Much is known about the genetic variance in certain components of metabolism, most notably resting and maximum metabolic rate. This is in stark contrast to the lack of information on genetic variance in the metabolic rate of individuals that feed and express routine activity, and how this rate correlates with other components of the energy budget or life history traits. Here we quantify genetic variance in metabolic rate (MR) under such conditions, as well as food consumption, juvenile somatic growth rate and age at maturation under ad lib food availability in a set of 10 clones of Daphnia magna from a natural population. Broad sense evolvabilities (0.16–0.56%) were on the same order of magnitude as those typically observed for physiological and life history traits, and suggest that all these traits have the potential to evolve within this population. We did not find support for the previously hypothesized positive genetic correlation between metabolic rate and growth rate. Rather, the patterns of genetic correlations suggest that genetic variance in food consumption is the single most influential trait shaping somatic growth rate, but that additional variance in growth can be explained by considering the joint effect of consumption and MR. The genetic variance in consumption and MR also translated into genetic variance in age at maturation, creating a direct link between these energy budget components and a life history trait with strong fitness effects. Moreover, a weak positive correlation between MR and food consumption suggests the presence of substantial amounts of independent genetic control of these traits, consistent with results obtained using genomic approaches.

中文翻译：

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大型蚤（Daphnia magna）代谢率的遗传变异及其与其他能量收支和生活史的关系

关于代谢某些组成部分的遗传变异，人们最为了解，最显着的是静止和最大代谢率。这与喂养和表达日常活动的个体的代谢率缺乏遗传变异信息以及该速率与能量预算或生活史特征的其他组成部分如何形成鲜明对比。在这里，我们量化这样的条件下的代谢率（MR）在成熟下遗传变异，以及食物消耗，少年体细胞生长速率和年龄随意食物供应在一组的10个克隆水蚤来自自然人口。广义上的可进化性（0.16-0.56％）与生理和生活史特征通常观察到的数量级处于同一数量级，这表明所有这些特征都有可能在该种群中进化。我们没有发现支持以前假设的代谢率和生长率之间的正遗传相关性。相反，遗传相关性的模式表明，食物消费中的遗传差异是影响躯体生长速度的唯一最有影响力的性状，但是可以通过考虑食用和MR的共同影响来解释增长中的其他差异。消耗量和MR的遗传差异也转化为成熟时的年龄遗传差异，在这些能量预算组成部分和具有强大适应性的生活史特征之间建立直接联系。而且，MR和食物消耗之间的弱正相关表明存在大量独立的遗传控制这些特征，这与使用基因组方法获得的结果一致。