Department of Evolutionary Physiology, Max Planck Institute for Ornithology, Seewiesen, Starnberg, Germany
Department of Evolutionary Physiology, Max Planck Institute for Ornithology, Seewiesen, Starnberg, Germany.
Proc Biol Sci. 2018 Nov 28;285(1892):20182141. doi: 10.1098/rspb.2018.2141.
The trade-off between reproductive investment and survival is central to life-history theory, but the relative importance and the complex interactions among the physiological mechanisms mediating it are still debated. Here we experimentally tested whether baseline glucocorticoid hormones, the redox system or their interaction mediate reproductive investment-survival trade-offs in wild great tits (). We increased the workload of parental males by clipping three feathers on each wing, and 5 days later determined effects on baseline corticosterone concentrations (Cort), redox state (reactive oxygen metabolites, protein carbonyls, glutathione peroxidase [GPx], total non-enzymatic antioxidants), body mass, body condition, reproductive success and survival. Feather-clipping did not affect fledgling numbers, chick body condition, nest provisioning rates or survival compared with controls. However, feather-clipped males lost mass and increased both Cort and GPx concentrations. Within feather-clipped individuals, GPx increases were positively associated with reproductive investment (i.e. male nest provisioning). Furthermore, within all individuals, males that increased GPx suffered reduced survival rates. Baseline Cort increases were related to mass loss but not to redox state, nest provisioning or male survival. Our findings provide experimental evidence that changes in the redox system are associated with the trade-off between reproductive investment and survival, while baseline Cort may support this trade-off indirectly through a link with body condition. These results also emphasize that plastic changes in individuals, rather than static levels of physiological signals, may mediate life-history trade-offs.
生殖投资与生存之间的权衡是生活史理论的核心，但调节这种权衡的生理机制的相对重要性和复杂相互作用仍存在争议。在这里，我们通过实验测试了基础糖皮质激素、氧化还原系统或它们之间的相互作用是否介导了野生大山雀（）的生殖投资-生存权衡。我们通过剪掉每只翅膀上的三根羽毛来增加亲鸟雄性的工作量，然后在 5 天后确定其对基础皮质酮浓度（Cort）、氧化还原状态（活性氧代谢物、蛋白质羰基、谷胱甘肽过氧化物酶 [GPx]、总非酶抗氧化剂）、体重、身体状况、繁殖成功率和存活率的影响。与对照组相比，剪羽并未影响雏鸟数量、雏鸟的身体状况、筑巢供应率或存活率。然而，剪羽的雄性与对照组相比，体重减轻，皮质酮和 GPx 浓度增加。在剪羽的个体中，GPx 的增加与生殖投资（即雄性筑巢供应）呈正相关。此外，在所有个体中，GPx 增加的雄性存活率降低。基础 Cort 的增加与体重减轻有关，但与氧化还原状态、筑巢供应或雄性存活率无关。我们的研究结果提供了实验证据，表明氧化还原系统的变化与生殖投资和生存之间的权衡有关，而基础 Cort 可能通过与身体状况的联系间接支持这种权衡。这些结果还强调，个体的可塑性变化，而不是生理信号的静态水平，可能介导生活史权衡。
