The transfer of male cuticular hydrocarbons provides a reliable cue of the risk and intensity of sperm competition in decorated crickets

Theoretically, males should increase their ejaculate expenditure when the probability of sperm competition occurring (or risk) is high but decrease ejaculate expenditure as the number of competing ejaculates (or intensity) increases. Here we examine whether male decorated crickets (Gryllodes sigillatus) use cuticular hydrocarbons (CHCs) transferred to females by rival males at mating to assess the risk and intensity of sperm competition and adjust their ejaculate accordingly. Unmated females and those perfumed with CHCs extracted from one, three or five males could be distinguished chemically, providing a reliable cue of the risk and intensity of sperm competition. In agreement with theory, males mating to these females increased sperm number with the risk of sperm competition and decreased sperm number with the intensity of sperm competition. Similarly, as the risk of sperm competition increased, males produced a larger and more attractive spermatophylax (an important non-sperm compone..., In Experiment 1, we collected the cuticular hydrocarbon (CHC) profiles of virgin females that had been perfumed with the CHCs of one male, three males and five males, as well as virgin males and virgin females that were not perfumed. We determined the CHC of crickets in these treatments using established GC-MS protocols for this species (Gryllodes sigillatus). This experiment showed that the CHC profile of crickets in these treatments could be statistically distinguished and therefore provide a reliable cue for the risk and intensity of sperm competition.
In Experiment 2, we applied these same perfuming treatments to females (virgin female - control, one male, three males and five males) and then allowed them to mate with a naive virgin male. We measured each males sperm count using microscopy. We also measure the dry weight of the spermatophylax (using an electronic balance) and the attractiveness of the spermatophylax based on the free amino acid composition. We determined the free am..., , # The transfer of male cuticular hydrocarbons provides a reliable cue of the risk and intensity of sperm competition in decorated crickets
This publications consists of two experiments. In Experiment 1, we perfumed virgin females with the cuticular hydrocarbons (CHCs) of one male, three males, five males and measured their CHC profile using GC-MS. We also measured CHCs in a sample of virgin males and virgin females. We used discriminant function analysis to show that the CHC profile of crickets in these treatment groups could be statistically distinguished and therefore provide a male cricket with information on the risk and intensity of sperm competition. In Experiment 2, we applied these same perfuming procedures (no perfuming - control, one male, three males and five males) to virgin females and then allowed them to mate to a naive and virgin male. For each male, we measure their sperm count (using microscopy), dry weight of the spermatophylax (using an electronic balance) and the mu...

从理论层面而言，当精子竞争（sperm competition）发生概率（即竞争风险）较高时，雄性应提升其射精投入；而随着竞争性射精的数量（即竞争强度）增加，雄性则需降低射精投入。本研究旨在探究装饰蟋蟀（Gryllodes sigillatus）是否会借助交配时由同性竞争对手转移至雌性体内的表皮碳氢化合物（cuticular hydrocarbons, CHCs），以此评估精子竞争的风险与强度，并据此调整射精行为。
未交配雌性，以及经取自1只、3只或5只雄性的CHCs处理的雌性，均可通过化学方法区分，这为精子竞争的风险与强度提供了可靠的信号。与理论预期一致，与这类雌性交配的雄性，其精子数量随精子竞争风险升高而增加，随竞争强度升高而减少。此外，随着精子竞争风险提升，雄性产出的精护囊（spermatophylax，一种重要的非精子组分……）体积更大、吸引力更强。
在实验1中，我们收集了经1只、3只、5只雄性CHCs处理的处女雌性，以及未处理的处女雄性与处女雌性的表皮碳氢化合物谱图。我们采用针对该物种（Gryllodes sigillatus）的标准气相色谱-质谱联用（gas chromatography-mass spectrometry, GC-MS）实验方案，分析了不同处理组蟋蟀的CHCs。结果显示，不同处理组蟋蟀的CHC谱图可通过统计学方法区分，因此可作为雄性蟋蟀评估精子竞争风险与强度的可靠信号。
在实验2中，我们对雌性（处女雌性——对照组、经1只、3只、5只雄性CHCs处理组）施加相同处理后，让其与未经历交配的处女雄性交配。我们通过显微镜计数法测定了每只雄性的精子数量；同时利用电子天平称量精护囊的干重，并基于游离氨基酸组成评估精护囊的吸引力。我们对游离氨基酸……
# 雄性表皮碳氢化合物的转移为装饰蟋蟀的精子竞争风险与强度提供可靠信号
本研究包含两项实验。在实验1中，我们利用1只、3只、5只雄性的表皮碳氢化合物（CHCs）处理处女雌性，并通过GC-MS测定其CHC谱图；同时我们也测定了处女雄性与处女雌性的CHCs含量。我们采用判别函数分析（discriminant function analysis）证实，不同处理组蟋蟀的CHC谱图可通过统计学方法区分，因此能够为雄性蟋蟀提供精子竞争风险与强度的相关信息。在实验2中，我们对处女雌性施加相同的处理（未处理——对照组、经1只、3只、5只雄性CHCs处理组），随后让其与未经历交配的处女雄性交配。针对每只雄性，我们测定了其精子数量（显微镜计数法）、精护囊干重（电子天平称量）以及……