Sexual segregation in Indo-Pacific bottlenose dolphins is driven by female avoidance of males
Sexual segregation in Indo-Pacific bottlenose dolphins is driven by female avoidance of males
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DOI：
10.1093/beheco/arx177
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发表时间：
2018-03-01
影响因子：
2.4
通讯作者：
Mann, Janet
中科院分区：
文献类型：
--
作者：
Galezo, Allison A.;Krzyszczyk, Ewa;Mann, Janet
在许多物种中，雄性和雌性彼此隔离，因为它们分配不同的时间，以不同的食物为食，或容忍捕食者不同。在印度-太平洋海豚中，雄性的攻击性可以阻止混合性别的群体。当雄性和雌性相遇时，雄性经常加入雌性，而雌性经常离开雄性。雌性动物可能会躲避雄性动物以避免攻击。性隔离在哺乳动物中很普遍，尽管在单态物种中的近因知之甚少。印度-太平洋短吻海豚（Tursiops aduncus），表现出高度的裂变-融合动力学，提供了一个有用的透镜来研究性别隔离的生态和社会驱动因素。虽然生态假说表明，性别隔离是性别特异性生态偏好的副产品（例如，与栖息地、觅食或捕食者回避有关），社会假说提出种族隔离是由同性偏好造成的（例如，由于合作利益）和/或异性回避（例如，由于竞争或剥削的相互作用）。印度太平洋海豚的雌性范围从几乎孤独到高度社会化。雄性会结成联盟，相互合作，以隔离单个雌性，并排除竞争的雄性。鉴于相关性胁迫的证据，我们的主要假设是，性隔离是由女性避免侵略性男性驱动的。然而，鉴于性别偏见觅食策略的有力证据，生态因素可能也有贡献。使用性别隔离和聚集统计数据，跨越31年的17，468个目击记录，我们发现了强烈的性别隔离。我们的工作是独一无二的，我们分析了焦点观察（N = 10，715个裂变-融合事件，87个女性，111个男性）中男性和女性之间的连接和离开的方向，以确定哪种性别驱动性别隔离。女性很少加入男性，而且经常离开男性，从而推动了种族隔离。虽然生态因素可能会加强性别隔离，但社会因素占主导地位。这项研究表明，在一个社会复杂的野生哺乳动物种群的裂变融合动力学的性别偏见，并提供了强有力的经验支持的性别隔离的社会假说。
In many species, males and females segregate from each other because they allocate time differently, forage on different foods, or tolerate predators differently. In Indo-Pacific bottlenose dolphins, male aggression can deter mixed-sex groups. When males and females encounter each other, males often join females while females often leave males. Females likely evade males to avoid aggression.Sexual segregation is widespread in mammals, although the proximate causes are poorly understood in monomorphic species. Indo-Pacific bottlenose dolphins (Tursiops aduncus), which exhibit a high degree of fission-fusion dynamics, offer a useful lens to examine the ecological and social drivers of sexual segregation. While ecological hypotheses suggest that sexual segregation is a by-product of sex-specific ecological preferences (e.g., related to habitat, foraging, or predator avoidance), the social hypothesis proffers that segregation results from same-sex preferences (e.g., due to cooperative benefits) and/or opposite-sex avoidance (e.g., due to competitive or exploitative interactions). Indo-Pacific bottlenose dolphin females range from nearly solitary to highly sociable. Males associate in alliances that cooperate to sequester individual females and exclude competing males. Given evidence for allied sexual coercion, our primary hypothesis was that sexual segregation is driven by female avoidance of aggressive males. However, given robust evidence for sex-biased foraging tactics, ecological factors likely also contribute. Using the Sexual Segregation and Aggregation Statistic with 17,468 sighting records spanning 31 years, we found strong sexual segregation. Unique to our work, we analyzed the direction of joins and leaves between males and females from focal observations (N = 10,715 fission-fusion events, 87 females, 111 males) to determine which sex drives sexual segregation. Females drove segregation by rarely joining and often leaving males. Although ecological factors likely reinforce sexual segregation, social factors predominate. This study demonstrates a sex-bias in fission-fusion dynamics in a socially complex wild mammal population and offers strong empirical support to the social hypothesis of sexual segregation.