Female-limited colour polymorphism in the crab spider Synema globosum (Araneae: Thomisidae)

Conspicuous colour variation, caused by the influence of the environment on phenotype or by genetic differences among individuals, is frequently observed in nature. If genetic in origin, colour variation can facilitate the study of mechanisms that contribute to the maintenance of true polymorphisms. Here we describe, for the first time, the female-limited colour polymorphism in the crab spider, Synema globosum. We looked for associations between life-history traits and female colour morph, and identified potential agents of selection that could influence the maintenance of the polymorphism. Our results showed that the polymorphism is discrete and heritable, and that differences in colour among morphs are likely to be detectable by honeybees, birds, and conspecifics. We found limited evidence of differences among morphs in morphology and ecology, and found no differences in components of reproduction. Based on the lines of evidence obtained in this study, we suggest that selection exerted by prey, predators, and/or mates is likely to influence the maintenance of the polymorphism observed in S. globosum.

自然界中普遍存在由环境对表型的作用或个体间遗传差异所导致的显著体色变异。若体色变异由遗传因素引起，则可为探究维持稳定多态性的内在机制提供研究契机。我们首次报道了球腹蟹蛛（Synema globosum）的雌性限制型体色多态性（female-limited colour polymorphism）。本研究探究了生活史性状与雌性体色变型之间的关联，并鉴定出可能影响该多态性维持的潜在选择因子。研究结果显示，该多态性呈离散分布且可遗传，各体色变型间的色彩差异可被蜜蜂、鸟类及同种个体感知。我们仅发现少量证据表明不同变型在形态学与生态学特征上存在差异，且未观察到繁殖相关组分存在显著差异。基于本研究获得的多项证据，我们推测猎物、天敌及/或配偶所施加的选择作用，可能会对球腹蟹蛛（S. globosum）的体色多态性维持产生影响。