Department of Anthropology, University of Wisconsin, Madison, WI 53706, USA.
Proc Natl Acad Sci U S A. 2011 Nov 22;108(47):18915-9. doi: 10.1073/pnas.1116737108. Epub 2011 Nov 7.
Levels of reproductive skew vary in wild primates living in multimale groups depending on the degree to which high-ranking males monopolize access to females. Still, the factors affecting paternity in egalitarian societies remain unexplored. We combine unique behavioral, life history, and genetic data to evaluate the distribution of paternity in the northern muriqui (Brachyteles hypoxanthus), a species known for its affiliative, nonhierarchical relationships. We genotyped 67 individuals (22 infants born over a 3-y period, their 21 mothers, and all 24 possible sires) at 17 microsatellite marker loci and assigned paternity to all infants. None of the 13 fathers were close maternal relatives of females with which they sired infants, and the most successful male sired a much lower percentage of infants (18%) than reported for the most successful males in other species. Our findings of inbreeding avoidance and low male reproductive skew are consistent with the muriqui's observed social and sexual behavior, but the long delay (≥2.08 y) between the onset of male sexual behavior and the age at which males first sire young is unexpected. The allocation of paternity implicates individual male life histories and access to maternal kin as key factors influencing variation in paternal--and grandmaternal--fitness. The apparent importance of lifelong maternal investment in coresident sons resonates with other recent examinations of maternal influences on offspring reproduction. This importance also extends the implications of the "grandmother hypothesis" in human evolution to include the possible influence of mothers and other maternal kin on male reproductive success in patrilocal societies.
在多雄群体中生活的野生灵长类动物中，繁殖优势度的水平存在差异，这取决于高等级雄性垄断雌性资源的程度。然而，平等社会中影响亲权的因素仍未得到探索。我们结合独特的行为、生活史和遗传数据，评估了北方毛里求斯猕猴（Brachyteles hypoxanthus）的亲权分布，该物种以其亲和、非等级关系而闻名。我们在 17 个微卫星标记基因座上对 67 个个体（22 个在 3 年期间出生的婴儿、他们的 21 个母亲以及所有 24 个可能的父亲）进行了基因型分析，并将亲权分配给了所有婴儿。13 个父亲中没有一个是与他们生育婴儿的雌性有密切母系关系的亲属，最成功的雄性生育的婴儿比例（18%）远低于其他物种中最成功雄性的报告比例。我们发现避免近亲繁殖和低雄性繁殖优势度的现象与毛里求斯猕猴的观察到的社会和性行为一致，但雄性性行为开始与雄性首次生育幼崽之间的时间延迟（≥2.08 年）出乎意料。亲权的分配暗示了个体雄性的生活史和获得母系亲属的机会是影响父系和祖母系适应性差异的关键因素。母亲对核心居住儿子的终身投资的重要性与最近对母亲对后代繁殖影响的其他研究结果相呼应。这种重要性还将“祖母假说”在人类进化中的意义扩展到包括母亲和其他母系亲属对父系社会中雄性生殖成功的可能影响。
