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.两个物种经历一段时期的地理隔离后发生再交配（即二次接触（secondary contact）），其结果通常会形成稳定的杂交区域或张力区，此类区域的典型特征为对杂交个体存在选择淘汰作用。三种绣眼鸟属（Zosterops）羽型在南非中部相遇并发生杂交。本研究针对奥兰治河绣眼鸟（Zosterops pallidus）与开普绣眼鸟开普亚种（Zosterops virens capensis）分布区交汇的推测杂交带，分析其中的表型指标（形态测量与羽色特征）以及遗传标记（线粒体DNA与核DNA）的变化规律。 本次研究对5个测序基因座中的4个（即ATP6、MUSK、GADPH及TGF-β2）进行分析，结果显示异域亲本种群间存在显著的遗传分化；而性连锁CHD1Z基因座则表现出高度的遗传均一性。微卫星数据同样可有效区分纯合的淡色绣眼鸟（Z. pallidus）与开普绣眼鸟开普亚种（Z. v. capensis）种群。结合核数据（内含子与微卫星）的分析结果，本研究共鉴定出至少12只后代杂交个体（即F2代或回交个体），未检测到F1杂交个体。鉴于遗传不相容性并未对该稳定杂交带的维持发挥作用，推测包括生物群系类型与边缘效应在内的环境条件，才是制约该杂交带扩散的关键因素。