Effects of endogenous steroid hormone levels on annual survival in Cliff Swallows
Effects of endogenous steroid hormone levels on annual survival in Cliff Swallows
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DOI：
10.1890/04-0740
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发表时间：
2005-04-01
期刊：
影响因子：
4.8
通讯作者：
Wingfield, JC
中科院分区：
文献类型：
--
作者：
Brown, CR;Brown, MB;Wingfield, JC
皮质酮激素是动物对环境压力作出反应的重要组成部分，调节行为和生理方面的短期适应性变化。睾酮激素也很关键，尤其对雄性而言，在调节性行为和亲代抚育的表现方面。然而，这些激素可能会产生代价高昂的后果，并且在种群内，个体的皮质酮和睾酮内源性水平存在差异。我们研究了2000 - 2003年在美国内布拉斯加州西南部群居繁殖的崖燕（Petrochelidon pyrrhonota）中，年存活率如何随着这些激素的自然水平而变化。我们对在栖息地捕获的鸟类的激素水平进行采样，并通过标记重捕法监测它们在研究区域后续年份的存活情况。最大似然估计和模型拟合（使用MARK程序）显示，在繁殖季后期从各种规模的栖息地采样的鸟类，其存活率呈曲线变化；皮质酮水平极低和极高的个体比中等水平的个体存活率更低。然而，在繁殖季早期采样的鸟类的年存活率通常随着皮质酮水平的升高而降低。考虑到存活函数，在当年后期未熏蒸的栖息地中，皮质酮水平极低的鸟类比预期的要多，这可能表明极低的皮质酮水平存在一种与存活无关的补偿性益处。在一项更有限的分析中，睾酮似乎对年存活率影响很小，尽管一些证据表明，在特定日期内源性睾酮水平低于平均值的雌性可能存活率更高。
The hormone corticosterone is an important part of animals ' response to environmental stress, modulating short-term adaptive changes in behavior and physiology. The hormone testosterone is also critical, especially for males, in regulating the expression of sexual behavior and parental care. These hormones can have costly consequences, however, and within populations individuals show variation in endogenous levels of both corficosterone and testosterone. We studied how annual survival varied as a function of natural levels of these hormones in colonially breeding Cliff Swallows (Petrochelidon pyrrhonota) in southwestern Nebraska, USA, in 2000-2003. We sampled hormone levels of birds caught at colonies and using mark-recapture, monitored their survival through subsequent years in the study area. Maximum-likelihood estimation and model fitting (with program MARK) revealed that birds sampled for corticosterone in colonies of all sizes late in the season had curvilinear survival; individuals with very low and very high levels of corticosterone had lower survival than those with intermediate levels. Annual survival of birds sampled earlier in the season, however, generally declined with increasing corticosterone level. More birds than expected, given the survival functions, had the very low corticosterone levels in nonfumigated colonies later in the year, suggesting perhaps a compensatory benefit unrelated to survival for very low corticosterone levels. In a more limited analysis, testosterone appeared to have little effect on annual survival, although some evidence suggested that females with endogenous testosterone levels below the mean for a given date might have survived better.