合，用于基于溯祖理论的分析。线粒体DNA系统发育分析支持了纤细管鼻蝠和隐管鼻蝠之间相互单系的姐妹关系；然而，微卫星基因型聚类显示出几例物种混合的情况，表明可能存在基因渐渗。微卫星侧翼区域的测序表明，混合特征源于微卫星等位基因的同塑性，而非近期的渐渗杂交，并且还发现了隐管鼻蝠与大陆物种艾氏管鼻蝠（Murina eleryi）之间意外的姐妹关系，而纤细管鼻蝠不在此列。为了剖析这些核DNA（ncDNA）与线粒体DNA（mtDNA）之间冲突产生的基础，我们使用贝叶斯进化分析采样树（beast）和迁移隔离模型分析了来自10个匿名核DNA位点的序列，发现艾氏管鼻蝠有两个不同的分支，其中一个分支是隐管鼻蝠的姐妹分支。我们得出结论，台湾首先被纤细管鼻蝠的祖先所殖民，在经历一段时间的异域分化后，隐管鼻蝠的祖先才到来。殖民之后，隐管鼻蝠的线粒体基因组被当地的纤细管鼻蝠的线粒体基因组所取代。这项研究说明了异域分化、殖民和杂交的复杂历史是如何产生同域分化的明显特征的，从而强调了进行严格分析以区分这些情况的必要性。
