Data from: Population signatures of large-scale, long-term disjunction and small-scale, short-term habitat fragmentation in an Afromontane forest bird

The Eastern Afromontane cloud forests occur as geographically distinct mountain exclaves. The conditions of these forests range from large to small, and from fairly intact to strongly degraded. For this study we sampled individuals of the forest bird species, the Montane White-eye Zosterops poliogaster from 16 sites and four mountain archipelagos. We analysed 12 polymorphic microsatellites and three phenotypic traits, and calculated Species Distribution Models (SDMs) to project past distributions and predict potential future range shifts under a scenario of climate warming. We found well supported genetic and morphologic clusters that corresponded to the mountain ranges where populations were sampled, with 43% of all alleles being restricted to single mountains. Genetic population differentiation strongly matched each other at a regional level. Our data suggest that large-scale and long-term geographic isolation on mountain islands caused genetically and morphologically distinct populations clusters in Z. poliogaster. However, major genetic and biometric splits were not correlated to the geographic distances among populations. This heterogeneous pattern can be explained by past climatic shifts, as highlighted by our SDM-projections. Anthropogenically fragmented populations showed lower genetic diversity and a lower mean body mass, possibly in response to suboptimal habitat conditions. Based on these findings and the results from our SDM analysis, we predict further losses of genotypic and phenotypic uniqueness in the wake of climate change, due to the contraction of the species´ climatic niche and subsequent decline in population size.

东非山地云雾林以地理上独立的山地飞地形式存在。这类森林的生境条件跨度不一，从大面积完整原生林到严重退化的生境均有分布。本研究从4个山地群岛的16个采样点中，采集了森林鸟类物种山地绣眼鸟（Montane White-eye，学名Zosterops poliogaster）的个体样本。我们对12个多态性微卫星（microsatellites）位点与3个表型性状开展了分析，并构建了物种分布模型（Species Distribution Models, SDMs），以推演该物种的历史分布，并预测气候变暖情景下其潜在的未来分布范围变化。研究发现了与采样种群所在山地范围对应的、得到充分支持的遗传与形态学聚类结果，且所有等位基因中有43%仅局限于单个山地。遗传种群分化格局在区域尺度上呈现极强的一致性。我们的数据表明，山地岛屿上长期且大规模的地理隔离，使得山地绣眼鸟形成了遗传与形态上均存在显著差异的种群聚类。然而，主要的遗传与生物形态测量分化并未与种群间的地理距离呈现显著相关。我们的SDM推演结果证实，这一异质性格局可由过往的气候变迁得到合理解释。受人为活动干扰的破碎化种群展现出更低的遗传多样性与平均体重，这可能是对不适宜生境条件的响应。基于上述发现与SDM分析结果，我们预测：随着该物种气候生态位的收缩以及种群规模的后续下降，气候变化将进一步导致其基因型与表型独特性的丧失。