Early elevation of testosterone advances migratory preparation in a songbird
Early elevation of testosterone advances migratory preparation in a songbird
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睾丸激素的早期升高促进鸣禽的迁徙准备
DOI：
10.1242/jeb.054734
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发表时间：
2011
影响因子：
2.8
通讯作者：
R. Holberton
中科院分区：
文献类型：
--
作者：
C. Tonra;P. Marra;R. Holberton
与春季迁徙相关的事件的时间可能是候鸟适应性的重要决定因素。为迁徙做好准备和保持身体状况是提前到达繁殖地必须满足的一项要求，而这一要求又与向繁殖地生理过渡的精力需求相辅相成。在这里，我们研究了候鸟，特别是雄性候鸟，是否可以通过在迁徙准备的早期提高性类固醇睾丸激素来充分满足这两种需求。为了验证这一点，我们使用了一个圈养实验，在这个实验中，我们光刺激雄性黑眼Junco （Junco hyemalis）并操纵循环睾酮。我们预测，睾酮水平升高的雄性会比对照雄性或睾酮与受体结合或转化为雌二醇的能力受到抑制的雄性准备迁移和繁殖得更快。我们用质量、食物摄入量、脂肪沉积和夜间活动（Zugunruhe）来测量迁徙准备。为了估计繁殖准备，我们测量了泄殖腔突起（CP）的直径。我们发现睾酮治疗组的男性大约比对照组早10天开始迁移准备。注射睾酮的鸟类和对照组的迁徙高峰的大小没有差异。与对照组相比，注射睾酮的雄鼠到达繁殖准备开始的时间也更快，CP直径峰值也更大。睾酮抑制的鸟类没有表现出迁徙准备的迹象，只有微弱的CP直径增加。这些结果表明，在迁徙准备过程中，睾丸激素的早期升高可能会使雄性更早地离开非繁殖区，并到达更高级的繁殖区。该实验表明，候鸟的冬季到繁殖季节的结转效应可能有重要的生理基础。
SUMMARY The timing of events associated with spring migration can be an important determinant of fitness for migratory birds. The need to prepare and maintain physical condition for migration is one demand that must be met for early arrival on breeding areas, and this demand is compounded by the energetic demands of the physiological transition to breeding. Here, we examined whether migratory birds, specifically males, can adequately meet both of these demands by elevating the sex steroid testosterone early during migratory preparation. To test this, we used a captive experiment in which we photostimulated male dark-eyed juncos (Junco hyemalis) and manipulated circulating testosterone. We predicted males with elevated testosterone would prepare to migrate and breed faster than control males or males where the ability of testosterone to bind with receptors, or be converted to estradiol, was inhibited (testosterone inhibited). We measured migratory preparation using mass, food intake, fat deposits and nocturnal activity (Zugunruhe). To estimate breeding preparation, we measured the diameter of the cloacal protuberance (CP). We found that males in the testosterone treatment group began migratory preparation approximately 10 days before controls. There was no difference in the magnitude of peak migratory condition between testosterone-implanted birds and controls. Males implanted with testosterone also reached the onset of breeding preparation faster and had larger peak CP diameter compared with controls. Testosterone-inhibited birds showed no signs of migratory preparation and only a weak increase in CP diameter. These results demonstrate that early elevation of testosterone during migratory preparation could incur benefits for males in terms of the ability to depart earlier from non-breeding areas and arrive in a more advanced breeding condition. This experiment demonstrates that there may be important physiological underpinnings to known winter to breeding season carry-over effects in migratory birds.
影响因子：
4.8
作者：
Inger, Richard;Harrison, Xavier A.;Bearhop, Stuart
通讯作者：
Bearhop, Stuart
影响因子：
4.8
作者：
Gunnarsson, Tomas G.;Gill, Jennifer A.;Sutherland, William J.
通讯作者：
Sutherland, William J.