Data from: Conspicuous female ornamentation and tests of male mate preference in threespine sticklebacks (Gasterosteus aculeatus)

Sexual selection drives the evolution of exaggerated male ornaments in many animal species. Female ornamentation is now acknowledged also to be common but is generally less well understood. One example is the recently documented red female throat coloration in some threespine stickleback (Gasterosteus aculeatus) populations. Although female sticklebacks often exhibit a preference for red male throat coloration, the possibility of sexual selection on female coloration has been little studied. Using sequential and simultaneous mate choice trials, we examined male mate preferences for female throat color, as well as pelvic spine color and standard length, using wild-captured threespine sticklebacks from the Little Campbell River, British Columbia. In a multivariate analysis, we found no evidence for a population-level mate preference in males, suggesting the absence of directional sexual selection on these traits arising from male mate choice. Significant variation was detected among males in their preference functions, but this appeared to arise from differences in their mean responsiveness across mating trials and not from variation in the strength (i.e., slope) of their preference, suggesting the absence of individual-level preferences as well. When presented with conspecific intruder males, male response decreased as intruder red throat coloration increased, suggesting that males can discriminate color and other aspects of phenotype in our experiment and that males may use these traits in intrasexual interactions. The results presented here are the first to explicitly address male preference for female throat color in threespine sticklebacks.

性选择推动了诸多动物类群中夸张型雄性装饰性状的演化。如今雌性装饰性状虽已被证实普遍存在，但相关研究整体仍较为匮乏。其中一个典型案例便是近期在部分三刺棘鱼（Gasterosteus aculeatus）种群中记录到的雌性喉部红色着色现象。尽管雌性三刺棘鱼通常会偏好具有红色喉部着色的雄性，但针对雌性体色所受性选择的相关研究却极少开展。本研究以采自加拿大不列颠哥伦比亚省小金坎贝尔河的野生三刺棘鱼为实验对象，通过顺序性与同时性择偶试验，探究雄性对雌性喉部着色、骨盆棘着色以及标准体长的择偶偏好。经多变量分析，我们未发现雄性存在种群水平择偶偏好的证据，这表明雄性择偶选择并未对上述性状产生定向性选择压力。研究还发现不同雄性间的偏好函数存在显著差异，但该差异源于各雄性在交配试验中的平均响应程度不同，而非偏好强度（即斜率）的变化，由此可见雄性同样不存在个体水平的择偶偏好。当雄性遭遇同种雄性入侵者时，其攻击响应会随入侵者喉部红色着色程度的升高而减弱，这表明本实验中雄性能够区分体色与其他表型特征，且雄性可能在种内同性竞争中利用此类性状。本研究结果首次明确探究了三刺棘鱼雄性对雌性喉部着色的择偶偏好。