Data from: Extremely reduced dispersal and gene flow in an island bird

The Réunion grey white-eye, Zosterops borbonicus, a passerine bird endemic to Réunion Island in the Mascarene archipelago, represents an extreme case of microgeographical plumage colour variation in birds, with four distinct colour forms occupying different parts of this small island (2512 km2). To understand whether such population differentiation may reflect low levels of dispersal and gene flow at a very small spatial scale, we examined population structure and gene flow by analysing variation at 11 microsatellite loci among four geographically close localities (<26 km apart) sampled within the distribution range of one of the colour forms, the brown-headed brown form. Our results revealed levels of genetic differentiation that are exceptionally high for birds at such a small spatial scale. This strong population structure appears to reflect low levels of historical and contemporary gene flow among populations, unless very close geographically (<10 km). Thus, we suggest that the Réunion grey white-eye shows an extremely reduced propensity to disperse, which is likely to be related to behavioural processes.留尼汪灰绣眼鸟（Réunion grey white-eye, Zosterops borbonicus）是马斯卡林群岛留尼汪岛特有的雀形目鸟类，其为鸟类微地理羽色变异的极端案例：这座面积仅2512平方千米的小岛分布有四种截然不同的羽色型，各自占据不同区域。为探究此类种群分化是否反映了极小空间尺度下的低扩散水平与基因流情况，我们针对其中一种羽色型——褐头褐羽型的分布范围内的四个地理间距小于26千米的采样点位，通过分析11个微卫星位点（microsatellite loci）的遗传变异，对其种群结构与基因流展开了研究。研究结果显示，在如此狭小的空间尺度下，该鸟类的遗传分化水平在鸟类类群中极为显著。这种强烈的种群结构似乎反映了种群间极低的历史与当代基因流水平，仅地理距离极近（<10千米）的种群例外。据此我们推测，留尼汪灰绣眼鸟的扩散倾向极低，这一特征大概率与其行为学过程相关。