Formation of present marine and terrestrial faunas through environmental changes in the Pan-Japan Sea area
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It is said to be about 16 million years ago that the Japanese islands started to separate from the Asian Continent and the Proto-Japan Sea was born. Since then the Sea and the surrounding areas suffered various environmental changes. For example, warm/tropical periods appeared at 15 million, 14 million and 11 million years ago during otherwise the generally temperate climates, and the warm water (Kuroshio) periodically entered into the Japan Sea. Between 2 million years ago and the present, cyclic climate changes (glacial/interglacial) with short periodicity of tens of thousand years have been dominant. A lot of marine organisms are known to have extinguished while they have also evolved and diversified through the periods.
Ostracoda, a small Crustacea, has been the main material in my laboratory to pursue the subject " when, where and how the evolution of marine organism happened". As the results, the process of the formation of the present fauna has been shown through the couple of "evolutionary events". The evolutionary pattern found last 2 million years is particularly specific to the marginal sea area such as Japan Sea and Okhotsk Sea, and was modeled as a "marginal sea pumping effect".
The purpose of the present study is to continue to work on the role of Japan Sea in the extinction and evolution of marine organisms. The additional study of terrestrial (freshwater) Ostracoda on their distribution, extinction and evolution will help to understand the essence of these phenomena. Without doubt, these basic data will also make Ostracoda a great sensor for the estimate of environments of the past, the present and the future.
