PDF(Pubmed)
Abstract：
Secondary contact between previously allopatric lineages offers a test of reproductive isolating mechanisms that may have accrued in isolation. Such instances of contact can produce stable hybrid zones-where reproductive isolation can further develop via reinforcement or phenotypic displacement-or result in the lineages merging. Ongoing secondary contact is most visible in continental systems, where steady input from parental taxa can occur readily. In oceanic island systems, however, secondary contact between closely related species of birds is relatively rare. When observed on sufficiently small islands, relative to population size, secondary contact likely represents a recent phenomenon. Here, we examine the dynamics of a group of birds whose apparent widespread hybridization influenced Ernst Mayr\'s foundational work on allopatric speciation: the whistlers of Fiji (Aves: Pachycephala). We demonstrate two clear instances of secondary contact within the Fijian archipelago, one resulting in a hybrid zone on a larger island, and the other resulting in a wholly admixed population on a smaller, adjacent island. We leveraged low genome-wide divergence in the hybrid zone to pinpoint a single genomic region associated with observed phenotypic differences. We use genomic data to present a new hypothesis that emphasizes rapid plumage evolution and post-divergence gene flow.
摘要：
先前的异族谱系之间的二次接触提供了对可能孤立产生的生殖隔离机制的测试。这种接触的情况可以产生稳定的杂化区-生殖隔离可以通过增强或表型置换进一步发展-或导致谱系合并。持续的二次接触在大陆系统中最为明显，其中来自亲本分类群的稳定输入可以很容易地发生。在海洋岛屿系统中，然而,与鸟类密切相关的物种之间的二次接触相对较少。当在足够小的岛屿上观察时，相对于人口规模，二次接触可能代表了最近的现象。这里,我们研究了一组鸟类的动力学，这些鸟类的明显广泛杂交影响了ErnstMayr关于异域物种形成的基础工作：斐济的哨子（Aves：Pachycephala）。我们展示了斐济群岛内部二次接触的两个明显实例，在一个更大的岛上形成了一个混合带，另一个导致一个完全混合的人口在一个较小的，邻近的岛屿。我们利用杂交区的低全基因组差异来确定与观察到的表型差异相关的单个基因组区域。我们使用基因组数据提出了一个新的假设，该假设强调了快速的羽毛进化和发散后的基因流。
