Melanin in a changing world: brown trout coloration reflects alternative reproductive strategies in variable environments

Melanins are the most widespread pigments in animals but their adaptive significance remains elusive. Recent studies suggest that intraspecific variation in melanin-based coloration reflects individual genetic-based alternative strategies to cope with environment variability, which could be crucial for their responses to climate changes. However, empirical evidence is still scarce. In this study, we tested how skin coloration in natural populations of brown trout Salmo trutta fario would reflect alternative reproductive strategies in different environments. We experimentally manipulated the flow regime (constant vs. variable) in artificial streams and compared the reproductive investment (body mass and plasma triglyceride variations), innate immunity (variations in plasma peroxidase and lysozyme activity) and reproductive success (number of mates and offspring) of differently colored brown trout over 2 reproductive seasons. Results show that darker males had a higher reproductive invest...

黑色素（melanins）是动物界分布最为广泛的色素之一，但其适应性意义至今仍难以阐明。近期研究表明，基于黑色素的体色种内变异，反映了个体基于遗传的差异化环境适应策略，这类策略可能对动物应对气候变化至关重要。然而，相关实证证据仍较为匮乏。本研究旨在探究褐鳟（Salmo trutta fario）自然种群的体表体色如何反映不同环境下的差异化繁殖策略。我们通过人工溪流操控水流模式（恒定 vs. 可变），在两个繁殖季内，对比了不同体色褐鳟的繁殖投入（体质量与血浆甘油三酯（plasma triglyceride）水平变化）、先天免疫能力（血浆过氧化物酶（peroxidase）与溶菌酶（lysozyme）活性变化）以及繁殖成功率（交配对象数量与后代数量）。研究结果显示，体色更深的雄性个体具有更高的繁殖投入……