Data from: Developmental stress increases reproductive success in male zebra finches

There is increasing evidence that exposure to stress during development can have sustained effects on animal phenotype and performance across life-history stages. For example, developmental stress is known to decrease the quality of sexually selected traits (e.g. bird song), and therefore is thought to decrease reproductive success. However, animals exposed to developmental stress may compensate for poor quality sexually selected traits by pursuing alternative reproductive tactics. Here, we examine the effects of developmental stress on adult male reproductive investment and success in zebra finches (Taeniopygia guttata). We tested the hypothesis that males exposed to developmental stress sire fewer offspring through extra-pair copulations (EPCs), but invest more in parental care. To test this hypothesis, we fed nestlings corticosterone (CORT; the dominant avian stress hormone) during the nestling period and measured their adult reproductive success using common garden breeding experiments. We found that nestlings reared by CORT-fed fathers received more parental care compared to nestlings reared by control fathers. Consequently, males fed CORT during development reared nestlings in better condition compared to control males. Contrary to the prediction that developmental stress decreases male reproductive success, we found that CORT-fed males also sired more offspring, and were less likely to rear non-genetic offspring compared to control males, and thus had greater overall reproductive success. These data are the first to demonstrate that developmental stress can have a positive effect on fitness via changes in reproductive success and provide support for an adaptive role of developmental stress in shaping animal phenotype.

越来越多的证据表明，发育阶段暴露于应激环境会对动物在整个生活史阶段的表型（phenotype）与生存表现产生持久影响。例如，已知发育应激会降低性选择性状（sexually selected traits）的品质（例如鸣禽的鸣唱），因此被认为会降低繁殖成功率。然而，经历发育应激的动物可通过采取替代性繁殖策略（alternative reproductive tactics），弥补性选择性状品质不佳的缺陷。本研究以斑胸草雀（Taeniopygia guttata）为研究对象，探究发育应激对成年雄性繁殖投入与繁殖成功的影响。我们检验了如下假说：发育阶段暴露于应激的雄性，通过婚外配（extra-pair copulations, EPCs）产下的后代更少，但会在育幼投入上付出更多。为验证该假说，我们在雏鸟阶段给斑胸草雀幼雏饲喂皮质酮（corticosterone, CORT，鸟类主要的应激激素），并通过同质园繁殖实验测定其成年后的繁殖成功率。我们发现，由发育阶段饲喂过皮质酮的雄性亲鸟抚育的雏鸟，其获得的育幼照料相较于对照组雄性亲鸟抚育的雏鸟更多。由此可见，发育阶段饲喂皮质酮的雄性个体，其抚育的雏鸟身体状况优于对照组雄性。与"发育应激会降低雄性繁殖成功"的预测相悖，我们发现饲喂皮质酮的雄性产下的后代更多，且相较于对照组雄性，它们更不容易抚育非亲生后代，因此整体繁殖成功率更高。本数据集首次证实，发育应激可通过改变繁殖成功对动物适合度（fitness）产生积极影响，并为发育应激在塑造动物表型中具有适应性作用提供了支撑。