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.

在具有雌性留守出生地（female philopatry）习性的哺乳动物中，共居雌性不可避免地会为争夺资源或繁殖机会而彼此竞争，进而削弱利他行为带给亲属的亲缘选择收益。这类亲属间合作与竞争的反向制衡作用，在那些缺乏出生地外其他繁殖途径的多雌共栖繁殖物种中表现得尤为显著。
然而，目前学界对雌性繁殖竞争给其适合度带来的代价，以及受竞争影响的雌性可能采取的反制策略仍所知有限。本研究汇总了针对马达加斯加一种多雌共栖繁殖灵长类的长期行为学、种群统计学与遗传学数据，旨在阐明雌性繁殖竞争的作用机制与影响效应，重点关注强制性驱逐行为与潜在的繁殖抑制策略。
本研究的核心结果显示，当红额狐猴（Eulemur rufifrons）的群体规模超过临界值时，群体内的雌性会受到近亲的竞争压力：群体规模越大，雌性不孕的概率以及被驱逐的概率就越高，这种现象在年度交配与产仔季尤为突出。
是否遭遇驱逐与成年雌性数量、近亲雌性数量、雌性年龄或年际降雨量变化均无关联，仅与种群总规模相关。由此可见，该物种的雌性驱逐行为显然与繁殖竞争直接相关，既无法通过繁殖抑制或群体内拥有大量亲属来避免，也并非建立在明确的优势等级体系之上。
因此，本研究也印证了一个观点：与亲属共处所能带来的广义适合度（inclusive fitness）收益可能普遍被高估，这一收益并非理所当然。