Mesozoic continental fragmentations and lizard radiations

已从代表鳞目主要家族的各种蜥蜴物种中确定了完整或接近完整的线粒体DNA序列。结合以前发表的其他脊椎动物的有丝分裂基因组序列，我们进行了分子系统发育分析。通过最大似然法建立了可靠的系统发育关系，并使用贝叶斯方法估计了分歧时间，而不假设分子时钟。根据这些分子结果和独立的地质和古生物数据对生物地理学假说进行了评估，我们的主要发现如下。1)主要蜥蜴科之间的分化早于白垩纪的大规模大陆碎裂，但AGamidae和Chamaeleonidae之间的分化可能发生在白垩纪中期。2)另一方面，蛇类的家系辐射大多发生在白垩纪/第三系界线之后。3)盘古猿分裂为劳拉西亚和冈瓦瓦兰岛可能与蜥蜴的一些较浅的分化有关，例如，真蜥亚科和壁虎亚科之间的分化。其他发现包括首次描述了龙血亚科龙血竭线粒体基因组中的tRNA基因反转的特征。

Complete or nearly complete mitochondrial DNA sequences have been determined from various species of lizards that represent major families of the order Squamata. Together with previously published mitogenomic sequences of other vertebrate taxa, we have conducted molecular phylogenetic analyses. Reliable phylogenetic relationships have been established by the maximum-likelihood method and divergence times were estimated using a Baysian method without assuming the molecular clock. Biogeographic hypotheses were evaluated in light of these molecular results and independent geological and paleontological data Our major findings are the following. 1) Divergences between major lizard families predate the large-scale continental fragmentation during Cretaceous time, except for the divergence between Agamidae and Chamaeleonidae that likely occurred in the mid-Cretaceous. 2) On the other hand, most familial radiations of snakes postdate the Cretaceous/Tertiary boundary. 3) The break-up of Pangea into Laurasia and Gondwanaland may have been correlated with some shallower divergences of lizards, e.g., between Eublepharinae and Gekkoninae. Other findings include the first characterization of gene inversion in vertebrate mitochondrial geneomes in the proline tRNA gene of Draconinae agamids.