CNRS, UMR 7144, Team Div & Co, Lab. Adaptation et Diversité en Milieu Marin, Station Biologique de Roscoff, Roscoff, France.
Evolution. 2013 Jun;67(6):1660-75. doi: 10.1111/j.1558-5646.2012.01826.x.
Chaotic genetic patchiness denotes unexpected patterns of genetic differentiation that are observed at a fine scale and are not stable in time. These patterns have been described in marine species with free-living larvae, but are unexpected because they occur at a scale below the dispersal range of pelagic larvae. At the scale where most larvae are immigrants, theory predicts spatially homogeneous, temporally stable genetic variation. Empirical studies have suggested that genetic drift interacts with complex dispersal patterns to create chaotic genetic patchiness. Here we use a co-ancestry model and individual-based simulations to test this idea. We found that chaotic genetic patterns (qualified by global FST and spatio-temporal variation in FST's between pairs of samples) arise from the combined effects of (1) genetic drift created by the small local effective population sizes of the sessile phase and variance in contribution among breeding groups and (2) collective dispersal of related individuals in the larval phase. Simulations show that patchiness levels qualitatively comparable to empirical results can be produced by a combination of strong variance in reproductive success and mild collective dispersal. These results call for empirical studies of the effective number of breeders producing larval cohorts, and population genetics at the larval stage.
混沌遗传斑块表示在精细尺度上观察到的、不稳定的遗传分化的意外模式。这些模式在具有自由生活幼虫的海洋物种中已经被描述，但它们的出现是出乎意料的，因为它们发生在浮游幼虫的扩散范围之下。在大多数幼虫是移民的尺度上，理论预测遗传变异具有空间均匀、时间稳定的特征。实证研究表明，遗传漂变与复杂的扩散模式相互作用，导致了混沌遗传斑块。在这里，我们使用亲缘关系模型和基于个体的模拟来检验这个想法。我们发现，混沌遗传模式（由全局 FST 和成对样本之间 FST 的时空变化来限定）是由以下两个因素共同作用产生的：（1）固着阶段的小局部有效种群大小和繁殖群体之间的贡献方差所产生的遗传漂变；（2）幼虫阶段相关个体的集体扩散。模拟结果表明，通过繁殖成功率的强方差和轻度集体扩散的组合，可以产生与经验结果定性可比的斑块程度。这些结果呼吁对产生幼虫群体的有效繁殖者数量进行实证研究，并对幼虫阶段的种群遗传学进行研究。
