Data from: Phylogeny suggests non-directional and isometric evolution of sexual size dimorphism in argiopine spiders

Sexual dimorphism describes substantial differences between male and female phenotypes. In spiders, sexual dimorphism research almost exclusively focuses on size, and recent studies have recovered steady evolutionary size increases in females, and independent evolutionary size changes in males. Their discordance is due to negative allometric size patterns caused by different selection pressures on male and female size (converse Rensch’s rule). Here, we investigated macroevolutionary patterns of sexual size dimorphism (SSD) in Argiopinae, a global lineage of orb weaving spiders with varying degrees of SSD. We devised a Bayesian and maximum likelihood molecular species level phylogeny, then used it to reconstruct sex specific size evolution, to examine general hypotheses and different models of size evolution, to test for sexual size coevolution, and to examine allometric patterns of SSD. Our results, revealing ancestral moderate sizes and SSD, failed to reject the Brownian motion model, which suggests a non-directional size evolution. Contrary to predictions, male and female sizes were phylogenetically correlated, and SSD evolution was isometric. We interpret these results to question the classical explanations of female-biased SSD via fecundity, gravity, and differential mortality. In argiopines, SSD evolution may be driven by these or additional selection mechanisms, but perhaps at different phylogenetic scales.性二态性（Sexual dimorphism）指雌雄个体表型间存在的显著差异。在蜘蛛类群中，性二态性的研究几乎仅聚焦于体型维度，现有研究已证实雌性体型呈现稳定的进化增长趋势，而雄性体型的进化则呈现独立的变化模式。二者的进化模式不一致，源于雌雄体型受到不同选择压力所催生的负异速生长体型格局，即反伦斯法则（converse Rensch’s rule）。本研究聚焦于金蛛亚科（Argiopinae）——一类分布于全球、性体型二态性（Sexual Size Dimorphism，SSD）程度存在差异的结圆网蜘蛛类群——的性体型二态性宏观进化格局。我们构建了基于分子数据的贝叶斯（Bayesian）与最大似然法（maximum likelihood）物种水平系统发育树，以此重构雌雄各自的体型进化历程，检验体型进化的通用假说与各类进化模型，验证性体型协同进化假说，并剖析SSD的异速生长格局。研究结果显示，该类群的祖先体型与SSD均处于中等水平，且未拒绝布朗运动模型（Brownian motion model），这表明体型进化呈现无方向性特征。与此前的预测相悖的是，雌雄体型在系统发育上呈现显著相关性，且SSD的进化符合等速生长模式。基于上述结果，我们对雌性偏向型SSD的经典解释——即基于繁殖力、重力与差异化死亡率的解释——提出了质疑。在金蛛亚科类群中，SSD的进化或许受上述或其他选择机制驱动，但可能在不同的系统发育尺度下发挥作用。