日本地球惑星科学連合2019年大会

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セッション記号 B (地球生命科学) » B-PT 古生物学・古生態学

[B-PT05] 地球生命史

2019年5月30日(木) 13:45 〜 15:15 201A (2F)

コンビーナ:本山 功(山形大学理学部地球環境学科)、生形 貴男(京都大学大学院理学研究科地球惑星科学専攻)、守屋 和佳(早稲田大学 教育・総合科学学術院 地球科学専修)、座長:本山 功生形 貴男守屋 和佳

13:45 〜 14:00

[BPT05-01] 地球生命進化の加速の原因;大量絶滅によって形成される四層構造の地下生物圏が支配するゲノム進化の加速

*丸山 茂徳1金井 昭夫2鳴海 一成3 (1.東京工業大学地球生命研究所、2.慶應大学、3.東洋大学)

キーワード:酸素濃度、地下生物圏、進化の加速

It has long been recognized the concept of five kingdom or six kingdom model which shows the life with difference of function and size. If believing Darwinian Evolution, how can we interpret the diversified distribution with primitive small microbes to the most evolved types of large life. If we consider the most evolved metazoans such as human being to be the result of increased free oxygen in atmosphere, why do the anoxic microbes remain on the surface.
We have engaged in the decoding Earth history Program over 30 years, and obtained the following six results, (1)Since the birth of life until 4.0Ga, three times of Great Evolution of Life (GEL) occurred, (2)Those evolutions were predominantly controlled by the pO2 increase in the environments, (3)Underground bio-communities are present forming 4-layers with boundary layers, (4)Each layer corresponds to different pO2 levels; the older the lower pO2 , (5)In between the two, where two-way genome biomes are present, although speculative, and (6)These four layers could have been formed during the 3 GEL times, accompanying many mass extinctions. Those were remained as fossil environments where evolution stopped, because of no significant environmental changes, in spite of extremely severe surface environments with frequent mass extinction and resultant accelerated evolution of life.
The result corresponds to the concept of 5-6 Kingdom which suggests the preservation of biological communities with different level of pO2 in environments. Through the Earth history, new GEC occurred with great change of pO2 , the advanced life on the surface suffered mass extinctions due to exponentially decreased pO2, instead the underground microbes invaded to the surface, and evolved there again. This is the entity of evolution of life on the earth. Therefore, the presence of robust 4 layered underground biological communities must have contributed to evolving life on this planet, in spite of severe environmental change of planets over 4.0 billion of years in the Universe, not by death, but evolved thorough GEL at 4.0Ga, 2.2Ga and 0.6Ga.