Historical Biogeography and the Evolution of Migration in Widely Distributed Avian Genera

9903544旅行者这项研究介绍了四个鸣禽属鸟类的历史生物地理和迁徙进化，每个鸟类属分布在一个以上的大陆。每个属的物种之间的关系将使用线粒体DNA序列来确定，结果将以两种方式使用。首先，当姐妹物种被确定为以类似时钟的方式从共同祖先进化而来时，分歧日期将应用于祖先节点。利用这些数据，将分析每一组的生物地理历史，以确定扩散和替代在大陆间和大陆内鸟类群发展中的相对作用。通过认识到进化和扩散都是公认的自然过程，并试图将物种分化时间与进化和扩散事件联系起来，将产生更严格的生物地理学假说。这反过来又增加了在每个组内确定特定隔离机制的可能性，从而增加了我们确定组之间的共享分布模式是否确实是共享历史的结果的能力。其次，物种特定的迁徙行为将被绘制到每个种群的系统发育图上；这种绘制方法将为每个属内迁徙的发展提供有趣的见解。此外，这种作图方法将产生关于鸟类迁徙进化的三个明确假设中的一些、全部或全部是否与几个洲际分布的种群中每一个迁徙的进化一致的见解。

9903544 VoelkerThis study addresses the historical biogeography and evolution of migration in four avian songbird genera, each of which is distributed on more than one continent. Relationships among the species in each genus will be determined using mitochondrial DNA sequences, and the results will be used in two ways. First, divergence dates will be applied to the ancestral nodes, when sister-species are determined to have evolved from a common ancestor in a clock-like manner. Using these dates, the biogeographic history of each group will be analyzed to determine the relative roles of dispersal and vicariance in the development of inter-and intracontinental avifaunas. By recognizing that both vicariance and dispersal are well established natural processes, and by attempting to correlate species divergence times with vicariant and dispersal events, more rigorous biogeographic hypotheses will result. This will in turn increase the likelihood that specific isolating mechanisms can be identified within each group, thus increasing our ability to determine whether shared distribution patterns between groups are indeed the result of shared histories. Second, species-specific migratory behaviors will be mapped onto the phylogeny of each group; this mapping method will provide interesting insights into the development of migration within each genus. In addition, this mapping method will generate insights into whether some, all or none of three explicit hypotheses concerning the evolution of avian migration are consistent with the evolution of migration in each of several intercontinentally distributed groups.