Multilocus Analyses of Speciation, Hybridization, and Population Structure in Brood Parasitic Indigobirds

物种形成，即一个祖先种群产生两个具有不同特征的后代物种，是产生地球上生命多样性的基本进化过程之一。同域物种形成（即没有地理隔离）的可能性在进化理论家中引起了相当大的争议。这项研究将考察靛蓝鸟的进化史，这是一群非洲鸣禽，可能是脊椎动物中同域物种形成的最清晰的例子。作为寄主，靛蓝鸟只通过在其他物种的巢中产卵来繁殖，这为物种形成奠定了基础，因为从不同寄主物种那里学习的歌曲是靛蓝鸟选择配偶的主要标准。坦桑尼亚的实地工作将扩大对土著鸟类种群的地理抽样。此外，将使用基于聚结理论的新开发方法分析大量分子遗传标记。这些方法对于评估一种有趣的可能性是必要的，即罕见的杂交阻碍了大多数靛蓝基因组的分化，即使自然选择导致物种在控制宿主特异性适应的少数基因上出现分歧。这项研究将提高我们对物种形成、适应和种群遗传结构形成过程的理解，这些都是进化生物学的核心问题。这项工作还将为两名研究生提供培训机会，并将通过展示新的分析方法来推进分子生态学领域。最后，这项工作将继续提高靛蓝鸟的形象，其非凡的自然历史是教授进化生物学和培养公众对科学和生物多样性的兴趣的理想选择。

Speciation, in which one ancestral population gives rise to two descendant species with distinct characteristics, is one of the fundamental evolutionary processes generating the diversity of life on earth. The possibility of sympatric speciation (i.e., without geographic isolation) has generated considerable controversy among evolutionary theorists. This research will examine the evolutionary history of the indigobirds, a group of African songbirds that provides perhaps the clearest example of sympatric speciation in vertebrates. As brood parasites, indigobirds reproduce only by laying eggs in the nests of other species, which sets the stage for speciation because songs learned from different host species serve as the principal criterion in indigobird mate choice. Field work in Tanzania will extend the geographic sampling of indigobird populations. In addition, a large set of molecular genetic markers will be analyzed using newly developed methods based on coalescent theory. These approaches are necessary to evaluate the intriguing possibility that infrequent interbreeding retards differentiation across most of the indigobird genome, even as natural selection results in divergence of the species at a small number of genes controlling host-specific adaptations.The proposed research will improve our understanding of speciation, adaptation, and the processes shaping the genetic structure of populations, which are central questions in evolutionary biology. The work will also provide training opportunities for two graduate students and will advance the field of molecular ecology by demonstrating new methods of analysis. Finally, the work will continue to raise the profile of indigobirds, whose remarkable natural history is ideal for teaching evolutionary biology and fostering interest in science and biodiversity among the public.