Data from: Non-equilibrium conditions explain spatial variability in genetic structuring of little penguin (Eudyptula minor)

Factors responsible for spatial structuring of population genetic variation are varied, and in many instances there may be no obvious explanations for genetic structuring observed, or those invoked may reflect spurious correlations. A study of little penguins (Eudyptula minor) in southeast Australia documented low spatial structuring of genetic variation with the exception of colonies at the western limit of sampling, and this distinction was attributed to an intervening oceanographic feature (Bonney Upwelling), differences in breeding phenology, or sea level change. Here, we conducted sampling across the entire Australian range, employing additional markers (12 microsatellites and mitochondrial DNA, 697 individuals, 17 colonies). The zone of elevated genetic structuring previously observed actually represents the eastern half of a genetic cline, within which structuring exists over much shorter spatial scales than elsewhere. Colonies separated by as little as 27 km in the zone are genetically distinguishable, while outside the zone, homogeneity cannot be rejected at scales of up to 1400 km. Given a lack of additional physical or environmental barriers to gene flow, the zone of elevated genetic structuring may reflect secondary contact of lineages (with or without selection against interbreeding), or recent colonization and expansion from this region. This study highlights the importance of sampling scale to reveal the cause of genetic structuring.

驱动种群遗传变异空间结构形成的因素多种多样，在诸多案例中，观测到的遗传结构并无明确解释，抑或是所提出的假说仅反映了虚假相关。此前针对澳大利亚东南部小蓝企鹅（Eudyptula minor）的研究显示，除采样西限的繁殖群外，遗传变异的空间结构程度较低，该差异被归因于一处居间的海洋学特征——邦尼上升流（Bonney Upwelling）、繁殖物候差异或海平面变化。
本研究覆盖澳大利亚全境的分布范围开展采样，使用了新增的遗传标记：12个微卫星位点（microsatellites）与线粒体DNA（mitochondrial DNA），共计分析697只个体、17个繁殖群。
此前观测到的遗传结构增强区域，实际上是遗传渐变群（genetic cline）的东半部分；相较于其他区域，该区域内的遗传结构在更短的空间尺度上即可显现。在该区域内，繁殖群间距仅27公里即可通过遗传学手段区分；而在区域外，即便间距达1400公里，仍无法拒绝遗传同质性的假设。
鉴于基因流不存在额外的物理或环境阻隔，该遗传结构增强区域可能反映了不同谱系的二次接触（secondary contact，存在或不存在针对种间杂交的选择），或是该区域近期发生了种群定居与扩张。
本研究凸显了采样尺度在解析遗传结构成因中的重要性。