Lecomte Nicolas, Gauthier Gilles, Giroux Jean-François, Milot Emmanuel, Bernatchez Louis
Département de Biologie and Centre d'Etudes Nordiques, Université Laval, Québec, QC, Canada G1V 0A6.
Mol Ecol. 2009 Feb;18(4):593-602. doi: 10.1111/j.1365-294X.2008.04067.x. Epub 2009 Jan 21.
Nonrandom dispersal has been recently advanced as a mechanism promoting fine-scale genetic differentiation in resident populations, yet how this applies to species with high rates of dispersal is still unclear. Using a migratory species considered a classical example of male-biased dispersal (the greater snow goose, Chen caerulescens atlantica), we documented a temporally stable fine-scale genetic clustering between spatially distinct rearing sites (5-30 km apart), where family aggregates shortly after hatching. Such genetic differentiation can only arise if, in both sexes, dispersal is restricted and nonrandom, a surprising result considering that pairing occurs among mixed flocks of birds more than 3000 km away from the breeding grounds. Fine-scale genetic structure may thus occur even in migratory species with high gene flow. We further show that looking for genetic structure based on nesting sites only may be misleading. Genetically distinct individuals that segregated into different rearing sites were in fact spatially mixed during nesting. These findings provide new, scale-dependent links between genetic structure, pairing, and dispersal and show the importance of sampling different stages of the breeding cycle in order to detect a spatial genetic structure.
非随机扩散最近被认为是促进定居种群精细尺度遗传分化的一种机制，但这一机制如何适用于扩散率高的物种仍不清楚。我们以一种被视为雄性偏向扩散典型例子的迁徙物种（大雪雁，Chen caerulescens atlantica）为研究对象，记录了在空间上不同的育雏地点（相距5 - 30公里）之间存在的时间上稳定的精细尺度遗传聚类现象，雏鸟孵化后不久家族就聚集于此。这种遗传分化只有在两性的扩散都受到限制且是非随机的情况下才会出现，考虑到配对发生在距离繁殖地3000多公里外的混合鸟群中，这一结果令人惊讶。因此，即使在基因流动高的迁徙物种中也可能出现精细尺度的遗传结构。我们进一步表明，仅基于筑巢地点寻找遗传结构可能会产生误导。实际上，在筑巢期间，那些在遗传上不同且分属于不同育雏地点的个体在空间上是混合的。这些发现提供了遗传结构、配对和扩散之间新的、依赖尺度的联系，并表明了在繁殖周期的不同阶段进行采样以检测空间遗传结构的重要性。
