Dissertation Research: Molecular Systematics of Xenarthrans

9423665阿什利拟议的研究涉及对哺乳动物文冠目(树懒、螳螂和食蚁兽)及其近亲穿山甲(穿山甲或有鳞食蚁兽)的分子系统研究。这些分类群之间的关系以及与其他哺乳动物目之间的关系仍然存在争议。建立或驳斥Xenarthra作为哺乳动物基本谱系的地位，对于解释哺乳动物进化的整体模式至关重要。%此外，这些数据还将提供有关该种群从南美洲起源到中美洲和安的列斯群岛的生物地理历史的重要信息。如果Xenartrans与穿山甲密切相关，而穿山甲已知于非洲、亚洲和欧洲，可能还有北美，这就提出了一个可验证的假说，即这些类群的分化可能发生在8500万年前非洲和南美洲分离之前。这将大大推迟真兽类的辐射时间。***

9423665 Ashley The proposed research involves a molecular systematic study of the mammalian order Xenarthra (sloths, armadillos, and anteaters) and their close relatives the Pholidota (pangolins or scaly anteaters). The relationships among these taxa and with other mammalian orders remain controversial. Establishing or refuting the position of the Xenarthra as a basal lineage of mammals is critical for interpreting the overall pattern of mammalian evolution. %%% In addition the data will provide important information on the biogeographic history of the group from its South American origin and dispersal to Central American and the Antilles. If xenarthrans are closely related to pangolins which are known from Africa, Asia and Europe and possibly North America it suggests a testable hypothesis, divergence of these groups that would have predated the separation of Africa and South America which occurred 85 million years ago. This would push back considerably the timing of the radiation of eutherian mammals. ***