Data from: Male genital titillators and the intensity of postcopulatory sexual selection across bushcrickets

Animal genitalia are diverse and a growing body of evidence suggests that they evolve rapidly under post-copulatory sexual selection. This process is predicted to be more intense in polyandrous species, although there have been very few comparative studies of the relationship between the complexity of genital structures in males and measures of the degree of polyandry. In some bushcricket families, males possess sclerotised copulatory structures known as titillators, which are inserted into the female’s genital chamber and moved rhythmically. Like other genital structures, bushcricket titillators are widely used as important taxonomic characters and show considerable variation across species in structure, shape and the extent to which they are spined. Here, we examine relationships between the presence/absence of titillators, titillator complexity and both mating frequency and the degree of polyandry in bushcrickets, using phylogenetic comparative analyses. Using published sources combined with original observations, data were obtained for the mean level of polyandry, the duration of the male and female sexual refractory periods and the level of complexity of titillators. To analyse data, we fitted phylogenetic generalised least squares models. No significant relationships were found between titillator presence or complexity and either the level of polyandry, duration of the male’s sexual refractory period or the ratio of the female and male sexual refractory periods. The duration of the female’s refractory period, however, was positively associated with titillator presence and negatively associated with titillator complexity. The data therefore partially support the hypothesis that post-copulatory sexual selection drives genital evolution in this taxon.动物生殖器（animal genitalia）具有丰富多样性，且越来越多的实证研究表明，其在交配后性选择（post-copulatory sexual selection）作用下会快速演化。据推测，该演化过程在多配物种（polyandrous species）中更为强烈，但目前针对雄性生殖器结构复杂程度与多配程度之间关联的比较研究仍极为稀缺。在部分螽斯（bushcricket）科类群中，雄性拥有一类被称为挑逗器（titillators）的硬化交配结构，该结构会插入雌性生殖腔并进行节律性运动。与其他生殖器结构类似，螽斯挑逗器被广泛用作重要的分类学特征（taxonomic characters），且在不同物种间，其结构、形态以及棘刺分布程度均存在显著差异。本研究借助系统发育比较分析（phylogenetic comparative analyses），探究了螽斯挑逗器的存在与否、复杂程度与交配频率及多配程度之间的关联。研究结合已发表文献与原始观测数据，获取了螽斯的平均多配水平、雌雄个体的性不应期（sexual refractory periods）时长，以及挑逗器的复杂程度等相关数据。数据分析环节采用了系统发育广义最小二乘模型（phylogenetic generalised least squares models）。研究未发现挑逗器的存在与否或其复杂程度，与多配水平、雄性性不应期时长，以及雌雄性不应期时长比值之间存在显著关联。然而，雌性性不应期时长与挑逗器的存在呈正相关，与挑逗器的复杂程度呈负相关。因此，本研究数据部分支持"交配后性选择驱动该昆虫类群生殖器演化"这一假说。