Energetics of Mammalian Reproduction and Life History

[309994] Kenagy将对自1984年以来一直在研究的金毛地松鼠种群进行生殖能量消耗、身体状况和繁殖成功之间的关系调查。提出的研究的生理维度侧重于自然条件下的密集生理表现——最大产量和最大工作量，以及随之而来的能量需求。这方面的两个典型例子是发生在哺乳期雌性的亲代生产支出的高峰以及发生在雄性的与交配，攻击和防御相关的行为支出的高峰。在研究的每个方面，性能都是通过近端能量平衡及其表型变异来量化的，然后通过人口统计学，即生存和未来繁殖来评估最终的成功。将研究每日能量消耗的直接关系，以及体重和生存条件的中间关系，认识到生殖表现可能在一个种群的所有成员的类似峰值水平上运行，并且由此产生的生殖输出是个体优化的。在自由生活的动物中，我们使用稳定同位素测量能量消耗，并通过全身电导率测量身体状况（脂肪与瘦肉成分）。雌性繁殖、摄入和消耗的上限将通过实验操纵母体食物供应来研究。通过无线电遥测冬眠松鼠的冬眠模式来评估越冬能量平衡。将根据能量平衡和能量供应的实验操作来评价一岁雄性的灵活性和可变生殖成熟度。这项研究将有助于对种群中个体的生理和行为变化如何在生命史过程中转化为生存和繁殖成功的表达的综合理解。＊＊＊

9309994 Kenagy The relationship between reproductive energy expenditures, body condition and reproductive success will be investigated in a population of golden-mantled ground squirrels that has been under study since 1984. The physiological dimension of the proposed research focuses on intensive physiological performances under natural conditions -- maximal production and maximal work load, and the accompanying demand for energy. Two model cases of this are the peak parental production expenditures that occur in lactating females and the peak behavior expenditures that occur in males associated with mating, aggression and defense. In each aspect of the study, performances are quantified in terms of proximal energy balance and its phenotypic variation, and then the ultimate success will be evaluated in terms of demography, i.e., survival and future reproduction. The direct relationship of daily energy expenditure, and the intermediary relationship of body mass and condition to survival will be examined, recognizing that reproductive performances may operate at similar peak levels for all members of a population and that the resulting reproductive output is individually optimized. In freeliving animals we measure energy expenditure using stable isotopes, and body condition (fat vs. lean components) by total body electrical conductivity. The upper limits of female reproduction, intake and expenditure will be investigated by experimentally manipulating maternal food supply. Overwinter energy balance will be evaluated by radiotelemetry of torpor patterns in hibernating squirrels. Flexibility and variable reproductive maturity in yearling males will be evaluated in terms of energy balance and an experimental manipulation of energy supply. This research should contribute to an integrated understanding of how variation in the physiology and behavior of individuals in a population translates into the expression of survival and reproductive success over the cou rse of life history. ***