Behavioral, energetic, and color trait integration in guppies: testing the melanocortin hypothesis

Individuals of the same population differ consistently from each other in the average expression of behavioral and physiological traits. Often, such traits are integrated and thus correlated with each other. However, the underlying proximate mechanisms generating and maintaining this among-individual covariation are still poorly understood. The melanocortin hypothesis suggests that the melanocortin pathway can have pleiotropic effects linking the expression of melanin-based coloration with physiological and behavioral traits. In the present study, we test this hypothesis in adult male guppies (Poecilia reticulata), by estimating among individual correlations between behaviors (activity, feeding, boldness, display and chase during courtship), stress response (peak metabolic rate), and coloration (black spot, fuzzy black, orange). The lack of correlation of any behavior or metabolism with black coloration indicates that the melanocortin hypothesis is not supported in this species. However...同一种群内的个体在行为与生理性状的平均表达水平上始终存在差异。这类性状通常会发生整合并彼此相关联。然而，驱动并维持这种个体间协变关系的近端机制仍未得到充分阐释。黑皮质素假说（melanocortin hypothesis）提出，黑皮质素通路可产生多效性效应，将基于黑色素的体色表达与生理及行为性状联系起来。本研究以成年雄性孔雀鱼（Poecilia reticulata）为研究对象，通过估算不同行为（活动水平、摄食行为、大胆性、求偶期间的展示与追逐行为）、应激反应（峰值代谢率）与体色性状（黑斑、模糊黑斑、橙色区域）之间的个体间相关性，对该假说进行检验。未发现任何行为或代谢指标与黑色体色存在相关性，这表明黑皮质素假说在该物种中并不成立。然而……