No sex-biased dispersal in a primate with an uncommon social system—cooperative polyandry
No sex-biased dispersal in a primate with an uncommon social system—cooperative polyandry
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灵长类动物不存在性别偏见，具有不寻常的社会制度——合作性一妻多夫制
作者：
Samuel L. Díaz;Ângela M. Ribeiro
Greenwood（1980）提出的一个有影响力的假说认为，不同的交配系统分别导致鸟类和哺乳动物的雌性和雄性偏向扩散。然而，社会结构和行为的其他方面也可以塑造性别偏见的扩散。虽然性别特异性模式的亲属合作，预计会影响philopatry和分散模式的好处，经验证据是稀缺的。与许多哺乳动物不同，Saguinus geoffroyi（Geoffroy的绢毛猴）有一个繁殖系统，其中通常有多个雄性与一个繁殖雌性交配。雄性通常在亲属之间形成合作的生殖伙伴关系，而雌性通常竞争生殖机会。这一系统的合作一妻多夫预计将导致女性偏向的传播，提供了一个机会来测试目前的假设性别偏向的传播。在这里，我们测试的证据，性别偏见的传播在S。geoffroyi使用来自三个人群的人口统计学和遗传学数据。我们没有发现纳塔尔扩散的性别偏见，相反的预测的基础上的交配模式。在控制了历史人口结构的影响后，这种模式是一致的。有限的社会群体内的繁殖机会可能会驱使男性和女性分散，这表明分散是密切相关的社会背景。遗传和现场数据的整合显示，绢毛猴是另一个例外的假定模式，男性偏见的传播哺乳动物。从交配系统到社会行为的焦点转移，在大多数预期影响传播中性别偏见的过程中发挥作用，将是物种内和跨类群研究的一个富有成效的目标。
An influential hypothesis proposed by Greenwood (1980) suggests that different mating systems result in female and male-biased dispersal, respectively, in birds and mammals. However, other aspects of social structure and behavior can also shape sex-biased dispersal. Although sex-specific patterns of kin cooperation are expected to affect the benefits of philopatry and dispersal patterns, empirical evidence is scarce. Unlike many mammals, Saguinus geoffroyi (Geoffroy’s tamarin) has a breeding system in which typically multiple males mate with a single breeding female. Males typically form cooperative reproductive partnerships between relatives, whereas females generally compete for reproductive opportunities. This system of cooperative polyandry is predicted to result in female-biased dispersal, providing an opportunity to test the current hypotheses of sex-biased dispersal. Here we test for evidence of sex-biased dispersal in S. geoffroyi using demographic and genetic data from three populations. We find no sex bias in natal dispersal, contrary to the prediction based on the mating patterns. This pattern was consistent after controlling for the effects of historical population structure. Limited breeding opportunities within social groups likely drive both males and females to disperse, suggesting that dispersal is intimately related to the social context. The integration of genetic and field data revealed that tamarins are another exception to the presumed pattern of male-biased dispersal in mammals. A shift in focus from mating systems to social behavior, which plays a role in most all processes expected to influence sex-bias in dispersal, will be a fruitful target for research both within species and across taxa.