Relative costs and benefits of alternative reproductive phenotypes at different temperatures - genotype-by-environment interactions in a sexually selected trait

Background: The maintenance of considerable genetic variation in sexually selected traits (SSTs) is puzzling given directional selection expected to act on these traits. A possible explanation is the existence of a genotype-by-environment (GxE) interaction for fitness, by which elaborate SSTs are favored in some environments but selected against in others. In the current study, we look for such interactions for fitness-related traits in the bulb mite, a male-dimorphic species with discontinuous expression of a heritable SST in the form of enlarged legs that are used as weapons. Results: We show that evolution at 18°C resulted in populations with a higher prevalence of this SST compared to evolution at 24°C. We further demonstrate that temperature modified male reproductive success in a way that was consistent with these changes. There was a genotype-by-environment interaction for reproductive success - at 18°C the relative reproductive success of armored males competing with unarmored o...研究背景：性选择性状（Sexually Selected Traits, SSTs）通常会面临定向选择，但这类性状却能维持大量的遗传变异，这一现象长期以来令学界困惑。一种潜在的解释是，适合度（Fitness）存在基因型-环境（Genotype-by-Environment, GxE）互作：即结构精致的性选择性状在部分环境中会受到正向选择，而在另一类环境中则会遭到负向选择。本研究以球茎螨（Bulb Mite）为研究对象，该物种为雄性二态型类群，其可遗传的性选择性状以作为争斗武器的膨大附肢形式呈现，且该性状的表达存在不连续性。我们在此类群中探寻适合度相关性状的基因型-环境互作现象。研究结果：本研究证实，在18℃条件下经过多代演化的种群，其性选择性状的发生率显著高于24℃演化组。本研究进一步发现，温度对雄性繁殖成功率的调控效应与上述演化结果高度一致。繁殖成功率存在显著的基因型-环境互作：在18℃条件下，与无装甲雄性竞争时，具装甲雄性的相对繁殖成功率……