A novel mammalian social structure in Indo-Pacific bottlenose dolphins (Tursiops sp.): complex male alliances in an open social network

作者：Randic Srdan; Connor Richard C^*; Sherwin William B; Kruetzen Michael

来源：Proceedings of the Royal Society B, 2012, 279(1740): 3083-3090.

DOI：10.1098/rspb.2012.0264

• alliances
• ranges
• social structure
• social organization

Terrestrial mammals with differentiated social relationships live in %26apos;semi-closed groups%26apos; that occasionally accept new members emigrating from other groups. Bottlenose dolphins (Tursiops sp.) in Shark Bay, Western Australia, exhibit a fission-fusion grouping pattern with strongly differentiated relationships, including nested male alliances. Previous studies failed to detect a group membership %26apos;boundary%26apos;, suggesting that the dolphins live in an open social network. However, two alternative hypotheses have not been excluded. The community defence model posits that the dolphins live in a large semi-closed %26apos;chimpanzee-like%26apos; community defended by males and predicts that a dominant alliance(s) will range over the entire community range. The mating season defence model predicts that alliances will defend mating-season territories or sets of females. Here, both models are tested and rejected: no alliances ranged over the entire community range and alliances showed extensive overlap in mating season ranges and consorted females. The Shark Bay dolphins, therefore, present a combination of traits that is unique among mammals: complex male alliances in an open social network. The open social network of dolphins is linked to their relatively low costs of locomotion. This reveals a surprising and previously unrecognized convergence between adaptations reducing travel costs and complex intergroup-alliance relationships in dolphins, elephants and humans.

• 出版日期2012-8-7