Okada Kensuke, Katsuki Masako, Sharma Manmohan D, House Clarissa M, Hosken David J
Graduate School of Environmental Science, Okayama University, , Tsushima-naka 1-1-1, Okayama 700-8530, Japan, Faculty of Life and Environmental Sciences, University of Tsukuba, , Tennoudai 1-1-1, Tsukuba 305-8572, Japan, Centre for Conservation and Ecology, College of Life and Environmental Sciences, University of Exeter, , Tremough, Penryn TR109EZ, UK.
Proc Biol Sci. 2014 May 7;281(1785):20140281. doi: 10.1098/rspb.2014.0281. Print 2014 Jun 22.
Female mate choice and male-male competition are the typical mechanisms of sexual selection. However, these two mechanisms do not always favour the same males. Furthermore, it has recently become clear that female choice can sometimes benefit males that reduce female fitness. So whether male-male competition and female choice favour the same or different males, and whether or not females benefit from mate choice, remain open questions. In the horned beetle, Gnatocerus cornutus, males have enlarged mandibles used to fight rivals, and larger mandibles provide a mating advantage when there is direct male-male competition for mates. However, it is not clear whether females prefer these highly competitive males. Here, we show that female choice targets male courtship rather than mandible size, and these two characters are not phenotypically or genetically correlated. Mating with attractive, highly courting males provided indirect benefits to females but only via the heritability of male attractiveness. However, mating with attractive males avoids the indirect costs to daughters that are generated by mating with competitive males. Our results suggest that male-male competition may constrain female mate choice, possibly reducing female fitness and generating sexual conflict over mating.
雌性配偶选择和雄性间竞争是性选择的典型机制。然而，这两种机制并不总是青睐同一批雄性。此外，最近有一点变得很清楚，即雌性选择有时会使那些降低雌性适应性的雄性受益。所以，雄性间竞争和雌性选择是青睐同一批还是不同批雄性，以及雌性是否能从配偶选择中受益，这些问题仍然没有答案。在有角甲虫角蠊中，雄性具有增大的下颚用于与对手争斗，在雄性为争夺配偶直接竞争时，更大的下颚会带来交配优势。然而，尚不清楚雌性是否更喜欢这些极具竞争力的雄性。在此，我们表明雌性选择针对的是雄性求偶行为而非下颚大小，并且这两个特征在表型或基因上并无关联。与有吸引力、求偶积极性高的雄性交配会给雌性带来间接益处，但这仅通过雄性吸引力的遗传性来实现。然而，与有吸引力的雄性交配可避免雌性与有竞争力的雄性交配给女儿带来的间接成本。我们的研究结果表明，雄性间竞争可能会限制雌性的配偶选择，这可能会降低雌性适应性并引发交配方面的性冲突。
