Glucocorticoid stress hormones and the effect of predation risk on elk reproduction
Glucocorticoid stress hormones and the effect of predation risk on elk reproduction
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DOI：
10.1073/pnas.0902235106
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发表时间：
2009-07-28
影响因子：
11.1
通讯作者：
Christianson, David
中科院分区：
文献类型：
--
作者：
Creel, Scott;Winnie, John A., Jr.;Christianson, David
捕食者通过直接捕食和反捕食者行为反应的代价或风险效应来影响猎物的种群结构。实验表明，风险效应可以构成捕食者对猎物动态的总影响的很大一部分，但我们对它们在野生种群中的强度或介导它们的生理机制知之甚少。当狼出现时，麋鹿会改变它们的分组模式、警惕性、觅食行为、栖息地选择和饮食。这些反应与孕酮水平降低、产犊量降低和种群规模减小相关[Creel S，Christianson D，Liley S，温妮JA（2007）科学315：960]。捕食风险对繁殖的影响有两种一般机制：捕食应激假说和捕食者敏感食物假说。在这里，我们使用酶免疫测定法测量粪便糖皮质激素代谢物浓度为1,205个样本收集4个麋鹿种群超过4个冬天，以检验这一假设，捕食风险对麋鹿繁殖的影响是由慢性应激介导的。在不同的人群和年份中，粪便糖皮质激素浓度与捕食者-猎物比率、孕酮浓度或小牛-母牛比率无关。总体而言，狼的存在对麋鹿繁殖的影响更好地解释了觅食模式的变化，携带营养成本比糖皮质激素浓度的变化。
Predators affect prey demography through direct predation and through the costs of antipredator behavioral responses, or risk effects. Experiments have shown that risk effects can comprise a substantial proportion of a predator's total effect on prey dynamics, but we know little about their strength in wild populations, or the physiological mechanisms that mediate them. When wolves are present, elk alter their grouping patterns, vigilance, foraging behavior, habitat selection, and diet. These responses are associated with decreased progesterone levels, decreased calf production, and reduced population size [Creel S, Christianson D, Liley S, Winnie JA (2007) Science 315: 960]. Two general mechanisms for the effect of predation risk on reproduction have been proposed: the predation stress hypothesis and the predator-sensitive-food hypothesis. Here, we used enzyme immunoassay to measure fecal glucocorticoid metabolite concentrations for 1,205 samples collected from 4 elk populations over 4 winters to test the hypothesis that the effect of predation risk on elk reproduction is mediated by chronic stress. Across populations and years, fecal glucocorticoid concentrations were not related to predator-prey ratios, progesterone concentrations or calf-cow ratios. Overall, the effect of wolf presence on elk reproduction is better explained by changes in foraging patterns that carry nutritional costs than by changes in glucocorticoid concentrations.