Paleobiological research on the history of earth organisms modeled by the submarine cave ecosystem

1. 系统地描述了甲壳类2新种，软壳类腹足类1新属3新种。海底洞穴的一个独特的生态特征是捕食动物很少，让人想起中生代中期的浅海生态系统。为了比较现代海底洞穴与中中生代浅海生态系统的生态特征，我们研究了贝壳钻壳、捕食性蓝藻腹足类的历史，因为它们代表了捕食者-猎物关系的最佳化石记录。我们发现，蓝藻最早出现在白垩纪末期，从那时起就开始钻探捕食。另一方面，我们在日本南部冲绳的两个海底洞穴中检测了低至5%的钻孔和破碎捕食，其频率与晚白垩世浅海组合相当。这是关于海底洞穴中捕食活动的第一份文件。在菲律宾两个相距200多公里的岛屿的岩洞中发现了海绵状黑檀。我们提出了安切林洞穴生物的第一个遗传结构（线粒体细胞色素氧化酶I），这表明岛屿之间没有遗传隔离的证据。所有个体都是泛疫种群的一部分，它们看似孤立的洞穴栖息地并没有限制这个物种的基因流动。幼虫分散可能广泛适用于岛状分布的刺甲粘虫。对沙蚕科的分类学研究表明，沙蚕科的物种多样性在东南亚岛屿最高，并随着距离多样性中心的距离而逐渐减小。与先前被广泛接受的观点相反，海绵状动物主要是通过板块构造和间隙分散的，而越洋扩散应该像热带珊瑚礁海中的大多数现代无脊椎动物一样，在形成海绵状海绵动物目前的分布中发挥了重要作用。

1. We systematically described two new species of mysid crustaceans and one new genus and three new species of neritilid gastropods.2. A unique ecological feature in submarine caves is the infrequency of predator animals, reminiscent of the mid-Mesozoic shallow marine ecosystem. To compare the ecological features between the modern submarine caves and mid-Mesozoic shallow marine ecosystem, we studied the history of shell-drilling, predatory naticid gastropods as they represent the best fossil records of predator-prey relationship. We showed that naticids first appeared in the end of Cretaceous and started drilling predation since that time. On the other hand, we examined drilling and crushing predation in shells of two submarine caves of Okinawa, southern Japan as low as 5%, the frequency is equivalent to those for the late Cretaceous shallow marine assemblages. This is the first documentation of predatory activity in submarine caves.3. Neritilia cavernicala n. sp. was described from anchialine caves of two islands separated more than 200km apart in the Philippines. We presented the first genetic structure for anchailine cave organisms (mitochondrial cytochrome oxidase I), which shows no evidence of genetic isolation between the islands. All individuals are part of a panmictic population and their seemingly isolated cave habitats do not limit gene flow in this species. Larval dispersal may be widely applicable to anchialine stygobites with insular distributions.4. A taxonomic study of Nerilitidae shows the species diversity is the highest in SE Asian islands and becomes smaller in accordance with the distance from the diversity center. Contrast to the previous, widely accepted view that cavericolous animals dispersed primarily by plate tectonics and vicariance, transoceanic dispersal should have played an important role, like most modern invertebrates in tropical coral-reef seas, in forming the present distribution of the cavericolous neritilids.