The Law School, University of Chicago, Chicago, Illinois, United States of America.
PLoS One. 2011;6(5):e19853. doi: 10.1371/journal.pone.0019853. Epub 2011 May 16.
The spatiotemporal distribution of females is thought to drive variation in mating systems, and hence plays a central role in understanding animal behavior, ecology and evolution. Previous research has focused on investigating the links between female spatiotemporal distribution and the number of males in haplorhine primates. However, important questions remain concerning the importance of spatial cohesion, the generality of the pattern across haplorhine and strepsirrhine primates, and the consistency of previous findings given phylogenetic uncertainty. To address these issues, we examined how the spatiotemporal distribution of females influences the number of males in primate groups using an expanded comparative dataset and recent advances in bayesian phylogenetic and statistical methods. Specifically, we investigated the effect of female distributional factors (female number, spatial cohesion, estrous synchrony, breeding season duration and breeding seasonality) on the number of males in primate groups. Using bayesian approaches to control for uncertainty in phylogeny and the model of trait evolution, we found that the number of females exerted a strong influence on the number of males in primate groups. In a multiple regression model that controlled for female number, we found support for temporal effects, particularly involving female estrous synchrony: the number of males increases when females are more synchronously receptive. Similarly, the number of males increases in species with shorter birth seasons, suggesting that greater breeding seasonality makes defense of females more difficult for male primates. When comparing primate suborders, we found only weak evidence for differences in traits between haplorhines and strepsirrhines, and including suborder in the statistical models did not affect our conclusions or give compelling evidence for different effects in haplorhines and strepsirrhines. Collectively, these results demonstrate that male monopolization is driven primarily by the number of females in groups, and secondarily by synchrony of female reproduction within groups.
雌性的时空分布被认为是交配系统变异的驱动因素，因此在理解动物行为、生态学和进化方面起着核心作用。以前的研究主要集中在调查阔鼻猴和原猴类动物的雌性时空分布与雄性数量之间的联系。然而，关于空间凝聚的重要性、阔鼻猴和原猴类动物中模式的普遍性以及鉴于系统发育不确定性以前研究结果的一致性，仍有一些重要的问题需要解决。为了解决这些问题，我们使用扩展的比较数据集和贝叶斯系统发育和统计方法的最新进展，研究了雌性的时空分布如何影响灵长类动物群体中的雄性数量。具体来说，我们调查了雌性分布因素（雌性数量、空间凝聚、发情同步、繁殖季节持续时间和繁殖季节性）对灵长类动物群体中雄性数量的影响。我们使用贝叶斯方法来控制系统发育和性状进化模型的不确定性，发现雌性数量对灵长类动物群体中的雄性数量有很大的影响。在控制雌性数量的多元回归模型中，我们发现支持时间效应的证据，特别是涉及雌性发情同步：当雌性更同步地接受时，雄性数量增加。同样，在繁殖季节较短的物种中，雄性数量增加，这表明繁殖季节性越强，雄性灵长类动物防御雌性就越困难。在比较灵长类动物的亚目时，我们发现阔鼻猴和原猴类动物之间的特征差异只有微弱的证据，并且在统计模型中包括亚目并没有影响我们的结论，也没有为阔鼻猴和原猴类动物的不同影响提供令人信服的证据。总的来说，这些结果表明，雄性的垄断主要是由群体中的雌性数量驱动的，其次是群体中雌性繁殖的同步性。
