Ice sheets promote speciation in boreal birds
Ice sheets promote speciation in boreal birds
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DOI：
10.1098/rspb.2004.2803
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发表时间：
2004-09-22
影响因子：
4.7
通讯作者：
Schluter, D
中科院分区：
文献类型：
--
作者：
Weir, JT;Schluter, D
遗传数据表明，地球上大多数最年轻的陆生物种在大冰川推进之前很久就已经结合在一起了，这一假设对更新世冰期在产生当今物种多样性方面发挥了重要作用的假设提出了挑战。然而，研究一直偏向于分布在低纬度地区的动物，这些动物没有被推进的冰盖直接破碎。利用线粒体序列分化和分子钟，我们比较了高纬度北方森林中属于超物种复合体的鸟类物种对与亚寒带和热带新大陆鸟类物种对的合并时间。值得注意的是，所有北方超物种的合并事件都可以追溯到更新世，这为物种形成通常在最近的冰期开始提供了直接证据。北方超级物种的特有模式似乎将分化的时间与更新世中期和晚更新世期间冰盖对北方森林的破坏联系起来。与北方超级物种相比，更新世期间只有56%的亚北方超级物种和46%的热带超级物种合并在一起，这表明直接被冰盖破碎的鸟类动物经历了快速的多样化，而那些分布在更南方的鸟类受到的影响较小。对于更新世前北方鸟类中没有超级物种的一种解释是，北方避难所中存在强大的选择压力，导致超级物种成员以加速的速度实现生态分化。
The premise that Pleistocene ice ages played an important role in generating present-day species diversity has been challenged by genetic data indicating that most of the youngest terrestrial species on Earth coalesced long before major glacial advances. However, study has been biased towards faunas distributed at low latitudes that were not directly fragmented by advancing ice sheets. Using mitochondrial sequence divergence and a molecular clock, we compared the coalescence times of pairs of avian species belonging to superspecies complexes from the high-latitude boreal forest with those of sub-boreal and tropical avifaunas of the New World. Remarkably, all coalescence events in boreal superspecies date to the Pleistocene, providing direct evidence that speciation was commonly initiated during recent glacial periods. A pattern of endemism in boreal superspecies plausibly links the timing of divergence to the fragmentation of the boreal forest by ice sheets during the Mid- and Late Pleistocene. In contrast to the boreal superspecies, only 56% of sub-boreal and 46% of tropical superspecies members coalesced during the Pleistocene, suggesting that avifaunas directly fragmented by ice sheets experienced rapid rates of diversification, whereas those distributed farther south were affected to a lesser extent. One explanation for the absence of pre-Pleistocene superspecies in boreal avifaunas is that strong selection pressures operated in boreal refugia, causing superspecies members to achieve ecological differentiation at an accelerated rate.