Centre for Ecology & Hydrology, Bush Estate, Penicuik EH26 0QB, United Kingdom.
University of Glasgow, Graham Kerr Building, Glasgow G12 8QQ, United Kingdom.
Gen Comp Endocrinol. 2015 Jan 1;210:38-45. doi: 10.1016/j.ygcen.2014.10.003. Epub 2014 Oct 20.
Determining the physiological mechanisms underpinning life-history decisions is essential for understanding the constraints under which life-history strategies can evolve. In long-lived species, where the residual reproductive value of breeders is high, adult survival is a key contributor to lifetime reproductive success. We therefore expect that when adult survival is compromised during reproduction, mechanisms will evolve to redirect resources away from reproduction, with implications for reproductive hormones, adult body mass, nest attendance behaviour and breeding success. We investigated whether manipulating corticosterone, to simulate exposure to an environmental stressor, affected the secretion of prolactin and breeding success in the black-legged kittiwake Rissa tridactyla. We used implanted Alzet® osmotic pumps to administer corticosterone to incubating kittiwakes at a constant rate over a period of approximately 8days. Manipulated birds were compared with sham implanted birds and control birds, which had no implants. There was no significant difference in the body mass of captured individuals at the time of implantation and implant removal. Corticosterone-implanted males showed lower nest attendance during the chick rearing period compared to sham-implanted males; the opposite pattern was found in females. Corticosterone treated birds showed a marginally significant reduction in breeding success compared to sham-implanted individuals, with all failures occurring at least 1week after implant removal. However, prolactin concentrations at implant removal were not significantly different from initial values. We were unable to measure the profile of change in corticosterone during the experiment. However, our results suggest a delayed effect of elevated corticosterone on breeding success rather than an immediate suppression of prolactin concentrations causing premature failure.
确定生命史决策背后的生理机制对于理解生命史策略进化的约束条件至关重要。在长寿物种中，繁殖者的剩余生殖价值较高，因此成年个体的存活率是其终生繁殖成功的关键因素。因此，我们预计当繁殖过程中成年个体的存活率受到影响时，会进化出一些机制来将资源从繁殖中转移出来，这可能会影响生殖激素、成年个体体重、巢内出勤行为和繁殖成功率。我们研究了是否通过操纵皮质醇（模拟暴露于环境压力源）来影响黑脚三趾鸥（Rissa tridactyla）的催乳素分泌和繁殖成功率。我们使用植入的 Alzet®渗透泵以恒定速率向正在孵化的黑脚三趾鸥持续释放皮质醇约 8 天。将处理组与假植入组和未植入组的对照组进行比较。在植入和取出植入物时，捕获个体的体重没有显著差异。与假植入组相比，皮质醇处理的雄性在育雏期间的巢内出勤次数较少；而在雌性中则发现了相反的模式。与假植入个体相比，皮质醇处理组的繁殖成功率略有下降，所有失败都发生在取出植入物后至少 1 周。然而，在取出植入物时，催乳素浓度与初始值没有显著差异。我们无法测量实验过程中皮质醇变化的情况。然而，我们的结果表明，皮质醇升高对繁殖成功率的影响是延迟的，而不是立即抑制催乳素浓度导致过早失败。
