Stable group size in cooperative breeders: the role of inheritance and reproductive skew
Stable group size in cooperative breeders: the role of inheritance and reproductive skew
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DOI：
10.1093/beheco/arj065
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发表时间：
2006-07-01
影响因子：
2.4
通讯作者：
English, Sinead
中科院分区：
文献类型：
--
作者：
Cant, Michael A.;English, Sinead
最近关于生殖偏差的研究揭示了群体成员之间直接适应度分布的巨大差异，但令人惊讶的是，很少有人试图探索这种差异对稳定群体规模的影响，也没有人考虑到群体成员身份对非繁殖者未来的好处。这意味着，现有的理论不适合解释大多数合作繁殖的脊椎动物和原始群居昆虫的群体规模，在这些群体中，群体成员关系到未来的巨大利益。在这里，我们将这类物种的群体规模建模为社会队列，在这种队列中，如果非繁殖者比队列中排在他们前面的人活得更长，他们就可以继承繁殖地位。然而，我们证明了这些结果可以推广到通过置乱竞争而不是通过严格的队列进行继承的系统。该模型预测，稳定的种群规模将取决于种群中繁殖位置的数量以及繁育者和非繁育者的死亡率，而不是繁殖者在繁殖者池中的分布。这是因为死亡是随机发生的，所以每个个体都有相同的机会存活到每个繁殖地点。我们使用黄蜂的卵巢发育数据测试了该模型的一个特定预测。正如预测的那样，我们发现群体大小与雌性卵子完全发育的比例呈正相关。我们的结果阐明了动物群体的优势结构和大小之间的相互作用，并进一步认识到遗传作为动物社会个体行为和群体水平特征的主要决定因素的潜力日益增长。
Recent studies of reproductive skew have revealed great variation in the distribution of direct fitness among group members, yet there have been surprisingly few attempts to explore the consequences of such variation for stable group size, and none that take into account the future benefits of group membership to nonbreeders. This means that the existing theory is not suited to explain the group size of most cooperatively breeding vertebrates and primitively social insects in which group membership involves substantial future benefits. Here we model the group size of such species as social queues in which nonbreeders can inherit a breeding position if they outlive those ahead of them in the queue. We demonstrate, however, that the results can be generalized to systems in which inheritance occurs via scramble competition, rather than via a strict queue. The model predicts that stable group size will depend on the number of breeding positions in the group and the mortality rates of breeders and nonbreeders, but not on the distribution of reproduction among the pool of breeders. This is because deaths occur at random, so that each individual has the same chance of surviving to reach each breeding position. We tested a specific prediction of the model using data on ovarian development in the paper wasp, Polistes dominulus. We found a positive correlation between group size and the proportion of females with fully developed eggs, as predicted. Our results clarify the interaction between the dominance structure and size of animal groups and add to the growing recognition of the potential for inheritance as a major determinant of both individual behavior and group-level characteristics of animal societies.