Atlantic white-sided dolphins (Lagenorhynchus acutus) are highly social odontocetes with a poorly understood tendency to mass strand. With limited capacity to study social ecology in the open ocean, mass strandings provide an opportunity to improve our understanding of group structure. Our study of 32 mass stranding events that occurred on Cape Cod, Massachusetts, between 1999 and 2009 identifies aspects of social ecology that vary across the year. A greater number of mass stranding events occurred outside of the breeding season and there was evidence of age-structuring during the breeding season. We find generally low average intragroup pairwise relatedness assessed across eight microsatellite loci in a subset of 16 mass stranding events. Mass stranded groups do not show higher than expected relatedness when compared to a baseline estimate derived from single-stranded individuals. Overall, our integration of genetic estimates of relatedness with data on sex and maturity-class from stranded specimens suggests that Atlantic white-sided dolphins fall near the more fluid end of the continuum from short-term, highly fluid social associations to long-term, stable groups represented among the odontocetes. Despite their tendency to mass strand, stable, kin-based associations are not a defining feature of social group structure in this species.

中文翻译：

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搁浅提供了对大西洋白海豚社会群体结构的洞察

大西洋白边海豚 ( Lagenorhynchus acutus) 是高度社会化的齿鲸，对大众链的趋势知之甚少。由于在公海中研究社会生态的能力有限，大规模搁浅提供了一个机会来提高我们对群体结构的理解。我们对 1999 年至 2009 年间发生在马萨诸塞州科德角的 32 起大规模搁浅事件的研究确定了全年变化的社会生态方面。更多的大规模搁浅事件发生在繁殖季节之外，并且有证据表明繁殖季节期间存在年龄结构。我们发现在 16 个大规模搁浅事件的子集中的 8 个微卫星位点上评估的平均组内成对相关性普遍较低。与从单链个体得出的基线估计值相比，大规模搁浅群体并未表现出高于预期的相关性。全面的，我们将相关性的遗传估计与搁浅标本的性别和成熟度数据相结合表明，大西洋白海豚从短期、高度流动的社会交往到长期、稳定的群体，接近连续体的流动性更强的一端以齿鲸为代表。尽管它们倾向于群体链，但稳定的、基于亲属的关联并不是该物种社会群体结构的定义特征。