Data from: Sexual conflict over mating in Gnatocerus cornutus? Females prefer lovers not fighters

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.雌性配偶选择与雄性间竞争是性选择的两类典型作用机制。然而这两种机制并非总是青睐同一类雄性。此外，近期研究表明，雌性配偶选择有时会使那些降低雌性适合度的雄性获得演化收益。因此，雄性间竞争与雌性配偶选择究竟是青睐同一类雄性还是不同类雄性，以及雌性能否从配偶选择中获益，仍是悬而未决的科学问题。在角甲虫（Gnatocerus cornutus）中，雄性具有特化膨大的上颚用于对抗竞争对手；在直接争夺配偶的雄性间竞争场景下，上颚体积更大的雄性可获得交配优势。但目前尚不明确雌性是否偏好这类竞争力较强的雄性。本研究发现，雌性的配偶选择更青睐雄性的求偶行为而非上颚大小，且这两个性状在表型与遗传层面均无相关性。与具有吸引力、求偶行为旺盛的雄性交配，可使雌性获得间接收益，但该收益仅依赖于雄性吸引力的可遗传特性。与具吸引力的雄性交配，则可规避因与竞争力强的雄性交配而对雌性后代产生的间接代价。本研究结果表明，雄性间竞争可能会限制雌性的配偶选择，进而有可能降低雌性适合度，并引发交配过程中的性冲突。