STUDIES FOR THE PRESERVATION OF CLOSE-SPECIES RECHNESS

阐明近种共存机制，有助于物种丰富度的保护。行为的多样性，尤其是交配行为的多样性，被认为使近亲之间的生殖隔离，促进了它们的共存。我研究了居住在海岸的半陆生蟹、蟹科和蟹科的交配系统的多样性。招潮蟹（鳉科；招潮蟹属）有80余种，分布在新旧世界的热带和亚热带海岸。一般来说，一些物种生活在同一海岸。雄招潮蟹挥舞着它肥大的大螯，向雌蟹求爱。基于以上的交配行为，我研究了雄蟹对雌蟹身体颜色的偏好。事实证明，雌蟹的身体颜色是由雄蟹选择的。这一结果表明，体色的变化使和保持了近缘种间的生殖隔离，促进了近缘种间的共存。兵蟹（Mictyris brevidactylus）的交配系统与招潮蟹不同。兵蟹在繁殖季节和非繁殖季节改变了它们的活动模式。在繁殖季节，雌性在沙粒形成的沙屋顶下觅食。相反，雄性出现在地面上。在完成表面活动后，雄性螃蟹进入雌性隧道并在洞穴中交配。也就是说，雄性用雌性的隧道作为向导来寻找它们的伴侣。这些研究表明，交配制度的变化与岸边螃蟹的多样性有关。

The clarification of the mechanism for the close-species coexistence is useful for the preservation of species richness. The diversity of the behavior, especially mating behavior is considered to make the reproductive isolation among the close species and to promote the coexistence of them. I studied the diversity of the mating system of semi-terrestrial crabs, Ocypodidae and Mictyridae, which inhabit shores.The fiddler crabs (Ocypodidae ; genus Uca) more than 80 species are distributed the tropical and subtropical shores in the Old and New Worlds. In general, some species inhabit the same shore. The male fiddler crab waves its hypertroph, major cheliped, and courts to the female crabs. I examined the preference for the female's body color by the male crabs, based on the above mating behavior. It was clarified that the female's body color was selected by the male crabs. This result suggests that the variation of body color makes and keeps the reproductive isolation among the close species, and promotes the coexistence of them.The mating system of the soldier crab, Mictyris brevidactylus , differed from that of the fiddler crabs. The soldier crabs changed their activity pattern between reproductive and non reproductive seasons. In the reproductive season, the females fed on beneath the sand roof which was made by sand pellets. In contrast, the males appeared on the ground surface. After engaging in their surface activity, the male crabs entered the females tunnel and mated in the burrows. That is, the males searched their mates using the tunnel of the female as a guide post. These studies showed that the variation of the mating system is related to the diversity of crabs on the shore.