Kim Sin-Yeon, Velando Alberto
Departamento de Ecoloxía e Bioloxía Animal, Universidade de Vigo, Vigo, 36310, Spain.
BMC Evol Biol. 2016 Feb 29;16:52. doi: 10.1186/s12862-016-0613-4.
Secondary sexual traits and mating preferences may evolve in part because the offspring of attractive males inherit attractiveness and other genetically correlated traits such as fecundity and viability. A problem regarding these indirect genetic mechanisms is how sufficient genetic variation in the traits subject to sexual selection is maintained within a population. Here we explored the additive genetic correlations between carotenoid-based male ornament colouration, female fecundity and juvenile survival rate in the three-spined stickleback (Gasterosteus aculeatus) to test the possibility that attractiveness genes reduce important fitness components in the bearers not expressing the sexual trait.
Male sexual attractiveness (i.e., red nuptial colouration) as well as female fecundity and juvenile viability showed heritable variations in the three-spined stickleback. Thus, females can gain indirect benefits by mating with an attractive male. There was a strong positive genetic correlation between female fecundity and juvenile viability. However, red sexual signal of male sticklebacks was negatively genetically correlated with juvenile survival, suggesting genetic conflict between attractiveness and viability. There was no significant correlation between attractiveness of brothers and fecundity of sisters, suggesting no intra-locus sexual conflict.
The negative effects of mating with a colourful male on offspring viability may contribute to maintaining the heritable variation under strong directional sexual selection. The strength of indirect sexual selection may be weaker than previously thought due to the hidden genetic conflicts.
第二性征和交配偏好的进化可能部分是因为有魅力的雄性的后代继承了魅力以及其他与之基因相关的特征，如繁殖力和生存能力。关于这些间接遗传机制的一个问题是，在一个种群中，受性选择影响的性状如何保持足够的遗传变异。在这里，我们探究了三刺鱼（Gasterosteus aculeatus）中基于类胡萝卜素的雄性饰羽颜色、雌性繁殖力和幼鱼存活率之间的加性遗传相关性，以检验魅力基因是否会降低未表现出该性征的个体的重要适合度成分的可能性。
在三刺鱼中，雄性的性魅力（即红色婚羽颜色）以及雌性繁殖力和幼鱼生存能力都表现出可遗传的变异。因此，雌性通过与有魅力的雄性交配可以获得间接益处。雌性繁殖力和幼鱼生存能力之间存在很强的正遗传相关性。然而，雄性三刺鱼的红色性信号与幼鱼存活率呈负遗传相关，这表明在魅力和生存能力之间存在遗传冲突。兄弟的魅力与姐妹的繁殖力之间没有显著相关性，这表明不存在基因座内的性冲突。
与色彩鲜艳的雄性交配对后代生存能力产生的负面影响，可能有助于在强烈的定向性选择下维持可遗传变异。由于隐藏的遗传冲突，间接性选择的强度可能比之前认为的要弱。
