Department of Limnology, University of Pannonia, Pf. 158, H-8201 Veszprém, Hungary.
Mol Ecol. 2009 Nov;18(22):4696-706. doi: 10.1111/j.1365-294X.2009.04363.x. Epub 2009 Sep 22.
Social behaviour of group-living animals is often influenced by the relatedness of individuals, thus understanding the genetic structure of groups is important for the interpretation of costs and benefits of social interactions. In this study, we investigated genetic relatedness in feeding aggregations of free-living house sparrows (Passer domesticus) during the nonbreeding season. This species is a frequent model system for studies of social behaviour (e.g. aggression, social foraging), but we lack adequate information on the kin structure of sparrow flocks. During two winters, we ringed and observed sparrows at feeding stations, and used resightings to identify stable flock-members and to calculate association indices between birds. We genotyped the birds using seven highly polymorphic microsatellite loci, and estimated pairwise relatedness coefficients and relatedness categories (close kin vs. unrelated) by maximum likelihood method. We found that most birds were unrelated to each other in the flocks (mean +/- SE relatedness coefficient: 0.06 +/- 0.002), although most individuals had at least a few close relatives in their home flock (14.3 +/- 0.6% of flock-mates). Pairwise association between individuals was not significantly related to their genetic relatedness. Furthermore, there was no difference between within-flock vs. between-flock relatedness, and birds had similar proportions of close kin within and outside their home flock. Finally, relatedness among members of different flocks was unrelated to the distance between their flocks. Thus, sparrow flocks were not characterized by association of relatives, nevertheless the presence of some close kin may provide opportunity for kin-biased behaviours to evolve.
群居动物的社会行为通常受个体间亲缘关系的影响，因此了解群体的遗传结构对于解释社会互动的成本和收益很重要。在这项研究中，我们在非繁殖季节调查了自由生活的麻雀（Passer domesticus）觅食群聚中的遗传亲缘关系。这种物种是研究社会行为（如攻击、社会觅食）的常见模式系统，但我们对麻雀群聚的亲缘结构信息知之甚少。在两个冬季，我们在喂食站给麻雀佩戴环志并进行观察，并通过再识别来确定稳定的群聚成员，并计算鸟类之间的关联指数。我们使用七个高度多态性的微卫星基因座对鸟类进行基因分型，并使用最大似然法估计个体间的亲缘关系系数和亲缘关系类别（近亲与无关）。我们发现，大多数鸟类在群聚中彼此之间没有亲缘关系（平均 +/- SE 亲缘关系系数：0.06 +/- 0.002），尽管大多数个体在其家庭群聚中至少有一些近亲（14.3 +/- 0.6% 的群聚同伴）。个体之间的成对关联与它们的遗传亲缘关系没有显著关系。此外，群内与群间的亲缘关系没有差异，鸟类在家庭群聚内外具有相似比例的近亲。最后，不同群聚成员之间的亲缘关系与它们的群聚之间的距离无关。因此，麻雀群聚并没有表现出亲缘关系的关联，但一些近亲的存在可能为亲缘偏好行为的进化提供机会。
