The causal relationship between sexual selection and sexual size dimorphism in marine gastropods

Sexual size dimorphism is widespread among dioecious species but its underlying driving forces are often complex. A review of sexual size dimorphism in marine gastropods revealed two common patterns: firstly, sexual size dimorphism, with females being larger than males, and secondly females being larger than males in mating pairs; both of which suggest sexual selection as being causally related with sexual size dimorphism. To test this hypothesis, we initially investigated mechanisms driving sexual selection on size in three congeneric marine gastropods with different degrees of sexual size dimorphism, and, secondly, the correlation between male/female sexual selection and sexual size dimorphism across several marine gastropod species. Male mate choice via mucus trail following (as evidence of sexual selection) was found during the mating process in all three congeneric species, despite the fact that not all species showed sexual size dimorphism. There was also a significant and strong ...性别大小二态性（Sexual size dimorphism）在雌雄异体物种中广泛存在，但其内在驱动机制往往错综复杂。针对海洋腹足类动物（marine gastropods）的性别大小二态性综述研究揭示了两类常见模式：其一为雌性体型大于雄性的性别大小二态性，其二为交配对中雌性个体体型大于雄性；二者均表明性选择（sexual selection）与性别大小二态性存在因果关联。为验证该假说，我们首先对3个具有不同程度性别大小二态性的同属海洋腹足类物种，开展了体型相关性选择驱动机制的研究；其次则探究了多种海洋腹足类物种中雌雄两性性选择与性别大小二态性之间的相关性。在3个同属物种的交配过程中，尽管并非所有物种均表现出性别大小二态性，但均观察到雄性通过跟随黏液痕迹（mucus trail following）进行配偶选择的行为（该行为可作为性选择的佐证）。此外，二者间还存在显著且强烈的……