Molekulare Phylogenie und Biogeographie der Chamäleons

变色龙是一群蜥蜴，具有各种独特而壮观的形态特征。它们也是解释生物地理学问题的合适模型，例如印度洋陆地生物群起源中散布或变异的相对重要性。由于变色龙的低灵敏性，它们也可以在小范围内分析生物地理模式和过程。对于这样的分析，一个很好的解决和分类群丰富的系统发育假说是一个基本的要求。然而，目前已发表的对这些生物的系统发育研究存在分辨率低，特别是在基枝上，以及分类单元覆盖不完整的问题。本项目将基于多个核和线粒体基因的DNA序列，对变色龙进行多位点分子系统发育分析，并对至少80%的变色龙物种进行密集的分类群采样。获得的系统发育将使用贝叶斯分子钟方法进行日期测定，并将用于测试竞争的生物地理情景。结合现有的变色龙分布地理参考数据库，确定变色龙物种丰富度、特有性和系统发育多样性的地理热点。这些模式将用于重建变色龙的历史多样化过程，并推断自然保护的地理优先级。

Chameleons are a group of lizards characterized by various unique and spectacular morphological features. They also are an appropriate model with which to decipher biogeographic questions such as the relative importance of dispersal or vicariance in the origin of the biota on landmasses in the Indian Ocean. Due to their presumed (and partly demonstrated) low vagility, chameleons can also serve to analyse biogeographic patterns and processes on small scales. For such analyses, a wellresolved and taxon-rich phylogenetic hypothesis is a basic requirement. Yet, so far the published phylogenetic studies for these organisms suffer from low resolution, especially among basal branches, and from incomplete taxon coverage. The project proposed here will carry out a multilocus molecular phylogenetic analysis of chameleons, based on DNA sequences from multiple nuclear and mitochondrial genes, with a dense taxon sampling of at least 80% of all chameleon species. The phylogeny obtained will be dated using Bayesian molecular clock methods and will be used to test competing biogeographic scenarios. In concert with available georeferenced databases of chameleon distribution, we will identify geographic hotspots of chameleon species richness, endemism, and phylogenetic diversity. These patterns will be used to reconstruct historical diversification processes of chameleons, and to infer geographic priorities for nature conservation.