Levréro Florence, Gatti Sylvain, Ménard Nelly, Petit Eric, Caillaud Damien, Gautier-Hion Annie
Université Rennes 1, CNRS UMR 6552, Ethologie-Evolution-Ecologie, Station Biologique, Paimpont, France.
Am J Primatol. 2006 Mar;68(3):275-91. doi: 10.1002/ajp.20223.
The one-male reproductive strategy implies that maturing males are temporarily excluded from reproduction. In gorillas, these excluded males live either solitarily or in nonbreeding groups (NBGs) that are devoid of adult females. The dynamics of NBGs are not well known. In this study, which was conducted on a gorilla population (Gorilla gorilla gorilla) of 377 individuals that visited the Lokoué clearing in the Republic of Congo, we detail how the NBGs formed, and analyze their dynamics according to age-sex classes, the relatedness of members, and the origin and destination of transferring individuals. We discuss the potential benefits gained by individuals living in these groups. The NBGs included mainly immature males, most of which appeared to have migrated voluntarily from their natal groups. Some individuals (including juvenile females) came from disbanded breeding groups (BGs). Migrants preferentially joined NBGs that included a silverback male. Their dispersal patterns were not determined by their degree of relatedness, but they tended to associate with related silverbacks. In this way, the migrants could enhance their protection against predators and gain experience with different environmental conditions. By tolerating and protecting offspring, aging silverbacks could enhance their inclusive fitness. Finally, young and healthy silverbacks could increase their likelihood of forming a future BG when unrelated females joined them.
单雄性繁殖策略意味着成熟雄性会暂时被排除在繁殖之外。在大猩猩中，这些被排除的雄性要么独居，要么生活在没有成年雌性的非繁殖群体（NBGs）中。非繁殖群体的动态情况尚不为人所知。在这项针对刚果共和国洛库埃空地的377只大猩猩种群（西部低地大猩猩）开展的研究中，我们详细阐述了非繁殖群体是如何形成的，并根据年龄-性别类别、群体成员的亲缘关系以及迁移个体的来源和去向，分析了它们的动态变化。我们讨论了生活在这些群体中的个体所获得的潜在益处。非繁殖群体主要由未成年雄性组成，其中大多数似乎是自愿从出生群体迁移而来的。一些个体（包括未成年雌性）来自解散的繁殖群体（BGs）。迁移者优先加入包含一只成年雄性大猩猩的非繁殖群体。它们的扩散模式并非由亲缘关系程度决定，但它们倾向于与有亲缘关系的成年雄性大猩猩为伴。通过这种方式，迁移者可以增强自身对捕食者的防御能力，并在不同环境条件下积累经验。通过容忍和保护后代，年老的成年雄性大猩猩可以提高其广义适合度。最后，当无关雌性加入时，年轻健康的成年雄性大猩猩组建未来繁殖群体的可能性会增加。
