Extensive hybridization between two Andean warbler species with shallow divergence in mtDNA

Studying processes acting on differentiated populations upon secondary contact, such as hybridization, is important to comprehensively understand how species are formed and maintained over time. However, avian speciation studies in the tropical Andes have largely focused on the role of topographic and ecological barriers promoting divergence in allopatry, seldom examining hybridization and introgression. We describe a hybrid zone involving 2 closely related Andean warblers (Parulidae), the Golden-fronted Redstart (Myioborus ornatus) and the Spectacled Redstart (Myioborus melanocephalus). Geographic ranges of these species abut near the Colombia-Ecuador border and many specimens from the region exhibit intermediate phenotypes, but a formal description of phenotypic variation in the contact zone were heretofore lacking. We collected specimens across a transect encompassing the area where ranges abut and areas where only “pure” parental phenotypes of M. ornatus chrysops and M. melanocephal...

研究次级接触后分化种群所经历的演化过程（如杂交事件），对于全面理解物种随时间的形成与维持机制具有重要意义。然而，热带安第斯山脉地区的鸟类物种形成研究，大多聚焦于促进异域分化的地形与生态屏障的作用，极少关注杂交与基因渐渗过程。本研究描述了一个涉及两种近缘安第斯森莺（森莺科Parulidae）的杂交带：金顶红尾森莺（Myioborus ornatus）与眼斑红尾森莺（Myioborus melanocephalus）。这两个物种的分布范围在哥伦比亚与厄瓜多尔边境附近毗邻，该区域的诸多标本呈现中间表型，但迄今为止尚未有针对该接触带表型变异的正式描述。我们横跨一条样带采集了标本，该样带覆盖了物种分布毗邻区域，以及仅存在M. ornatus chrysops与M. melanocephalus‘纯种’亲本表型的区域……