PRF/J: The Evolution of Metabolic Rate in Response to Temperature

温度对变温动物代谢率的影响的种间比较长期以来一直被用作生理适应环境的首要例子——通常来自相对寒冷栖息地的种群在低体温下进化出了更高的代谢能力（补偿）。种间比较提供了长期进化模式的观点，但对当代生理进化动力学的见解很少。当代种群的代谢进化动力学将通过对黑腹果蝇代谢率热依赖性的一系列补充研究来探索。首先，将对该物种的复制种群进行比较。其次，这些结果将与沿着3000公里样带收集的标本的相同类型数据进行比较。如果发生了代偿性进化，那么在低温（或高纬度）环境下进化的果蝇，相对于在高温环境下进化的果蝇，预计会表现出更高的代谢率。代谢率对极端温度选择的热依赖性的相关响应也将被研究。如果在温度代谢反应的组成部分之间存在遗传相关性，那么选择对极端温度的耐受性应该会影响其他温度下的代谢率。变温动物的代谢率对运动表现、竞争能力有着深远的意义，并与一系列生活史变量密切相关。最近在比较生理学和进化生理学方面的工作反复强调理解热敏性进化的重要性，但很少有研究在小型变温动物中检查这一特征。研究比较生理学的一个重要目标是确定为什么存在生命史参数之间的权衡（例如，生长速度和渐近大小之间的权衡）。最终，这样的研究对理解人类生命历史特征的生物学极限，如寿命和生殖寿命，具有重要意义。

Interspecific comparisons of temperature effects on metabolic rates of ectotherms have long been used as premier examples of physiological adaptation to environment - - typically populations from relatively cold habitats have evolved increased metabolic capacities (compensation) at low body temperatures. Interspecific comparisons provide a perspective on long term evolutionary patterns, but little insight into contemporary dynamics of physiological evolution. The dynamics of metabolic evolution in contemporary populations will be explored using a series of complementary studies of the thermal dependence of metabolic rate in Drosophila melanogaster. First, replicate stocks of the species will be compared. Second, these results will be compared to the same type of data from specimens collected along a 3000 kilometer transect. If compensatory evolution has occurred, flies evolving at low temperatures (or high latitudes) are expected to exhibit elevated metabolic rates relative to flies from high temperature situations. Correlated responses of thermal dependence of metabolic rate to selection for temperature extremes will also be examined. If there are genetic correlations between components of the metabolic response to temperature, selection for tolerance of temperature extremes should influence metabolic rate at other temperatures. %%% Metabolic rate in ectotherms has a profound significance for locomotor performance, competitive ability, and is strongly correlated with an array of life history variables. Recent work in comparative and evolutionary physiology repeatedly stresses the importance of understanding the evolution of thermal sensitivity, but few studies have examined this feature in small ectotherms. One important goal of studying comparative physiology is to ascertain why tradeoffs between life history parameters (for example, the tradeoff between growth rate and asymptotic size) exist. Ultimately such research has implications for understanding the biological limits of human life history traits such as longevity and reproductive life span.