Fernández-Montraveta Carmen, Marugán-Lobón Jesús
Departamento de Psicología Biológica y de la Salud, Universidad Autónoma de Madrid, Madrid, Spain.
Departamento de Biología, Universidad Autónoma de Madrid, Madrid, Spain.
PeerJ. 2017 Jul 26;5:e3617. doi: 10.7717/peerj.3617. eCollection 2017.
Common scientific wisdom assumes that spider sexual dimorphism (SD) mostly results from sexual selection operating on males. However, testing predictions from this hypothesis, particularly male size hyperallometry, has been restricted by methodological constraints. Here, using geometric morphometrics (GMM) we studied for the first time sex-differential shape allometry in a spider (, Araneae: Lycosidae) known to exhibit the reverse pattern (i.e., male-biased) of spider sexual size dimorphism. GMM reveals previously undetected sex-differential shape allometry and sex-related shape differences that are size independent (i.e., associated to the y-intercept, and not to size scaling). Sexual shape dimorphism affects both the relative carapace-to-opisthosoma size and the carapace geometry, arguably resulting from sex differences in both reproductive roles (female egg load and male competition) and life styles (wandering males and burrowing females). Our results demonstrate that body portions may vary modularly in response to different selection pressures, giving rise to sex differences in shape, which reconciles previously considered mutually exclusive interpretations about the origins of spider SD.
常见的科学观点认为，蜘蛛的两性异形（SD）主要是由作用于雄性的性选择导致的。然而，对这一假设的预测进行检验，尤其是对雄性体型超异速生长的检验，一直受到方法上的限制。在此，我们首次使用几何形态测量学（GMM），对一种已知呈现蜘蛛性大小异形的反向模式（即雄性偏向）的蜘蛛（蜘蛛目：狼蛛科）的性别差异形状异速生长进行了研究。GMM揭示了先前未被检测到的性别差异形状异速生长以及与性别相关的、与大小无关的形状差异（即与y轴截距相关，而非与大小缩放相关）。性形状异形既影响头胸甲与腹部的相对大小，也影响头胸甲的几何形状，这可以说是由生殖角色（雌性的卵负荷和雄性的竞争）和生活方式（游荡的雄性和穴居的雌性）的性别差异导致的。我们的研究结果表明，身体各部分可能会根据不同的选择压力进行模块化变化，从而产生形状上的性别差异，这调和了先前关于蜘蛛两性异形起源的相互排斥的解释。
