Masi Shelly, Austerlitz Frédéric, Chabaud Chloé, Lafosse Sophie, Marchi Nina, Georges Myriam, Dessarps-Freichey Françoise, Miglietta Silvia, Sotto-Mayor Andrea, Galli Aurore San, Meulman Ellen, Pouydebat Emmanuelle, Krief Sabrina, Todd Angelique, Fuh Terence, Breuer Thomas, Ségurel Laure
UMR7206 Eco-anthropologie Muséum national d'Histoire naturelle CNRS Université de Paris; Musée de l'Homme Paris France.
Department of Biology Ecole normale supérieure PSL University Paris Paris France.
Ecol Evol. 2021 May 25;11(12):7634-7646. doi: 10.1002/ece3.7596. eCollection 2021 Jun.
Characterizing animal dispersal patterns and the rational behind individuals' transfer choices is a long-standing question of interest in evolutionary biology. In wild western gorillas (), a one-male polygynous species, previous genetic findings suggested that, when dispersing, females might favor groups with female kin to promote cooperation, resulting in higher-than-expected within-group female relatedness. The extent of male dispersal remains unclear with studies showing conflicting results. To investigate male and female dispersal patterns and extragroup paternity, we analyzed long-term field observations, including female spatial proximity data, together with genetic data (10 autosomal microsatellites) on individuals from a unique set of four habituated western gorilla groups, and four additional extragroup males (49 individuals in total). The majority of offspring (25 of 27) were sired by the group male. For two offspring, evidence for extragroup paternity was found. Contrarily to previous findings, adult females were not significantly more related within groups than across groups. Consistently, adult female relatedness within groups did not correlate with their spatial proximity inferred from behavioral data. Adult females were similarly related to adult males from their group than from other groups. Using statistics, we found significant genetic structure and a pattern of isolation by distance, indicating limited dispersal in this species. Comparing relatedness among females and among males revealed that males disperse farer than females, as expected in a polygamous species. Our study on habituated western gorillas shed light on the dispersal dynamics and reproductive behavior of this polygynous species and challenge some of the previous results based on unhabituated groups.
描述动物的扩散模式以及个体迁移选择背后的原理，是进化生物学中一个长期以来备受关注的问题。在野生西部大猩猩（一种一雄多雌的物种）中，先前的遗传学研究结果表明，雌性在扩散时可能会倾向于选择有雌性亲属的群体以促进合作，从而导致群体内雌性之间的亲缘关系高于预期。而雄性扩散的程度仍不明确，各项研究结果相互矛盾。为了研究雄性和雌性的扩散模式以及群体外父权情况，我们分析了长期的野外观察数据，包括雌性空间接近度数据，以及来自一组独特的四个习惯化西部大猩猩群体和另外四个群体外雄性个体（总共49个个体）的遗传数据（10个常染色体微卫星）。大多数后代（27个中的25个）是由群体中的雄性所生。对于两个后代，发现了群体外父权的证据。与先前的研究结果相反，成年雌性在群体内的亲缘关系并不比群体间的显著更高。同样，根据行为数据推断，群体内成年雌性的亲缘关系与其空间接近度并无关联。成年雌性与群体内成年雄性的亲缘关系和与其他群体成年雄性的亲缘关系相似。通过统计分析，我们发现了显著的遗传结构和距离隔离模式，表明该物种的扩散有限。比较雌性之间和雄性之间的亲缘关系发现，正如在一夫多妻制物种中预期的那样，雄性的扩散距离比雌性更远。我们对习惯化西部大猩猩的研究揭示了这种一雄多雌物种的扩散动态和繁殖行为，并对一些基于未习惯化群体的先前研究结果提出了挑战。
