Data from: Phenotypic and genotypic variation across a stable white-eye (Zosterops sp.) hybrid zone in central South Africa

The interbreeding of two species after a period of separation (secondary contact) most often results in stable areas of hybridization or tension zones characterized by selection against hybrid individuals. Three plumage forms of Zosterops meet and interbreed in central South Africa. Here we examine how phenotypic measures (biometric and plumage) and genotypic markers (mitochondrial and nuclear DNA) change through a putative hybrid zone located in the area where the ranges of the Orange River white-eye Zosterops pallidus and a subspecies of the Cape white-eye Zosterops virens capensis meet. Four of the five sequenced loci (i.e. ATP6, MUSK, GADPH and TGF-β2) showed strong divergence and differentiation between allopatric parental populations, whereas the sex-linked CHD1Z locus exhibited high homogeneity. Microsatellite data also distinguished between pure Z. pallidus and Z. v. capensis populations. Together, the nuclear data (introns and microsatellites) identified at least 12 hybrid individuals as later generation hybrids (i.e. F2 or backcrosses), and no F1 hybrids were detected. As genetic incompatibility does not appear to play a role in restricting this stable hybrid zone, it is likely that environmental conditions including biome type and edge effect are constraining hybrid zone movement.两个物种在经历一段地理隔离时期后发生的种间杂交（即次生接触（secondary contact）），通常会形成稳定的杂交区域或杂交张力带，其典型特征为对杂交个体存在选择淘汰作用。在南非中部，绣眼鸟属（Zosterops）的三种羽型相遇并发生种间杂交。本研究聚焦于奥兰治河绣眼鸟（Zosterops pallidus）与海角绣眼鸟开普亚种（Zosterops virens capensis）的分布区交汇地带的疑似杂交带，旨在解析该区域内表型指标（形态测量与羽色特征）以及遗传标记（线粒体DNA与核DNA）的空间变化规律。本研究对5个测序基因座中的4个（即ATP6、MUSK、GADPH与TGF-β2）开展分析，结果显示异域亲本种群间存在显著的遗传分化与遗传结构差异；而性连锁基因座CHD1Z则表现出高度的遗传均一性。微卫星遗传标记数据同样可有效区分纯合的淡色绣眼鸟（Z. pallidus）与开普海角绣眼鸟（Z. v. capensis）种群。综合核基因组数据（内含子与微卫星标记）的分析结果，研究共鉴定出至少12只晚世代杂交个体（即F2代或回交个体），未检测到F1代杂交个体。鉴于遗传不相容性似乎并未参与限制该稳定杂交带的空间扩张，因此制约该杂交带移动的关键因素更可能为环境条件，包括生物群系类型与边缘效应。