Reproductive Behavior of Polyphemus Limulus

每年春天，大量的马蹄蟹迁徙到大西洋沿岸的海滩上。雌性与雄性附着在一起，埋在沙子里，产卵，雄性在外部受精。独立的雄性聚集在筑巢对周围，有证据表明它们也会使卵受精。拟议的实地研究将描述该物种不同寻常的繁殖行为。通过DNA指纹分析，将确定有配偶和无配偶的后代的比例。描述性观察、标记种群的测量和实验操作将量化筑巢和交配行为以及种群之间的差异。蛙类是独一无二的。剑水龙是现存的唯一一种节肢动物，具有体外受精和水生、自由游泳精子的原始模式。对它们繁殖的研究将为了解现代节肢动物的祖先提供洞察。此外，尽管贻贝是地球上研究最多的物种之一，但人们对它们的繁殖知之甚少。这项实地研究将为它们生物学的其他方面的研究提供有价值的背景，并将利用这些背景。最后，由于它们的同步、半月繁殖和体外受精，贻贝交配与爆炸性繁殖的两栖动物有着深刻的相似之处。因此，对贻贝的研究可能会为交配系统的进化理论提供一个独立的检验。

Every spring large numbers of horseshoe crabs migrate to beaches along the Atlantic coast. Females, with males attached, bury in the sand, laying eggs which the male fertilizes externally. Unattached males aggregate around nesting pairs and evidence suggests that they also fertilize eggs. The proposed field study will characterize the unusual reproductive behavior of this species. The proportion of offspring fathered by attached and unattached males will be determined using DNA fingerprinting. Descriptive observations, measurements of marked populations and experimental manipulations will quantify nesting and mating behavior, and differences between populations. Limulus is unique. The Xiphosurida are the only extant arthropods with the primitive pattern of external fertilization and aquatic, free-swimming sperm. A study of their breeding will provide insight into the ancestors of modern arthropods. Furthermore, although Limulus is one of the best-studied species on the planet, little is known about their reproduction. This field study will provide a valuable context for, and will take advantage of, research on other aspects of their biology. Finally, because of their synchronized, semi-lunar breeding and external fertilization, Limulus mating shows profound similarities to explosively breeding amphibians. Therefore, the study of Limulus may provide an independent test of theories on the evolution of mating systems.