Speciation in Brood Parasitic Indigobirds

非洲青鸟(Vidua属)是专性繁殖寄生虫，只有在其他物种的巢中产卵才能繁殖。青鸟是高度特定于宿主的，幼虫精确地模仿它们各自宿主幼虫的嘴部颜色和图案。成年后，雄性蓝知更鸟会模仿主人的歌声。这种行为导致了青鸟物种的遗传凝聚力，因为雌性也会在宿主物种上留下印记，并根据歌声选择配偶。然而，这些相同的行为机制可能会导致新寄主物种定居后的生殖隔离和快速物种形成。这项研究将使用分子遗传标记来研究板蓝鸟物种和种群的进化史和遗传结构，使用在非洲各地收集的500多种板蓝鸟的样本。此外，在喀麦隆的一项深入的实地研究将直接评估使用不同宿主的青鸟种群之间正在进行的杂交和遗传导入的发生率。青鸟系统是快速进化多样化和适应性进化的显著例子，代表了可以在进化过程中研究的不寻常情况之一。这项研究将有助于进化生物学家对物种形成的机制以及自然选择和性选择在生物多样性产生中的作用重新产生兴趣。对青鸟种群进化史和遗传结构的清楚了解也将为未来分析嘴部模仿的遗传和发育机制奠定基础，嘴部模仿是这些宿主特有的幼虫的关键遗传适应。

Sorenson0089757The African indigobirds (genus Vidua) are obligate brood parasites, reproducing only by laying their eggs in the nests of other species. Indigobirds are highly host-specific and the young parasites precisely mimic the mouth colors and patterns in the young of their respective hosts. As adults, male indigobirds mimic the songs of their hosts. This behavior results in the genetic cohesion of indigobird species because females also imprint on the host species and choose their mates based on song. These same behavioral mechanisms, however, may result in reproductive isolation and rapid speciation after the colonization of a new host species. This research will use molecular genetic markers to investigate the evolutionary history and genetic structure of indigobird species and populations using samples from over 500 indigobirds collected throughout Africa. In addition, an intensive field study in Cameroon will directly evaluate the incidence of ongoing hybridization and genetic introgression among indigobird populations using different hosts.The indigobird system is a remarkable example of rapid evolutionary diversification and adaptive evolution and represents one of those unusual situations in which the evolutionary process can be studied in progress. This research will contribute to a renewed interest among evolutionary biologists in the mechanisms of speciation and the roles of natural and sexual selection in generating biodiversity. A clear understanding of the evolutionary history and genetic structure of indigobird populations will also lay the groundwork for future analyses of the genetic and developmental mechanisms underlying mouth mimicry, the key genetic adaptation of these host-specific brood parasites.