Behavioral Ecology & Sociobiology Unit, German Primate Center, Göttingen, Germany.
Mol Ecol. 2012 Feb;21(3):685-98. doi: 10.1111/j.1365-294X.2011.05255.x. Epub 2011 Aug 31.
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 behavioural, 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.
在雌性具有亲代栖居习性的哺乳动物中，同居雌性不可避免地会相互竞争资源或生殖机会，从而降低了对亲属的利他行为的亲缘选择利益。在具有多种繁殖方式且在出生地群体之外繁殖机会有限的物种中，亲缘之间的合作与竞争的这些相互抵消的力量应该尤为明显。然而，对于生殖竞争对雌性适合度的代价以及受害者的潜在应对策略，人们仍然知之甚少。在这里，我们总结了在马达加斯加的一种多种繁殖灵长类动物上收集的长期行为、人口统计和遗传数据，以阐明雌性生殖竞争的机制和影响，重点关注强制驱逐和潜在的生殖抑制。我们研究的主要结果表明，红额狐猴（Eulemur rufifrons）群体中超过临界大小的雌性会受到近亲的竞争：较大群体中的雌性面临着更高的不生育概率和更高的被驱逐概率，尤其是在每年的交配和生育季节。驱逐并不取决于成年雌性的数量、近亲雌性的数量、雌性年龄或年际降雨量的变化，而仅取决于总群体大小。因此，在这个物种中，驱逐显然与生殖竞争有关，它不能通过生殖抑制或在群体中有许多亲属来阻止，而且它发生在没有明确的统治等级的情况下。因此，我们的研究也强调了这样一种观点，即与亲属生活在一起的潜在适合度利益可能被普遍高估，不应视为理所当然。
