Proximate and ultimate drivers of an unusual adult sex ratio in redfronted lemurs (Eulemur rufifrons)

在大多数哺乳动物物种中，包括人类，雄性和雌性在年龄特异性生存方面表现出差异，通常导致雌性偏向的成年性别比率（ASR）。关于健康和生存方面年龄和性别相关差异的数据可以揭示生物适应方面的基本性别差异，但这类数据对于野生种群极其缺乏，对于具有异常偏倚asr的物种则难以获得。因此，我们提出的研究的主要目标是(i)确定具有雄性偏性ASR的红额狐猴野生种群的年龄和性别特异性生存模式，评估（ii）健康和生存决定因素的年龄和性别特异性变化，以及（iii）有助于生存的机制，以了解其从出生到死亡的性别比例的模式和动态。为了实现这些目标，我们将结合三个数据集，即长期人口统计数据，先前研究的激素，遗传和行为数据，以及新的生理和行为数据。通过研究性别和年龄在生存、免疫能力、寄生、脆弱、社会缓冲和冒险方面的相关差异，我们的研究将是第一个研究野生灵长类动物种群健康和生存性别差异的适应性意义和近似机制的研究之一。因此，它还将为更好地理解人类男性-女性健康-生存悖论提供比较视角，并构成对野生哺乳动物一生中性别比例变化驱动因素的最全面分析之一。

In most mammalian species, including humans, males and females exhibit differences in age-specific survival, usually resulting in female-biased adult sex ratios (ASR). Data on age and sex-related variation in health and survival can reveal fundamental sex differences in biological adaptations, but such data are extremely scarce for wild populations and unavailable for species with unusually biased ASRs. The main objectives of our proposed study are therefore (i) to determine age- and sex-specific survival patterns for a wild population of redfronted lemurs with male-biased ASR, to assess (ii) age- and sex-specific variation in determinants of health and survival, as well as (iii) mechanisms that contribute to survival to understand the patterns and dynamics of their sex ratios from birth to death. To achieve these objectives, we will combine three data sets, i.e., long-term demographic data, hormonal, genetic and behavioral data from previous studies, and new physiological and behavioral data. By examining sex- and age-related variation in survival, immunocompetence, parasitism, frailty, social buffering and risk-taking, our study will be among the first to investigate the adaptive significance and proximate mechanisms underlying sex differences in health and survival in a wild primate population. As such, it will also contribute comparative perspectives for a better understanding of the human male-female health-survival paradox as well as constitute one of the most comprehensive analyses of the drivers of sex ratio variation across the lifespan in wild mammals.