Yang Xi, Berman Carol M, Hu Hanyu, Hou Rong, Huang Kang, Wang Xiaowei, Zhao Haitao, Wang Chengliang, Li Baoguo, Zhang Pei
Shaanxi Key Laboratory for Animal Conservation, College of Life Sciences, Northwest University, Xi'an 710069, China.
Department of Anthropology and Graduate Program in Evolution, Ecology and Behavior, State University of New York at Buffalo, NY 14261, USA.
Curr Zool. 2021 May 26;68(2):133-142. doi: 10.1093/cz/zoab044. eCollection 2022 Apr.
Age is a key factor affecting sexual selection, as many physical and social traits are age-related. Although studies of primate mate choice often consider particular age-related traits, few consider the collective effects of male age. We tested the hypothesis that female golden snub-nosed monkeys prefer prime aged males (10-15 years) over younger and older males. We examined a habituated, provisioned troop during a 3-year study in the Qinling Mountains, China. Prime age males were more likely to be resident males of 1-male units (OMUs) than males of other ages. Since females are free to transfer between OMUs, the number of females per OMU can be indicative of female preferences. We examined the number of females per OMU, and found that it increased with resident male age up to 7-8 years, and declined after 12 years, such that prime age resident males had more females than other resident males. Females also initiated extra-unit copulations with high-ranking prime age males at significantly higher rates than with other males. Nevertheless, females tended to transfer from OMUs with high-ranking, older resident males to those with low-ranking, younger resident males. Thus, females appear to use different strategies when choosing social mates and extra-unit mates (i.e., different social contexts). We speculate that females may perceive early signs of aging in males and trade off the benefits and costs of high rank versus male senescence. This study lays the groundwork for future studies that examine possible direct and indirect benefits of such strategies.
年龄是影响性选择的关键因素，因为许多生理和社会特征都与年龄相关。尽管对灵长类动物配偶选择的研究通常会考虑特定的与年龄相关的特征，但很少有研究考虑雄性年龄的综合影响。我们检验了一个假设，即雌性川金丝猴更喜欢壮年雄性（10 - 15岁）而非年轻和年长的雄性。在中国秦岭地区进行的一项为期3年的研究中，我们观察了一个习惯化且有食物供应的猴群。壮年雄性比其他年龄段的雄性更有可能成为单雄单元（OMU）的常驻雄性。由于雌性可以自由地在不同的OMU之间转移，每个OMU中的雌性数量可以表明雌性的偏好。我们研究了每个OMU中的雌性数量，发现其随着常驻雄性年龄的增长而增加，直到7 - 8岁，之后在12岁后下降，因此壮年常驻雄性比其他常驻雄性拥有更多的雌性。雌性与高等级壮年雄性进行单元外交配的频率也显著高于与其他雄性。然而，雌性倾向于从拥有高等级、年长常驻雄性的OMU转移到拥有低等级、年轻常驻雄性的OMU。因此，雌性在选择社会配偶和单元外配偶时（即不同的社会背景下）似乎采用了不同的策略。我们推测雌性可能察觉到雄性衰老的早期迹象，并在高等级的益处与雄性衰老的成本之间进行权衡。这项研究为未来研究此类策略可能带来的直接和间接益处奠定了基础。
