Niche divergence promotes rapid diversification of East African sky island white-eyes (Aves: Zosteropidae)

The Eastern Afromontane biodiversity hotspot composed of highly fragmented forested highlands (sky islands) harbours exceptional diversity and endemicity, particularly within birds. To explain their elevated diversity within this region, models founded on niche conservatism have been offered, although detailed phylogeographic studies are limited to a few avian lineages. Here we focus on the recent songbird genus Zosterops, represented by montane and lowland members, to test the roles of niche conservatism versus niche divergence in the diversification and colonization of East Africa’s sky islands. The species-rich white-eyes are a typically homogeneous family with an exceptional colonizing ability, but in contrast to their diversity on oceanic islands, continental diversity is considered depauperate and has been largely neglected. Molecular phylogenetic analysis reveals extensive polyphyly among different montane populations of Z. poliogastrus with these larger and heavier endemic popul...东非山地生物多样性热点地区由高度破碎化的森林高地（天空岛，sky islands）组成，拥有极高的物种多样性与特有性，尤以鸟类类群最为突出。为解释该区域内鸟类多样性的异常升高，学界已提出基于生态位保守性（niche conservatism）的相关模型，但针对该主题的详细系统地理学研究目前仅局限于少数鸟类支系。本研究聚焦于以山地与低地类群为代表的鸣禽属——绣眼鸟属（Zosterops），以此检验生态位保守性与生态位分化（niche divergence）在东非天空岛的物种分化与定居扩散过程中所发挥的作用。物种丰富的绣眼鸟科通常具有较高的形态同质性，且拥有极强的扩散定居能力；但与海洋岛屿上的物种多样性格局形成鲜明对比的是，大陆分布的绣眼鸟类群多样性被认为较为贫乏，且长期以来未得到足够关注。分子系统发育分析结果显示，灰腹绣眼鸟（Zosterops poliogastrus）的不同山地种群间存在广泛的多系现象，而这些体型更大、体重更重的特有种群……