Centre Interuniversitaire de Recherche sur le Saumon Atlantique (CIRSA) and Québec-Océan, Université Laval, Québec, QC, Canada.
J Evol Biol. 2011 Feb;24(2):245-55. doi: 10.1111/j.1420-9101.2010.02159.x. Epub 2010 Nov 2.
Migratory behaviour with its associated phenotypic changes is generally viewed as an adaptive strategy because it incurs survival or reproductive advantages to migrants. The development of a migrant phenotype is believed to be controlled by threshold mechanisms, where individuals emigrate only after surpassing a particular body size but delay migration if below. For such a strategy to respond to natural selection, part of the phenotypic variance in the propensity to migrate must be explained by variation in additive genetic effects. Here, we use data gathered in the field and from a common rearing experiment to test for a genetic basis associated with seaward migration in Atlantic salmon (Salmo salar L.). We document a high heritability of the liability trait underlying the propensity to emigrate in juvenile salmon, and significant differences between offspring grouped according to their sires in body-size threshold values above which emigration takes place. The presence of additive genetic variance in both the liability and thresholds makes the onset of migration a process sensitive to selection and may therefore constitute an important explanatory mechanism for the interpopulation differences in the size at seaward migration observed in this species.
迁徙行为及其相关的表型变化通常被视为一种适应性策略，因为它为迁徙者带来了生存或繁殖优势。迁徙表型的发展被认为是由阈值机制控制的，只有个体超过特定的体型才会迁徙，但如果低于这个体型就会延迟迁徙。为了使这种策略对自然选择产生反应，迁徙倾向的表型方差的一部分必须由加性遗传效应的变化来解释。在这里，我们利用野外和共同饲养实验收集的数据，来检验与大西洋鲑（Salmo salar L.）向海迁徙相关的遗传基础。我们记录了幼鲑鱼中潜在的迁徙倾向的 Liability 性状具有较高的遗传力，并且根据它们的父亲，在体型阈值之上发生迁徙的情况下，后代之间存在显著差异。 Liability 和阈值都存在加性遗传方差，这使得迁徙的开始成为一个对选择敏感的过程，因此可能构成了该物种中观察到的向海迁徙大小的种群间差异的一个重要解释机制。
