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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在动物园饲养的老虎和狐猴中，寿命随着雄性的比例而降低，而雌性则不降低。

多项研究表明，在雄性比雌性更大的哺乳动物中，养育儿子的成本要高于女儿。这些研究通常关注女性，方法是检查单个生殖事件中的后代性别比例如何影响母亲随后的生殖或存活概率。在这里，我们使用来自动物园饲养的老虎（Panthera tigris）和r狐猴（Varecia sp。）的数据，检查了单次或多次生殖事件中的后代性别比与父母中的几种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儿子对母亲的较高成本。在雄性狐猴中，早年（10岁之前）生下的儿子比例与晚年寿命成负相关。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丸激素水平的差异：高浓度的睾丸激素会增加儿子的比例并损害免疫功能。我们的研究结果表明，在野生种群中进行的研究应解决在理解男性性别分配的后果方面的艰巨挑战，并为在保护环境下预测寿命提供机会。