Feldman Chris R, Spicer Greg S
Department of Biology, Utah State University, Logan, Utah 84322-5305, USA.
Mol Ecol. 2006 Jul;15(8):2201-22. doi: 10.1111/j.1365-294X.2006.02930.x.
The ultimate goal of comparative phylogeographical analyses is to infer processes of diversification from contemporary geographical patterns of genetic diversity. When such studies are employed across diverse groups in an array of communities, it may be difficult to discover common evolutionary and ecological processes associated with diversification. In order to identify taxa that have responded in a similar fashion to historical events, we conducted comparative phylogeographical analyses on a phylogenetically and ecologically limited set of taxa. Here, we focus on a group of squamate reptiles (snakes and lizards) that share similar ecological requirements and generally occupy the same communities in the western USA. At a gross level, deep genetic division in Contia tenuis, Diadophis punctatus, Elgaria multicarinata, the Charina bottae complex, and Lampropeltis zonata are often concordant in the Transverse Ranges, the Monterey Bay and Sacramento-San Joaquin Delta region, and the southern Sierra Nevada in California. Molecular clock estimates suggest that major phyletic breaks within many of these taxa roughly coincide temporally, and may correspond to important geological events. Furthermore, significant congruence between the phylogeographies of E. multicarinata and L. zonata suggests that the succession of vicariance and dispersal events in these species progressed in concert. Such congruence suggests that E. multicarinata and L. zonata have occupied the same communities through time. However, across our entire multi-taxon data set, the sequence of branching events rarely match between sympatric taxa, indicating the importance of subtle differences in life history features as well as random processes in creating unique genetic patterns. Lastly, coalescent and noncoalescent estimates of population expansion suggest that populations in the more southerly distributed clades of C. tenuis, D. punctatus, E. multicarinata, and L. zonata have been stable, while populations in more northerly clades appear to have recently expanded. This concerted demographic response is consistent with palaeontological data and previous phylogeographical work that suggests that woodland habitat has become more restricted in southern California, but more widespread in the North during Holocene warming. Future phylogeographical work focusing on allied and ecologically associated taxa may add insight into the ecological and evolutionary processes that yield current patterns of genetic diversity.
比较系统地理学分析的最终目标是从当代遗传多样性的地理格局中推断物种分化过程。当在一系列群落中的不同类群上进行此类研究时，可能难以发现与物种分化相关的共同进化和生态过程。为了识别对历史事件有相似反应的分类群，我们对一组在系统发育和生态上受限的分类群进行了比较系统地理学分析。在这里，我们关注一组有鳞目爬行动物（蛇和蜥蜴），它们具有相似的生态需求，并且在美国西部通常占据相同的群落。从总体水平来看，细纹康蛇、花斑锦蛇、多嵴柔蜥、博氏沙蟒复合体和宽带王蛇的深度遗传分化在加利福尼亚州的横向山脉、蒙特雷湾和萨克拉门托 - 圣华金河三角洲地区以及内华达山脉南部通常是一致的。分子钟估计表明，这些分类群中许多的主要谱系分支在时间上大致重合，并且可能与重要的地质事件相对应。此外，多嵴柔蜥和宽带王蛇的系统地理学之间的显著一致性表明，这些物种中隔离和扩散事件的相继发生是协同进行的。这种一致性表明，多嵴柔蜥和宽带王蛇长期以来一直占据相同的群落。然而，在我们整个多分类群数据集中，同域分布的分类群之间分支事件的顺序很少匹配，这表明生活史特征的细微差异以及随机过程在形成独特遗传模式方面的重要性。最后，种群扩张的合并估计和非合并估计表明，细纹康蛇、花斑锦蛇、多嵴柔蜥和宽带王蛇分布更靠南的分支中的种群一直稳定，而分布更靠北的分支中的种群似乎最近有所扩张。这种一致的种群动态反应与古生物学数据以及先前的系统地理学研究结果一致，这些研究表明，在全新世变暖期间，加利福尼亚州南部的林地栖息地变得更加受限，但在北部更为广泛。未来专注于相关和生态关联分类群的系统地理学研究可能会深入了解产生当前遗传多样性模式的生态和进化过程。
