Kin association during brood care in a facultatively social bird: active discrimination or byproduct of partner choice and demography?

Intra-group relatedness does not necessarily imply kin selection, a leading explanation for social evolution. An overlooked mechanism for generating population genetic structure is variation in longevity and fecundity, referred to as individual quality, affecting kin structure and the potential for cooperation. Individual quality also affects choosiness in partner choice, a key process explaining cooperation through direct fitness benefits. Reproductive skew theory predicts that relatedness decreases with increasing group size, but this relationship could also arise due to quality-dependent demography and partner choice, without active kin association. We addressed whether brood-rearing eider (Somateria mollissima) females preferentially associated with kin using a six-year data set with individuals genotyped at 19 microsatellite loci, and tested whether relatedness decreased with increasing female group size. We also determined the relationship between local relatedness and indices of ...

群体内亲缘关联未必等同于亲缘选择（kin selection），后者是社会演化领域的主流解释之一。种群遗传结构形成的一个被忽视的机制是寿命与繁殖力的变异，该变异被称为个体质量（individual quality），可影响亲缘结构与合作演化的潜力。个体质量还会影响配偶选择（partner choice）中的择偶偏好，这一过程是通过直接适合度收益（direct fitness benefits）阐释合作演化的核心机制。繁殖偏斜理论（reproductive skew theory）预测，亲缘关联会随群体规模扩大而降低，但该关联也可仅由依赖个体质量的种群统计特征与配偶选择所导致，无需主动的亲缘聚集行为。本研究依托一项涵盖19个微卫星位点（microsatellite loci）基因分型个体的6年长期数据集，探讨了育雏期绒鸭（Somateria mollissima）雌性是否会优先与亲缘个体聚集，并检验了亲缘关联是否随雌性群体规模扩大而降低。本研究还分析了局域亲缘关联与……指标之间的关联关系。