Leimberger Kara G, Lewis Rebecca J
Department of Anthropology, University of Texas at Austin, Austin, Texas.
Am J Primatol. 2017 Jul;79(7). doi: 10.1002/ajp.22455. Epub 2015 Aug 7.
Males of many group-living mammals emigrate from their social groups to improve mating opportunities. To help mitigate the social and locational costs of dispersal and to increase reproductive benefits, they may immigrate seasonally, immigrate alongside a partner, and/or replace the alpha male (versus entering a group as a subordinate). Verreaux's sifaka (Propithecus verreauxi) are highly seasonally breeding primates characterized by male-biased dispersal. We hypothesized that (i) males time immigrations to pursue immediate mating opportunities, (ii) entrances with partners more often result in alpha male replacement, and (iii) male competitive ability affects immigration strategy and alpha male tenure length. To assess these proximate aspects of male dispersal, we examined 7 years of demographic, morphological, and behavioral data for five social groups of Verreaux's sifaka in the Kirindy Mitea National Park in western Madagascar. Contrary to expectations and studies of sifaka dispersal in other populations, we detected no strong seasonal pattern in immigrations. Immigrations occurred individually and with partners, and a trend existed for partners to increase the likelihood of replacing an alpha male. Pronounced activity of the sternal scent gland (a proxy for testosterone and prior dominance status), but not body mass, canine size, or potential correlates of leaping ability, significantly influenced immigration strategy. The absence of a seasonal immigration pattern suggests that fluid group boundaries may allow mating success without establishment in a social group before the mating season. Our results also suggest that male immigration strategies are affected by age, prior dominance status, and testosterone levels but not morphological indicators of individual competitive ability. Coalitions may be used to improve competitive ability. Finally, differences in seasonal immigration patterns and length of alpha male vacancies observed at Kirindy Mitea may be due to the relatively low population density. Am. J. Primatol. 79:e22455, 2017. © 2015 Wiley Periodicals, Inc.
许多群居哺乳动物的雄性会从它们的社会群体中迁出，以增加交配机会。为了帮助减轻扩散的社会和位置成本，并提高繁殖效益，它们可能会季节性迁入、与伴侣一起迁入，和/或取代优势雄性（而不是作为从属个体进入群体）。维氏冕狐猴（Propithecus verreauxi）是高度季节性繁殖的灵长类动物，其特征是雄性偏向扩散。我们假设：（i）雄性选择迁入时间以追求即时交配机会；（ii）与伴侣一起迁入更常导致优势雄性被取代；（iii）雄性竞争能力影响迁入策略和优势雄性任期长度。为了评估雄性扩散的这些直接因素，我们研究了马达加斯加西部基林迪米泰国家公园中五个维氏冕狐猴社会群体的7年人口统计学、形态学和行为数据。与预期以及对其他种群中冕狐猴扩散的研究相反，我们没有发现迁入存在强烈的季节性模式。迁入个体发生，也有与伴侣一起的情况，并且伴侣有增加取代优势雄性可能性的趋势。胸骨气味腺的明显活动（睾酮和先前优势地位的指标），而非体重、犬齿大小或跳跃能力的潜在相关因素，显著影响迁入策略。缺乏季节性迁入模式表明，灵活的群体边界可能使在交配季节前未在社会群体中立足的情况下也能获得交配成功。我们的结果还表明，雄性迁入策略受年龄、先前优势地位和睾酮水平影响，但不受个体竞争能力的形态学指标影响。联盟可能被用来提高竞争能力。最后，在基林迪米泰观察到的季节性迁入模式和优势雄性空缺期长度的差异可能是由于相对较低的种群密度。《美国灵长类学杂志》79:e22455，2017年。©2015威利期刊公司
