New dates and new rates for divergence across the Isthmus of Panama
New dates and new rates for divergence across the Isthmus of Panama
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DOI：
10.1098/rspb.1998.0568
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发表时间：
1998-12-07
影响因子：
4.7
通讯作者：
Weigt, LA
中科院分区：
文献类型：
--
作者：
Knowlton, N;Weigt, LA
由巴拿马地峡分隔开的姐妹物种已被广泛用于估计分子进化速率。这些估计基于这样的假设：大约三百万年前，加勒比海和东太平洋之间的联系关闭时，大多数类群几乎同时发生了地理隔离。在这里，我们表明，这种假设对于已经分析了许多分类单元和多个遗传标记的唯一属是无效的。 Alpheus 属 15 对鳄虾的等位酶和线粒体 COI 基因表现出的分化模式高度一致，表明它们为估计自基因流停止以来的时间提供了合理的基础。姐妹物种对之间的遗传分化程度相差四倍以上。来自红树林环境的姐妹物种表现出最小的差异，如果这些是最后被划分的栖息地的话，这是可以预料的。使用该对产生每百万年 1.4% 的序列分歧率，隐含 3-1800 万年前 15 对的分离时间。过去的许多研究可能高估了分子进化的速度，因为他们对在地峡最终闭合之前就已经分开的分子对进行了采样。
Sister species separated by the Isthmus of Panama have been widely used to estimate rates of molecular evolution. These estimates are based on the assumption that geographic isolation occurred nearly simultaneously for most taxa, when connections between the Caribbean and eastern Pacific closed approximately three million years ago. Here we show that this assumption is invalid for the only genus for which many taxa and multiple genetic markers have been analysed. Patterns of divergence exhibited by allozymes and the mitochondrial COI gene are highly concordant for 15 pairs of snapping shrimp in the genus Alpheus, indicating that they provide a reasonable basis for estimating time since cessation of gene flow The extent of genetic divergence between pairs of sister species varied over fourfold. Sister species from mangrove environments showed the least divergence, as would be expected if these were among the last habitats to be divided. Using this pair yields a rate of sequence divergence of 1.4% per one million years, with implied times of separation for the 15 pairs of 3-18 million years ago. Many past studies may have overestimated rates of molecular evolution because they sampled pairs that were separated well before final closure of the Isthmus.