Universality and hierarchy in evolutionary pattern-approach from "marine insect" Ostracoda

通过这项工作了解介形类陶器的进化特征。海生介形类可能是介形类中最多样化的类群，在古近纪以其多样性的增加而闻名。证明了该超家族具有与其他原始超家族，如贝类总科和猫眼总科的同态特征。这从甲壳中的毛孔数量和臂板中的刚毛数量中可以看出。这些结果是通过个体发育对每个超家族的代表进行详细观察和描述而得到的。在物种形成和进化的过程和时间上，重点研究了猫科和担纲总科的4个属。在日本、菲律宾和北美西海岸对它们的分类和地理分布进行了研究。在这些属的进化过程中发现的共同模式导致了这样的结论：与世界其他地区相比，日本周围相关物种的生物多样性非常高。这些近缘物种分别生活在太平洋、日本海、鄂霍次克海和寒冷的Oyashio地区，与洋流和/或海洋气候区划相对应。这可能是因为第四纪冰期海平面的变化导致了边缘海的孤立，最终导致了能够适应冰期寒冷气候的突变的自然选择。如上所述，通过本研究，首次获得了适用于孤立边缘海域的演化模式。

Evolutionary characteristics of ostracodes ware comprehended through this work. Marine cytheroidean ostrcaodes, which are probably most diversified taxa in ostracodes, are known for its increasing of diversity in Paleogene. The super family is proved to have paedomorphic characters against the other primitive superfamilies such as Bairdoidea and Cythpridoidea. This is seen in the number of pores in carapaces and the number of setae in brachial plates. The results are obtained from the detail observation and description of representatives from each superfamilies through ontogeny. On the other hand, four genera belonging to the superfamily cytheroidea and bairdioidea were especially studied well on the process and timing of the speciation and evolution. They were the genera Loxoconcha, Xestoleberis, Paradoxostoma of cytheroidea and the genus Neonesidea of bairdoidea, and their taxonomiy and geographical distribution were studied in Japan, Philippines and the west coast of North America. The common pattern found in the evolution of these genera lead to the conclusion that the biodiversity of related species are extgremely high around Japan compared with other areas in the world. These related species are living separately in Pacific, Sea of Japan, Okhotsk Sea and cold Oyashio areas, which corresponds to the currents and/or marine climatic divisions. The reason of this fact may be because the glacial eustatic sea level changes in the Quaternary caused the isolation of the marginal seas, and eventually a natural selection for the mutation which was able to adapt to the cold climate during glacial ages. As mentioned above, through this study, the evolutionary model which can be applicable to the isolated marginal sea area was first acquired.