Fraser Dylan J, Duchesne Pierre, Bernatchez Louis
Québec Océan, Département de Biologie, Université Laval, Québec, Canada G1V 2C7.
Mol Ecol. 2005 Sep;14(10):3133-46. doi: 10.1111/j.1365-294X.2005.02657.x.
Few studies have critically investigated the genetic composition of wild fish schools. Yet, such investigations may have profound implications for the understanding of social organization and population differentiation in both fundamental and applied research. Using 20 microsatellite loci, we investigated the composition of 53 schools (total n = 211) of adult and subadult migratory brook charr (Salvelinus fontinalis) sampled from the known feeding areas of two populations inhabiting Mistassini Lake (Québec, Canada). We specifically tested whether (i) school members originated from the same population, (ii) individuals from the same population within schools were kin (half- or full-siblings), and (iii) kin schooling relationships differed between sexes. Randomization tests revealed a tendency for most schools to be population specific, although some schools were population mixtures. Significantly more kin were found within schools than expected at random for both populations (approximately 21-34% of the total number of school members). This result, combined with the observed size range of individuals, indicated that stable associations between kin may occur beyond juvenile stages for up to 4 years. Nevertheless, a high proportion of school members were non-kin (approximately 66-79%). No differences were detected between sexes in the propensity to school with kin. We discuss the hypothesis that the stable kin groups, rather than arising from kin selection, may instead be a by-product of familiarity based on individual selection for the maintenance of local adaptations related to migration (natal and feeding area philopatry). Our results are noteworthy because they suggest that there is some degree of permanence in the composition of wild fish schools. Additionally, they support the hypothesis that schools can be hierarchically structured (from population members down to family groups) and are thus nonrandom genetic entities.
很少有研究对野生鱼群的基因组成进行批判性调查。然而，此类调查可能对基础研究和应用研究中社会组织和种群分化的理解具有深远意义。我们使用20个微卫星位点，对从加拿大魁北克米斯塔西尼湖两个种群已知觅食区域采集的53群（总数n = 211）成年和亚成年洄游溪红点鲑（Salvelinus fontinalis）的组成进行了调查。我们特别测试了：（i）鱼群成员是否来自同一种群；（ii）鱼群中来自同一种群的个体是否为亲属（半同胞或全同胞）；以及（iii）亲属群居关系在性别之间是否存在差异。随机化测试表明，尽管有些鱼群是种群混合体，但大多数鱼群倾向于特定种群。两个种群中，鱼群内亲属的数量均显著多于随机预期数量（约占鱼群成员总数的21 - 34%）。这一结果，结合观察到的个体大小范围，表明亲属之间的稳定关联可能在幼体阶段之后持续长达4年。然而，很大比例的鱼群成员是非亲属（约66 - 79%）。在与亲属群居的倾向方面，未检测到性别差异。我们讨论了这样一种假设，即稳定的亲属群体并非源于亲属选择，而可能是基于个体选择以维持与洄游相关的局部适应性（出生地和觅食地的留居性）所产生的熟悉度的副产品。我们的结果值得注意，因为它们表明野生鱼群的组成存在一定程度的持久性。此外，它们支持了鱼群可以分层构建（从种群成员到家族群体）这一假设，因此是非随机的基因实体。
