Condition-dependent female chemical signals and adaptive male mate choice in the sexually cannibalistic spider Argiope bruennichi

信息素是一种化学物质，可以在物种内的个体之间传递信息。特别是在节肢动物中，化学信号是普遍的交流手段，特别是在性交流中。男性信息素在女性配偶选择的背景下得到了很好的研究。然而，同样普遍发生的基于女性化学线索的男性配偶选择直到最近才被承认，理解女性性信号的演变和适应性男性伴侣选择决定的标准是性选择研究的最后一个空白之一。一般来说，只有当(1)选择的收益大于成本，(2)当雌性的质量不同时，雄性挑剔的进化和交配策略的有条件调整才是有利的。这两个条件在球网蜘蛛Argiope Bruennichi中都得到了满足。这一物种的雄性交配率非常低，因此与低质量的雌性交配对一生的繁殖成功至关重要。此外，雌性在繁殖力上也有很大的差异。行为分析表明，雄性根据雌性的交配状态、年龄和大小来调整他们的交配行为，它们很可能是通过化学线索进行评估的。因此，作为对蜘蛛这一目的的首次研究，我们建议将化学生态分析和行为分析相结合，以拓宽我们对雌性性信号的条件和状态依赖的变异及其在雄性配偶选择中的作用的认识。我们假设雌性斑潜蝇的化学图谱包含条件依赖的信息，雄性利用雌性的化学图谱的变异来做出适应性的交配决定。具体地说，这个项目将调查(1)基于雌性化学线索的变化的男性配偶选择，(2)不稳定的雌性线索在配偶评估中的作用，以及(3)雌性是否可以调整其信号传递努力，以最大化其健康回报。

Pheromones are chemical substances that transmit information between individuals within a species. Particularly in arthropods, chemical signals are the prevalent means of communication, especially in sexual communication. Male pheromones in the context of female mate choice are well studied. Yet, the likewise widespread occurrence of male mate choice based on female chemical cues has only recently been acknowledged and understanding the evolution of female sexual signals and the criteria underlying adaptive male mate choice decisions is one of the last blank spots of sexual selection research. Generally, the evolution of male choosiness and the conditional adjustment of mating tactics are favored only if (1) the benefits of choosing exceed the costs and (2) when females vary in quality. Both conditions are met in the orb-web spider Argiope bruennichi. Males of this species have very low mating rates, hence mating with low-quality females critically affects life-time reproductive success. Moreover, females vary considerably in fecundity. Behavioral assays show that males adjust their mating behavior depending on female mating status, age and size, which they most likely assess via chemical cues. Therefore, as the first study to this aim in spiders, we propose to combine chemical-ecological analyses and behavioral assays on A. bruennichi to broaden our knowledge on condition- and state-dependent variation of female sexual signals and their function in male mate choice. We hypothesize that the chemical profiles of female A. bruennichi contain condition-dependent information and that males use variation in the chemical profiles of females to make adaptive mating decisions. Specifically, this project will investigate (1) male mate choice based on variation in female chemical cues, (2) the role of volatile female cues in mate assessment, and (3) whether females can adjust their signaling effort to maximize their fitness returns.