Garant Dany, Dodson Julian J, Bernatchez Louis
Université Laval, Département de Biologie, Sainte-Foy, Quebec G1K 7P4 Canada.
Evolution. 2003 May;57(5):1133-41. doi: 10.1111/j.0014-3820.2003.tb00322.x.
A critical step in understanding the evolution and maintenance of alternative reproductive tactics is to obtain accurate comparisons of their fitness and to determine factors influencing individual status. In this study, we first used individual multilocus genotypic information to compare reproductive success between two alternative reproductive tactics of anadromous Atlantic salmon (Salmo salar L.) in their natural environments. We also documented the effects of the quality of the rearing environment and of paternal reproductive tactics on heritability of juvenile growth, which is an important component of individual status. Results showed that large dominant salmon (multisea winter) had higher reproductive success than smaller satellite individuals (grilse). Also, there was a status difference associated with both habitat and male tactic. Overall, offspring produced in streams were bigger than those produced in the main river stretch. Grilse also produced bigger offspring than those fathered by multisea winter males. Heritability of juvenile growth was significant but varied according to quality of habitat: higher heritability estimates were observed in higher quality habitats (streams) than in lower quality habitats (main river stretch). Heritability estimates for juvenile growth varied as well, depending on male tactic, with progeny fathered by multisea winter males having higher values than those fathered by grilse. Together, these results indicate that a combination of additive genetic effects, parental life history and habitat quality will ultimately shape juvenile growth rate, which is the main determinant of status and of subsequent choice of life-history tactics.
理解替代繁殖策略的进化与维持的关键一步，是准确比较它们的适合度，并确定影响个体状态的因素。在本研究中，我们首先利用个体多位点基因型信息，比较溯河洄游型大西洋鲑（Salmo salar L.）在自然环境中的两种替代繁殖策略之间的繁殖成功率。我们还记录了饲养环境质量和父本繁殖策略对幼鱼生长遗传力的影响，幼鱼生长是个体状态的一个重要组成部分。结果表明，大型优势鲑鱼（多海龄）的繁殖成功率高于小型卫星个体（降河洄游型幼鲑）。此外，在栖息地和雄鱼策略方面都存在状态差异。总体而言，在溪流中产出的后代比在主河道产出的后代体型更大。降河洄游型幼鲑产出的后代也比多海龄雄鱼产出的后代体型更大。幼鱼生长的遗传力显著，但因栖息地质量而异：在高质量栖息地（溪流）中观察到的遗传力估计值高于低质量栖息地（主河道）。幼鱼生长的遗传力估计值也因雄鱼策略而异，多海龄雄鱼产出的后代的遗传力值高于降河洄游型幼鲑产出的后代。总之，这些结果表明，加性遗传效应、亲本生活史和栖息地质量的综合作用最终将塑造幼鱼生长率，而幼鱼生长率是个体状态及后续生活史策略选择的主要决定因素。
