Blanckenhorn Wolf U, Dixon Anthony F G, Fairbairn Daphne J, Foellmer Matthias W, Gibert Patricia, van der Linde Kim, Meier Rudolf, Nylin Sören, Pitnick Scott, Schoff Christopher, Signorelli Martino, Teder Tiit, Wiklund Christer
Zoologisches Museum, Universität Zürich-Irchel, Winterthurerstrasse 190, CH-8057 Zürich, Switzerland.
Am Nat. 2007 Feb;169(2):245-57. doi: 10.1086/510597. Epub 2006 Dec 20.
A prominent interspecific pattern of sexual size dimorphism (SSD) is Rensch's rule, according to which male body size is more variable or evolutionarily divergent than female body size. Assuming equal growth rates of males and females, SSD would be entirely mediated, and Rensch's rule proximately caused, by sexual differences in development times, or sexual bimaturism (SBM), with the larger sex developing for a proportionately longer time. Only a subset of the seven arthropod groups investigated in this study exhibits Rensch's rule. Furthermore, we found only a weak positive relationship between SSD and SBM overall, suggesting that growth rate differences between the sexes are more important than development time differences in proximately mediating SSD in a wide but by no means comprehensive range of arthropod taxa. Except when protandry is of selective advantage (as in many butterflies, Hymenoptera, and spiders), male development time was equal to (in water striders and beetles) or even longer than (in drosophilid and sepsid flies) that of females. Because all taxa show female-biased SSD, this implies faster growth of females in general, a pattern markedly different from that of primates and birds (analyzed here for comparison). We discuss three potential explanations for this pattern based on life-history trade-offs and sexual selection.
性大小二态性（SSD）的一个显著种间模式是伦施法则，根据该法则，雄性体型比雌性体型更具变异性或在进化上更具分化性。假设雄性和雌性的生长速率相等，那么SSD将完全由发育时间的性别差异，即性双熟现象（SBM）介导，而伦施法则则直接由其导致，体型较大的性别发育时间相对更长。在本研究调查的七个节肢动物类群中，只有一部分表现出伦施法则。此外，我们总体上仅发现SSD与SBM之间存在微弱的正相关关系，这表明在广泛但绝不是所有节肢动物类群中，性别间生长速率差异在直接介导SSD方面比发育时间差异更为重要。除了雄性先熟具有选择优势的情况（如在许多蝴蝶、膜翅目昆虫和蜘蛛中），雄性发育时间与雌性相等（如水黾和甲虫），甚至比雌性更长（如果蝇和蚤蝇）。由于所有类群都表现出雌性偏向的SSD，这意味着一般来说雌性生长更快，这一模式与灵长类动物和鸟类（在此作为比较进行分析）明显不同。我们基于生活史权衡和性选择讨论了这种模式的三种潜在解释。
