Department of Biology, University of Central Florida, Orlando, FL 32816, USA.
Mol Phylogenet Evol. 2009 Dec;53(3):653-67. doi: 10.1016/j.ympev.2009.07.022. Epub 2009 Jul 28.
Lineage diversification in the Neotropics is an interesting topic in evolutionary biology but is also one of the least understood. The abiotic and biotic complexity of the region precludes generalizations that can be drawn regarding the historical evolutionary processes responsible for the diversity observed. The snake genus Leptodeira provides an excellent opportunity to investigate such processes because it spans the entire Neotropical region. In this study, we infer the phylogenetic position of Leptodeira within Dipsadinae, estimate evolutionary relationships among and within Leptodeira species, and estimate the diversification time and biogeography of the genus. Three mitochondrial gene regions were sequenced for individuals representing all the Leptodeira species and most subspecies currently recognized. Additionally, two nuclear protein-coding gene regions were sequenced for representatives of each species and several genera within the Dipsadinae. We infer that several Leptodeira species are either paraphyletic or polyphyletic as currently recognized, and that most recognized subspecies are not monophyletic lineages. Despite the taxonomic discordance with evolutionary relationships, clades appear to correspond very well to major biogeographic regions of Mexico, Central America and South America. Our results thus highlight the important role of the Miocene and Pliocene for lineage diversification in the Neotropics. Additionally, our time estimates suggest that recent intraspecific phylogeographic structure is likely the result of habitat and climatic fluctuations during the Pleistocene. Cumulatively, our inferences of lineage diversification within Leptodeira suggest a complex evolutionary scenario in the Mexican transition zone and a north to south expansion with a final colonization of the tropics in South America.
在进化生物学中，新热带地区的谱系多样化是一个有趣的话题，但也是了解最少的话题之一。该地区的非生物和生物复杂性排除了可以针对导致观察到的多样性的历史进化过程进行概括的可能性。蛇属 Leptodeira 为研究这些过程提供了绝佳的机会，因为它跨越了整个新热带地区。在这项研究中，我们推断了 Leptodeira 在 Dipsadinae 中的系统发育位置，估计了 Leptodeira 物种之间和内部的进化关系，并估计了该属的多样化时间和生物地理学。我们对代表所有 Leptodeira 物种和目前大多数亚种的个体进行了三个线粒体基因区域的测序。此外，我们还对 Dipsadinae 中的每个物种和几个属的代表进行了两个核蛋白编码基因区域的测序。我们推断，目前被认为是几个 Leptodeira 物种的种是并系或多系的，并且大多数被认可的亚种不是单系谱系。尽管与进化关系存在分类学上的不一致，但支系似乎与墨西哥、中美洲和南美洲的主要生物地理区域非常吻合。因此，我们的研究结果强调了中新世和上新世对新热带地区谱系多样化的重要作用。此外，我们的时间估计表明，最近的种内系统地理结构很可能是更新世期间栖息地和气候波动的结果。总的来说，我们对 Leptodeira 内谱系多样化的推断表明，在墨西哥过渡带存在复杂的进化情景，以及从北向南的扩张，最终在南美洲热带地区的殖民化。
