STUDIES FOR THE PRESERVATION OF CLOSE-SPECIES RECHNESS

阐明近缘种共存的机制对保护物种丰富度具有重要意义。行为的多样性，尤其是交配行为的多样性，被认为是造成近缘种间生殖隔离，促进近缘种间共存的重要原因。研究了半陆栖的招潮蟹（Ocypodidae）和招潮蟹（Mictyridae）的交配系统多样性，招潮蟹（Ocypodidae ; Uca属）有80多种，分布于新旧大陆的热带和亚热带海岸。一般来说，有些物种栖息在同一个海岸。雄性招潮蟹向雌性招潮蟹挥动它的肥大的大螯肢和求爱。基于上述交配行为，我研究了雄蟹对雌蟹体色的偏好。结果表明，雌蟹的体色是由雄蟹选择的。这一结果表明，体色的变化使近缘种间的生殖隔离得以维持，促进了近缘种间的共存。短趾叉尾蟹的交配系统不同于招潮蟹。兵蟹在繁殖季节和非繁殖季节的活动模式发生了变化。在繁殖季节，雌虫在由沙粒制成的沙屋顶下觅食。相反，男性出现在地面上。雄蟹在水面活动后，进入雌蟹的洞穴，在洞穴中交配。也就是说，雄性利用雌性的隧道作为路标来搜索它们的配偶。这些研究表明，交配系统的变化与海岸蟹类的多样性有关。

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.