Unexpected hybridization patterns in Near Eastern terrapins (Mauremys caspica, M. rivulata) indicate ancient gene flow across the Fertile Crescent
Unexpected hybridization patterns in Near Eastern terrapins (Mauremys caspica, M. rivulata) indicate ancient gene flow across the Fertile Crescent
复制标题
DOI：
10.1111/zsc.12227
复制
发表时间：
2017-07
影响因子：
2.5
通讯作者：
M. Vamberger;H. Stuckas;Mario Vargas-Ramírez;C. Kehlmaier;D. Ayaz;A. Aloufi;P. Lymberakis;P. Široký;U. Fritz
中科院分区：
文献类型：
--
作者：
M. Vamberger;H. Stuckas;Mario Vargas-Ramírez;C. Kehlmaier;D. Ayaz;A. Aloufi;P. Lymberakis;P. Široký;U. Fritz
最近的研究表明，动物中的杂交发生的频率比以前想象的要高，并且它可能发挥着重要的进化作用。龟类能够进行广泛的杂交，这提出了龟类物种如何进化并在杂交的情况下保持遗传完整性的问题。在这里，我们使用两个具有近邻分布的姐妹物种，Mauremys caspica 和 M. rivulata 作为我们的模型。据估计，这些类群在大约 5.3-700 万年前就已经分化。使用范围采样和 13 个未连锁的多态性微卫星标记、5 个核基因座和 1 个线粒体基因，我们表明土耳其两个物种的接触带上的杂交很少见。然而，我们在黎凡特南部发现了一个意想不到的混合群，迄今为止已被确认为M. rivulata。这个混合群与内陆物种 M. caspica 之间有 700 公里宽的分布间隙，相当于叙利亚沙漠。生态古模型表明，在末次盛冰期和全新世中期更加潮湿的气候时期，当前的接触带延伸到黎凡特南部，促进了现在孤立的混合群的建立。我们的结果表明，在给定的物种对中不一定存在一般的杂交模式，并且基因流的程度在分布范围的不同部分可能有很大差异。此外，我们的结果强调，杂交研究不应仅关注现存的接触和杂交区域，而应使用范围采样来检测可能会被错过的古代杂交信号。
Recent studies indicate that hybridization in animals occurs more frequently than previously thought and that it may play an important evolutionary role. Chelonians are capable of extensive hybridization, raising the question how chelonian species evolve and maintain genetic integrity despite hybridization. Here, we use two sister species with parapatric distribution, Mauremys caspica and M. rivulata, as our model. These taxa are estimated to have diverged some 5.3–7.0 million years ago. Using rangewide sampling and 13 unlinked polymorphic microsatellite markers, five nuclear loci and one mitochondrial gene, we show that hybridization is rare along the contact zone of the two species in Turkey. However, we discovered an unexpected hybrid swarm in the southern Levant that has been hitherto identified with M. rivulata. This hybrid swarm is separated from the inland species M. caspica by a 700‐km‐wide distribution gap corresponding to the Syrian Desert. Ecological palaeomodelling suggests that during more humid climatic episodes in the Last Glacial Maximum and mid‐Holocene, the current contact zone extended into the southern Levant, facilitating the establishment of the now isolated hybrid swarm. Our results support that there is not necessarily a general hybridization pattern in a given species couple and that the extent of gene flow may differ considerably in different parts of the distribution range. Moreover, our results highlight that studies on hybridization should not focus only on extant contact and hybrid zones, but should use rangewide sampling to detect signals of ancient hybridization that might otherwise be missed.