Institute of Biology, Research Centre of the Slovenian Academy of Sciences and Arts, Ljubljana, Slovenia.
Department of Organisms and Ecosystems Research, Evolutionary Zoology Laboratory, National Institute of Biology, Ljubljana, Slovenia.
Naturwissenschaften. 2021 Oct 14;108(6):54. doi: 10.1007/s00114-021-01754-w.
Adult body size, development time, and growth rates are components of organismal life histories, which crucially influence fitness and are subject to trade-offs. If selection is sex-specific, male and female developments can eventually lead to different optimal sizes. This can be achieved through developmental plasticity and sex-specific developmental trajectories. Spiders present suitable animals to study differences in developmental plasticity and life history trade-offs between the sexes, because of their pronounced sexual dimorphism. Here, we examine variation in life histories in the extremely sexually size dimorphic African hermit spider (Nephilingis cruentata) reared under standardized laboratory conditions. Females average 70 times greater body mass (and greater body size) at maturity than males, which they achieve by developing longer and growing faster. We find a small to moderate amount of variability in life history traits to be caused by family effects, comprising genetic, maternal, and early common environmental effects, suggesting considerable plasticity in life histories. Remarkably, family effects explain a higher variance in male compared to female life histories, implying that female developmental trajectories may be more responsive to environment. We also find sex differences in life history trade-offs and show that males with longer development times grow larger but exhibit shorter adult longevity. Female developmental time also correlates positively with adult body mass, but the trade-offs between female adult mass, reproduction, and longevity are less clear. We discuss the implications of these findings in the light of evolutionary trade-offs between life history traits.
成年体型、发育时间和生长速度是生物生活史的组成部分，它们对适应度有至关重要的影响，并受到权衡取舍的影响。如果选择是性别特异性的，那么男性和女性的发育最终可能导致不同的最佳体型。这可以通过发育可塑性和性别特异性发育轨迹来实现。蜘蛛是研究性别间发育可塑性和生活史权衡差异的理想动物，因为它们具有明显的性二型性。在这里，我们研究了在极度性体型二态性的非洲隐士蜘蛛（Nephilingis cruentata）在标准化实验室条件下饲养时生活史的变化。与雄性相比，雌性在成熟时的平均体质量（和体型）大 70 倍，这是通过发育更长和生长更快实现的。我们发现，由家族效应引起的生活史特征的小到中等程度的可变性，包括遗传、母体和早期共同环境效应，这表明生活史具有相当大的可塑性。值得注意的是，与雌性相比，家族效应在雄性生活史中解释了更高的方差，这意味着雌性的发育轨迹可能对环境更敏感。我们还发现了生活史权衡中的性别差异，并表明发育时间较长的雄性生长得更大，但成年寿命较短。女性的发育时间也与成年体质量呈正相关，但女性成年体质量、繁殖和寿命之间的权衡关系不太清楚。我们根据生活史特征之间的进化权衡来讨论这些发现的意义。
