Thierry Anne-Mathilde, Ropert-Coudert Yan, Raclot Thierry
Université de Strasbourg, IPHC, 23 rue Becquerel, 67087 Strasbourg, France; CNRS, UMR7178, 67037 Strasbourg, France.
Conserv Physiol. 2013 May 14;1(1):cot007. doi: 10.1093/conphys/cot007. eCollection 2013.
Study of physiological mechanisms can help us to understand how animals respond to changing environmental conditions. In particular, stress hormones (i.e. glucocorticoids, such as corticosterone) are described as mediating resource allocation, allowing animals to adjust their physiology and behaviour to predictable and unpredictable changes in the environment. In this study, we investigated the effects of an experimental increase in baseline corticosterone levels on the breeding effort and the reproductive output of chick-rearing male Adélie penguins (Pygoscelis adeliae). The number of chicks per nest, their body mass, and their size were monitored throughout the study. Direct observations allowed measurement of the time spent foraging at sea and caring for the young on the nest. At the end of the treatment, blood samples were collected for isotope analysis. Although all birds raised at least one chick, reproductive output was decreased by 42% in corticosterone-treated birds compared with control birds. The increase in corticosterone levels during the guard stage did not affect the mass of surviving chicks or the brood mass at fledging. Corticosterone-treated males spent on average 21% more time at the nest than control birds. However, the duration of foraging trips was similar between both groups. In addition, the similarity of isotopic signatures suggests that both groups foraged at similar locations and ingested the same prey species. The detailed on-land behaviour of birds should be examined in further studies to clarify the possible links between corticosterone levels, brooding time, and reproductive output. Understanding the relationships between glucocorticoids, fitness, and ultimately population dynamics is fundamental to enabling conservation physiology as a discipline to be successful in helping to manage species of conservation concern.
对生理机制的研究有助于我们了解动物如何应对不断变化的环境条件。特别是，应激激素（即糖皮质激素，如皮质酮）被认为在介导资源分配，使动物能够根据环境中可预测和不可预测的变化来调整其生理和行为。在本研究中，我们调查了实验性提高基线皮质酮水平对育雏期阿德利企鹅（Pygoscelis adeliae）雄鸟的繁殖投入和繁殖产出的影响。在整个研究过程中，监测了每个巢穴中雏鸟的数量、体重和体型。通过直接观察来测量在海上觅食和在巢穴中照顾幼雏所花费的时间。在处理结束时，采集血样进行同位素分析。尽管所有鸟类至少养育了一只雏鸟，但与对照鸟类相比，接受皮质酮处理的鸟类的繁殖产出下降了42%。警戒期皮质酮水平的升高并未影响存活雏鸟的体重或出飞时的育雏群体体重。接受皮质酮处理的雄鸟在巢穴中的平均停留时间比对照鸟类多21%。然而，两组的觅食行程持续时间相似。此外，同位素特征的相似性表明两组在相似的地点觅食并摄取相同的猎物种类。鸟类在陆地上的详细行为应在进一步研究中进行检查，以阐明皮质酮水平、育雏时间和繁殖产出之间可能的联系。了解糖皮质激素、适应性以及最终种群动态之间的关系，对于使保护生理学作为一门学科成功地帮助管理受保护关注的物种至关重要。
