Data from: Female reproductive competition in Eulemur rufifrons: eviction and reproductive restraint in a plurally breeding Malagasy primate

In mammals with female philopatry, co-resident females inevitably compete with each other for resources or reproductive opportunities, thereby reducing the kin-selected benefits of altruism towards relatives. These counteracting forces of cooperation and competition among kin should be particularly pronounced in plurally breeding species with limited alternative breeding opportunities outside the natal group. However, little is still known about the costs of reproductive competition on females’ fitness and the victims’ potential counter-strategies. Here we summarize long-term behavioral, demographic and genetic data collected on a plurally breeding primate from Madagascar to illuminate mechanisms and effects of female reproductive competition, focusing on forcible eviction and potential reproductive restraint. The main results of our study indicate that females in groups of redfronted lemurs (Eulemur rufifrons) above a critical size suffer from competition from their close relatives: females in larger groups face an increased probability of not giving birth as well as a higher probability of being evicted, especially during the annual mating and birth seasons. Eviction is not predicted by the number of adult females, the number of close female relatives, female age or inter-annual variation in rainfall but only by total group size. Thus, eviction in this species is clearly linked with reproductive competition, it cannot be forestalled by reproductive restraint or having many relatives in the group, and it occurs in the absence of a clear dominance hierarchy. Our study therefore also underscores the notion that potential inclusive fitness benefits from living with relatives may have been generally over-rated and should not be taken for granted.在具有雌性恋家（female philopatry）习性的哺乳动物中，同群雌性不可避免地会为资源或繁殖机会彼此竞争，进而削弱利他行为对亲属带来的亲缘选择收益。这种亲属间合作与竞争的抵消效应，在那些除出生群外缺乏其他繁殖途径的多雌繁殖物种中尤为显著。然而，学界目前对繁殖竞争对雌性适合度带来的代价，以及受竞争雌性的潜在应对策略仍知之甚少。本研究汇总了针对马达加斯加一种群居繁殖灵长类的长期行为、种群统计与遗传数据，以阐明雌性繁殖竞争的机制与影响，重点关注强制驱逐行为与潜在的繁殖抑制策略。本研究的主要结果显示，当群规模超过临界值时，红额狐猴（Eulemur rufifrons）群体中的雌性会遭受近亲的竞争：群规模更大时，雌性无法生育的概率以及被驱逐的概率均会升高，这一现象在每年的交配与产仔季尤为突出。驱逐行为的发生与成年雌性数量、近亲雌性数量、雌性年龄或年际降雨波动均无关联，仅与总群规模相关。因此，该物种的驱逐行为显然与繁殖竞争直接相关，既无法通过繁殖抑制加以避免，也不会因群体内拥有较多近亲而得到缓解，且发生于不存在明确优势等级的群体中。本研究同时也印证了一个观点：与亲属同群生活所能带来的潜在广义适合度（inclusive fitness）收益或许被普遍高估，这一收益不应被想当然地视为理所当然。