Incorporating an ontogenetic perspective into evolutionary theory of sexual size dimorphism

Sexual size dimorphism (SSD) describes divergent body sizes of adult males and females. While SSD has traditionally been explained by sexual and fecundity selection, recent advances in physiology and developmental biology emphasize that SSD would occur proximately because of sexual differences in ontogenetic growth trajectories (i.e., growth rate and duration). Notably, these ontogenetic traits are subject to energetic or time constraints and thus traded off with fitness components (e.g., survival and reproduction). To elucidate the importance of such ontogenetic trade-offs in the evolution of SSD, we developed a new theoretical framework by extending quantitative genetic models for the evolution of sexual dimorphism in which we reinterpret the trait as body size and reformulate sex-specific fitness in size-dependent manners. More specifically, we assume that higher growth rate or longer growth duration leads to larger body size and higher reproductive success but incurs the cost of low...

性大小二态性（Sexual size dimorphism, SSD）指成年雄性与雌性个体间的体型分化。传统上，该现象常以性选择与繁殖力选择进行解释，但近年来生理学与发育生物学的研究进展强调，性大小二态性的直接成因是雌雄个体在个体发育生长轨迹（即生长速率与生长时长）上的差异。值得注意的是，此类个体发育性状会受到能量或时间限制，因此与适合度组分（如存活与繁殖）存在权衡关系。为阐明此类个体发育权衡在性大小二态性演化中的重要性，本研究拓展了用于性二态性演化的定量遗传模型，构建了全新的理论框架：将该性状重新定义为体型，并以体型依赖的方式重新构建了性别特异性适合度。具体而言，本研究假设更高的生长速率或更长的生长时长可使个体体型更大、繁殖成功率更高，但会付出低……的代价。