Data from: Paternal care and litter size coevolution in mammals

Biparental care of offspring occurs in diverse mammalian genera, and is particularly common among species with socially monogamous mating systems. Despite numerous well-documented examples however, the evolutionary causes and consequences of paternal care in mammals are not well understood. Here we investigate the evolution of paternal care in relation to offspring production. Using comparative analyses to test for evidence of evolutionary associations between male care and life history traits, we explore if biparental care is likely to have evolved because of the importance of male care to offspring survival, or if evolutionary increases in offspring production are likely to result from the evolution of biparental care. Overall, we find no evidence that paternal care has evolved in response to benefits of supporting females to rear particularly costly large offspring or litters. Rather, our findings suggest that increases in offspring production are more likely to follow the evolution of paternal care, specifically where males contribute depreciable investment such as provisioning young. Through coevolution with litter size, we conclude that paternal care in mammals is likely to play an important role in stabilising monogamous mating systems and could ultimately promote the evolution of complex social behaviours.

后代的双亲抚育（biparental care）广泛存在于多样的哺乳动物类群中，在实行社会一夫一妻制婚配体系（socially monogamous mating systems）的物种里尤为常见。尽管已有大量被充分记录的实例，但哺乳动物雄性抚育行为的进化成因与演化后果仍未得到充分阐明。本研究围绕后代产出展开，探究雄性抚育行为的演化机制。我们采用比较分析（comparative analyses）方法，检验雄性抚育与生活史性状（life history traits）之间的演化关联证据，探讨双亲抚育的演化是否源于雄性抚育对后代存活的关键作用，抑或是后代产出的进化提升由双亲抚育的演化所驱动。总体而言，我们未发现雄性抚育的演化是为了获得辅助雌性抚育高成本大型幼崽或多仔产仔的收益的相关证据。与之相反，本研究结果显示，后代产出的提升更可能紧随雄性抚育的演化而来，尤其是在雄性会提供可损耗性亲代投入（如为幼崽提供食物）的类群中。通过与产仔数（litter size）的协同演化分析，我们得出结论：哺乳动物的雄性抚育行为可能在稳定一夫一妻制婚配体系中发挥重要作用，并最终可能促进复杂社会行为的演化。