Brumfield Robb T, Edwards Scott V
Museum of Natural Science, 119 Foster Hall, Louisiana State University, Baton Rouge, Louisiana 70803, USA.
Evolution. 2007 Feb;61(2):346-67. doi: 10.1111/j.1558-5646.2007.00039.x.
The Andean uplift played important roles in the historical diversification of Neotropical organisms, both by producing new high-elevation habitats that could be colonized and by isolating organisms on either side of the mountains. Here, we present a molecular phylogeny of Thamnophlius antshrikes, a clade of 30 species whose collective distribution spans nearly the entirety of lowland habitats in tropical South America, the eastern slope foothills of the Andes, and the tepuis of northern South America. Our goal was to examine the role of the Andes in the diversification of lowland and foothill species. Using parsimony and Bayesian ancestral state reconstructions of a three-state distribution character (lowland-restricted, lowland-to-highland, highland-restricted), we found that the Andes were colonized twice independently and the tepuis once from lowland-restricted ancestors. Over the entire evolutionary history of Thamnophilus, the highest transition rates were between highland-restricted and lowland-to-highland distributions, with extremely low rates into and out of lowland-restricted distributions. This pattern suggests lowland-restricted distributions are limited not by physiological constraints, but by other forces, such as competition. These results highlight the need for additional comparative studies in elucidating processes associated with the colonization of high-elevation habitats and the differentiation of populations within them.
安第斯山脉的隆升在新热带生物的历史多样化过程中发挥了重要作用，这既体现在产生了可供生物栖息的新的高海拔栖息地，也体现在将山脉两侧的生物隔离开来。在此，我们展示了薮蚁鵙属的分子系统发育情况，该属包含30个物种，其分布范围几乎涵盖了南美洲热带地区的全部低地栖息地、安第斯山脉东坡山麓以及南美洲北部的桌状山。我们的目标是研究安第斯山脉在低地和山麓物种多样化过程中的作用。通过使用简约法和贝叶斯祖先状态重建方法，对一个三态分布特征（低地限制分布、低地到高地分布、高地限制分布）进行分析，我们发现安第斯山脉被两次独立殖民，桌状山则是从低地限制分布的祖先那里被殖民了一次。在薮蚁鵙属的整个进化历史中，最高的转变率发生在高地限制分布和低地到高地分布之间，而进入和离开低地限制分布的速率极低。这种模式表明，低地限制分布并非受生理限制，而是受其他因素限制，比如竞争。这些结果凸显了在阐明与高海拔栖息地殖民化以及其中种群分化相关过程方面进行更多比较研究的必要性。
