When a social species inhabits disparate environments with different requirements, it presents an ideal study framework for investigating plasticity in social structure. Common dolphins (Delphinus delphis) are wide-ranging offshore delphinids that generally form societies with fission-fusion dynamics within large schools and exhibit weak social bonds. In Port Phillip, southeastern Australia, common dolphins of the same species are, against expectations, resident to an embayment. Residency in this species provides a unique opportunity to investigate whether their social structure resembles that of their offshore conspecifics with weak social bonds, or whether bay living leads to stronger social bonds. We investigated the social structure of 12 resident adult common dolphins, between 2007 and 2014, in Port Phillip. Network analyses revealed nonrandom associations and several strong bonds, a social structure unusual for this species. The study shows that the social structure of a wide-ranging gregarious species in Port Phillip reflects the requirements of a confined environment with limited but predictable resources. Their social structure in the bay resembles that of inshore delphinids, rather than of its own species. Our study highlights the extreme plasticity in social structure that common dolphins are capable of and the importance of the environment for social bonds.

中文翻译：

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普通海豚形成意想不到的强大社会纽带：对海豚科社会可塑性的洞察

当社会物种栖息在具有不同要求的不同环境时，它为研究社会结构的可塑性提供了理想的研究框架。普通海豚 ( Delphinus delphis) 是范围广泛的离岸海豚科动物，它们通常在大型学校内形成具有裂变融合动力学的社会，并表现出薄弱的社会联系。在澳大利亚东南部的菲利普港，同一种常见的海豚出人意料地栖息在海湾。居住在这个物种中提供了一个独特的机会来研究它们的社会结构是否类似于社会联系较弱的离岸同种物种，或者海湾生活是否会导致更强的社会联系。我们调查了 2007 年至 2014 年间在菲利普港的 12 只常驻成年普通海豚的社会结构。网络分析揭示了非随机关联和几个强大的联系，这是该物种不寻常的社会结构。研究表明，菲利普港的一个范围广泛的群居物种的社会结构反映了有限但可预测资源有限环境的要求。它们在海湾中的社会结构类似于近海海豚科动物，而不是它自己的物种。我们的研究强调了普通海豚在社会结构中的极端可塑性以及环境对社会纽带的重要性。