SGER: Reproductive Biology of Female King Penguins

大量证据表明，雌鸟可能对其后代的性别比例施加控制。在最佳条件下，雏鸡产蛋率较高；在恶劣的环境条件下，更多的年轻人是雄性。对此有几种合理的解释。在某些情况下，年轻的雄性分散，因此在压力条件下不会与父母或兄弟姐妹竞争。在其他栖息地条件有利的情况下，有新雏鸟的母亲得到年长的雌性后代的帮助，增加了繁殖成功率。在一窝产多枚蛋的物种中，可能会有雌雄同体的雏鸟，对父母状况的自我评估可能不那么重要。然而，其他物种，如企鹅，在每个繁殖季节只下一到两个蛋。在这种情况下，性别比例分配策略的应用要求女性必须非常有能力评估自己和伴侣的状况。这项探索性研究的小额拨款将调查王企鹅幼崽的性别比例与父母的状况，以确定雌性是否控制了幼崽的性别。性别决定将通过血液样本的DNA分析来完成，这是该项目在帝企鹅身上测试的一种新方法。量化亲代条件将通过几种标准方法完成，包括测量体型，寄生虫负荷和免疫能力。这项研究还将探索羽毛颜色是否像其他鸟类和鱼类一样，是企鹅身体状况的一个指标。羽毛的颜色来自于饮食中衍生的类胡萝卜素，可能是评估健康和适应性的有用代理。企鹅在它们所处的环境中是占统治地位的捕食者，像后代性别比例这样的基本种群参数的变化可能反映了气候或食物资源分布和丰富程度的变化。这项工作的结果将与法国南极计划的科学家合作进行，将更好地了解企鹅种群动态和环境生物反馈的复杂机制。

Considerable evidence has accumulated that female birds may exert control over the sex ratio of their offspring. Under optimal conditions, more female chicks are produced; and under poor environmental conditions, more of the young are males. There are several plausible explanations for this. In some cases, young males disperse and so under stressful conditions do not compete with parents or siblings. In other instances where habitat conditions are favorable, mothers with new chicks are assisted by older female offspring, increasing reproductive success. In species that lay clutches with multiple eggs, there can be chicks of both sexes and self-assessment of parent condition may not be as crucial. However, in other species such as penguins, only one or two eggs are laid during each breeding season. In this situation, the application of the strategy of sex ratio allocation requires that females must be very capable of assessing their condition and that of their mates. This Small Grant for Exploratory Research will investigate the sex ratio of king penguin chicks relative to the condition of the parents to determine if females are controlling the gender of chicks. Sex determination will be accomplished by DNA analyses of blood samples, a new method to be tested on king penguins in this project. Quantifying parental condition will be done by several standard methods, including measures of body size, parasite load, and immunocompetence. This study will also explore the possibility that plumage coloration is an indicator of condition in penguins as it is in other bird and fish species. Plumage color is from diet-derived carotenoids and may be a useful proxy for evaluating health and fitness. Penguins are dominant predators in their environment and shifts in a population parameter as fundamental as offspring sex ratio might reflect changes in climate or in distribution and abundance of food resources. The results of this work, which will be conducted in collaboration with scientists from the French Antarctic Program, will provide a better understanding of penguin population dynamics and the complex mechanisms of environmental biofeedback.