Several studies have shown higher costs of rearing sons than daughters in mammals where males are larger than females. These studies typically focus on females by examining how the offspring sex ratio during a single reproductive event affected mothers' subsequent reproduction or survival probability. Here, we examine relationships between offspring sex ratio during single or multiple reproductive events and several survival metrics in mothers and fathers, using data from zoo-housed tigers (Panthera tigris) and ruffed lemurs (Varecia sp.). Our analyses failed to reveal an overall cost of reproduction or a higher cost of sons to mothers. In male ruffed lemurs, the proportion of sons produced during early life (before 10 years old) was negatively correlated with lifespan later in life. In tigers, males with a higher proportion of sons during their lifetime had shorter lifespans. One likely mechanism is the difference in testosterone levels between males: a high concentration of testosterone can increase the proportion of sons and compromise immune function. Our results suggest studies in wild populations should address the outstanding challenge of understanding consequences of sex allocation for males, and open an opportunity to predict lifespan in an applied conservation context.

中文翻译：

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动物园饲养的老虎和狐猴的寿命随着雄性而不是雌性的儿子比例而下降。

几项研究表明，在雄性比雌性大的哺乳动物中，养育儿子的成本高于养育女儿的成本。这些研究通常通过检查单个生殖事件期间后代的性别比例如何影响母亲随后的繁殖或生存概率来关注女性。在这里，我们使用来自动物园饲养的老虎 (Panthera tigris) 和狐猴 (Varecia sp.) 的数据，研究了单次或多次繁殖事件中后代性别比与母亲和父亲的几个生存指标之间的关系。我们的分析未能揭示生育的总体成本或母亲对儿子的更高成本。在雄性狐猴中，早年（10 岁之前）生子的比例与晚年的寿命呈负相关。在老虎中，一生中儿子比例较高的男性寿命较短。一种可能的机制是男性之间睾酮水平的差异：高浓度的睾酮会增加儿子的比例并损害免疫功能。我们的结果表明，对野生种群的研究应该解决理解男性性别分配后果的突出挑战，并为在应用保护环境中预测寿命提供机会。