Female mate choice based on multiple male traits and adaptive offspring manipulation

本研究以日本冲绳县的野生孔雀鱼为研究对象，探讨了雌性在每一雄性特征的基础上选择配偶的收益和成本，以及雌性根据配偶对后代的适应性操纵。得到了以下结果：通过使用数字修改的视频回放刺激男性图像，证实了女性对男性橙色斑点的色彩饱和度的显著偏好。此外，观察结果表明，橙色斑点颜色饱和度高的雄性具有更强的采藻能力。亲代回归分析表明，雄孔雀鱼的采藻能力是一个遗传因素。采藻能力强的雄藻生长快，桔黄色斑点大。这些结果表明，雌性在雄性橙色斑点的基础上进行择偶，可以获得间接利益，如产生具有高觅食能力的后代，从而获得更大的繁殖成功率。据报道，雌孔雀鱼对总长度较大的雄孔雀鱼表现出择偶偏好，但也有一些雄孔雀鱼会拉长尾巴（尾鳍）以获得总长度较大的雄孔雀鱼。在水族实验中，一条雌鱼与两条长度相同但尾长不同的雄鱼身体接触，结果表明雌鱼对短尾雄鱼的偏好高于长尾雄鱼。雌性与长尾雄性交配需要付出代价，比如它们的后代体型小，繁殖效率低。然而，当雌性与长尾雄性交配时，为了降低与长尾雄性交配的成本，雌性会减少后代的数量，并使后代的性别比例偏向雄性。另一方面，雄性的长尾影响了它们的游泳表现，从而限制了它们对野生水域流速较慢的栖息地的选择。

This study aimed to examine the benefits and costs of female mate choice on the basis of each male trait and adaptive offspring manipulation by females depending on their mates using feral guppies Poecilia reticulata in Okinawa, Japan. The following results were obtained.1. By using digitally modified video playbacks of stimulus male images, a significant female preference for the color saturation of male orange spots was confirmed. In addition, observations indicated that males possessing the high color saturation of orange spots exhibited a greater algal-foraging ability. Parent-offspring regression analysis demonstrated that the algal-foraging ability of male guppies was a heritable component. Males possessing higher algal-foraging ability exhibited faster growth and larger orange spots. These results suggest that females can acquire indirect benefits such as producing offspring possessing the high algal-foraging ability and thus a greater reproductive success via their mate choice on the basis of male orange spot coloration.2. It has been reported that female guppies exhibited mate preference for males possessing large total lengths, however some males elongated their tails (caudal fins) to achieve large total lengths. Aquarium experiments in which a female physically contacted with two males exhibiting same total lengths but possessing different tail lengths indicated that the females preferred the short-tailed males over the long-tailed males. Females incurred costs of mating with long-tailed males, such as small body sizes and low reproductive efficiency of their daughters. However, when females mated with long-tailed males, they decreased the number of offspring and biased offspring sex ratio toward males in order to reduce the costs of mating with the long-tailed males. On the other hand, long tails of males affected their swimming performance and consequently limited their choice of habitats to those with slow water velocity in the wild.