Pomilla Cristina, Rosenbaum Howard C
New York University, Department of Biology, 100 Washington Square East, New York, NY 10003, USA.
Mol Ecol. 2006 Aug;15(9):2541-55. doi: 10.1111/j.1365-294X.2006.02943.x.
Group formation in humpback whales has been described in relation to different components of the migratory cycle, yet it is debated whether such groups represent real social bonding or ephemeral aggregations. Cooperative behaviours are exhibited during feeding activities, and it has been suggested that males may cooperate during competition for mates. Since most cooperative behaviours are expected to originate among kin, genetic relatedness represents a critical variable in the understanding of any social phenomenon, especially when cooperation cannot be confirmed unequivocally. Using an approach combining multi-locus microsatellite genotyping and several genetic relatedness estimators, we analyzed whale associations for two different wintering grounds in the Southern Hemisphere. The analyses included 648 whales sampled from 292 groups off the coast of Gabon and Northeast Madagascar, and screened for eleven microsatellite loci. Through simulations, we assessed the performance of three pairwise relatedness estimators. The individuals were molecularly sexed and their associations were investigated in the context of sex and group type. No significant association among relatives was found with the exception of mother-offspring pairs, supporting previous indications of extended maternal care. The analysis from the Gabon population also suggests that related males may avoid each other during competitive activities. Our results demonstrate that if cooperative behaviours occur on wintering grounds they are not favoured by kin selection.
座头鲸群体的形成已被描述为与洄游周期的不同组成部分相关，但这些群体是代表真正的社会联系还是短暂的聚集仍存在争议。在觅食活动中会表现出合作行为，并且有人提出雄性在争夺配偶时可能会合作。由于大多数合作行为预计起源于亲属之间，遗传相关性是理解任何社会现象的关键变量，尤其是在合作不能明确确认的情况下。我们采用多基因座微卫星基因分型和几种遗传相关性估计方法相结合的方式，分析了南半球两个不同越冬地的鲸鱼群体。分析包括从加蓬海岸和马达加斯加东北部的292个群体中采样的648头鲸鱼，并对11个微卫星基因座进行了筛选。通过模拟，我们评估了三种成对相关性估计方法的性能。对个体进行了分子性别鉴定，并在性别和群体类型的背景下研究了它们的群体关系。除了母仔对之外，未发现亲属之间有显著关联，这支持了之前关于延长母性照料的迹象。对加蓬种群的分析还表明，相关雄性在竞争活动中可能会相互避开。我们的结果表明，如果合作行为发生在越冬地，它们不受亲缘选择的青睐。
