Fuel for the pace of life: baseline blood glucose concentration coevolves with life history traits in songbirds

1. It has been proposed that life histories have coevolved with a suite of physiological and behavioural adaptations, termed pace-of-life syndromes (POLS). Here, we hypothesise that basal concentration of blood glucose (G0), a major source of energy circulating in vertebrate blood, may constitute a key component of POLS. 2. To test this hypothesis, we measured G0 in 30 passerine species and tested its covariation with body mass and other life history traits. Importantly, body mass is a major life history determinant and, when its effect is controlled for, there may be no single fast-slow life history continuum in birds comprising both fecundity and lifespan. Hence, we used individual life history traits, rather than principal component analysis, to characterise life history variation in our analysis. 3. In support of G0 life history coevolution, we found G0 to be negatively correlated with body mass and positively with reproductive investment in a single clutch across 30 passerine speci...1. 有研究提出，生物生活史与一系列生理和行为适应性特征共同演化，这类特征被称为生命速率综合征（pace-of-life syndromes, POLS）。本研究假设，作为脊椎动物血液中主要循环能量来源的基础血糖浓度（basal concentration of blood glucose, G0），可能是生命速率综合征的关键组成部分。 2. 为验证该假设，我们对30种雀形目鸟类的G0进行了检测，并分析其与体重及其他生活史特征的共变异关系。值得注意的是，体重是影响生活史的核心决定因素，在控制体重效应后，鸟类中可能并不存在同时涵盖繁殖力与寿命的单一快慢生活史连续体。因此，本研究未采用主成分分析，而是直接使用单个生活史特征来表征分析中的生活史变异。 3. 为支持血糖浓度与生活史共同演化的观点，我们发现，在30种雀形目鸟类中，G0与体重呈负相关，而与单次繁殖的繁殖投入呈正相关。