School of Earth and Environmental Sciences, University of Manchester, United Kingdom.
Evolutionary Ecology Unit, Department of Biology, Lund University, Sweden.
Evolution. 2018 Apr;72(4):906-915. doi: 10.1111/evo.13457. Epub 2018 Mar 14.
Sexual conflict is a pervasive evolutionary force that can reduce female fitness. Experimental evolution studies in the laboratory might overestimate the importance of sexual conflict because the ecological conditions in such settings typically include only a single species. Here, we experimentally manipulated conspecific male density (high or low) and species composition (sympatric or allopatric) to investigate how ecological conditions affect female survival in a sexually dimorphic insect, the banded demoiselle (Calopteryx splendens). Female survival was strongly influenced by an interaction between male density and species composition. Specifically, at low conspecific male density, female survival increased in the presence of heterospecific males (C. virgo). Behavioral mating experiments showed that interspecific interference competition reduced conspecific male mating success with large females. These findings suggest that reproductive interference competition between con- and heterospecific males might indirectly facilitate female survival by reducing mating harassment from conspecific males. Hence, interspecific competitors can show contrasting effects on the two sexes thereby influencing sexual conflict dynamics. Our results call for incorporation of more ecological realism in sexual conflict research, particularly how local community context and reproductive interference competition between heterospecific males can affect female fitness.
性冲突是一种普遍存在的进化力量，它会降低雌性的适合度。实验室中的实验进化研究可能会高估性冲突的重要性，因为这种环境中的生态条件通常只包括一个单一的物种。在这里，我们通过实验操纵同种雄性密度（高或低）和物种组成（同域或异域）来研究生态条件如何影响两性异形昆虫——带斑裙凤蝶（Calopteryx splendens）的雌性存活率。雌性存活率受到雄性密度和物种组成之间相互作用的强烈影响。具体来说，在同种雄性密度较低的情况下，存在异性种雄性（C. virgo）时，雌性存活率会增加。行为交配实验表明，种间干扰竞争降低了同种大型雄性与雌性的交配成功率。这些发现表明，同种和异性雄性之间的繁殖干扰竞争可能通过减少同种雄性的交配骚扰，间接促进雌性的存活。因此，种间竞争者对两性可能会产生相反的影响，从而影响性冲突的动态。我们的研究结果呼吁在性冲突研究中纳入更多的生态现实，特别是异性雄性之间的局部群落背景和繁殖干扰竞争如何影响雌性的适合度。
