多細胞動物の多段階進化

2013 Fiscal Year Annual Research Report

• Project/Area Number: 23340152
• Research Institution: The University of Tokyo
• Principal Investigator: 小宮 剛 東京大学, 総合文化研究科, 准教授 (30361786)
• Project Period (FY): 2011-04-01 – 2014-03-31
• Keywords: エディアカラ紀 / カンブリア紀 / 後生動物出現 / カンブリア爆発 / 南中国 / 掘削 / 海洋栄養塩濃度 / 多元素多同位体解析

Research Abstract

今年度は初期カンブリア紀寛川溝累層のリン酸塩岩中の微化石やエディアカラ紀中期のリン酸塩岩中の微小化石の三次元像解析を行った。特に、寛川溝累層のリン酸塩岩中の微化石の研究では内部の微細構造が観察され、五放射性構造を得ることができた。その結果は、初期の刺胞動物は五放射性構造をもつ種が多く存在していたとする我々の結果を裏付け、刺胞動物の初期進化をより詳しく解読することに貢献する。また、エディアカラ紀からカンブリア紀の堆積岩の炭素、窒素、Ca同位体変動や炭酸塩のリン濃度変動や火山灰層中のジルコンの年代、卵を保有する節足動物化石や初期刺胞動物の胚化石や幼生化石の３次元像解析、胚化石のFT-IR分析結果やエディアカラ紀～カンブリア紀におけるバイオマーカーの変動と環境環境変動の対比などに関する一連の研究を論文化した。これまでの一連の研究を基に、後生動物の出現と多様化は、酸化還元と栄養塩濃度に関して、対照的な環境条件で起き、前者は比較的還元的な条件で海洋中のリン酸濃度や鉄含有量が高い環境下で、後者は酸化的な条件で、硝酸濃度やCa濃度が高い環境でおきた多段階モデルを提唱した。現在、このモデルの論文化に務めている。また、後生動物の進化は一連の環境変動と極めて良く合うことを示すことから、後生動物の進化・多様化の要素（例えば遺伝子）は、実際に発現するよりも前に保持されており、環境変動に合わせて、それが逐次発現したことを示唆する。

Current Status of Research Progress

Reason

25年度が最終年度であるため、記入しない。

Strategy for Future Research Activity

25年度が最終年度であるため、記入しない。

Research Products

• [Journal Article] Reproductive strategy of the bradoriid arthropod Kunmingella douvillei from the Lower Cambrian Chengjiang Lagerstätte, South China (2014)
  • Author(s): Duan, Y., Han, J., Fu, D., Zhang, X., Yang, X., Komiya, T. & Shu, D.
  • Journal Title: Gondwana Research Volume: 25 Pages: 983-990
  • Peer Reviewed
• [Journal Article] Nitrogen isotope chemostratigraphy of the Ediacaran and Early Cambrian platform sequence at Three Gorges, South China (2014)
  • Author(s): Kikumoto, R., Tahata, M., Nishizawa, M., Sawaki, Y., Maruyama, S., Shu, D., Han, J., Komiya, T., Takai, K. & Ueno, Y.
  • Journal Title: Gondwana Research Volume: 25 Pages: 1057-1069
  • Peer Reviewed
• [Journal Article] New chronological constraints for Cryogenian to Cambrian rocks in the Three Gorges, Weng'an and Chengjiang areas, South China (2014)
  • Author(s): Okada, Y., Sawaki, Y., Komiya, T., Hirata, T., Takahata, N., Sano, Y., Han, J. & Maruyama, S.
  • Journal Title: Gondwana Research Volume: 25 Pages: 1027-1044
  • Peer Reviewed
• [Journal Article] Molecular fossils extracted from the Early Cambrian section in the Three Gorges area, South China (2014)
  • Author(s): Yamada, K., Ueno, Y., Yamada, K., Komiya, T., Han, J., Shu, D., Yoshida, N. & Maruyama, S.
  • Journal Title: Gondwana Research Volume: 25 Pages: 1108-1119
  • Peer Reviewed
• [Journal Article] FTIR microspectroscopy of Ediacaran phosphatized microfossils from the Doushantuo Formation, Weng'an, South China (2014)
  • Author(s): Igisu, M., Komiya, T., Kawashima, M., Nakashima, S., Ueno, Y., Han, J., Shu, D., Li, Y., Guo, J., Maruyama, S., Takai, K.
  • Journal Title: Gondwana Research Volume: 25 Pages: 1120-1138
  • Peer Reviewed
• [Journal Article] The δ13C excursions spanning the Cambrian explosion to the Canglangpuian mass extinction in the Three Gorges area, South China (2014)
  • Author(s): Ishikawa, T., Ueno, Y., Shu, D., Li, Y., Han, J., Guo, J., Yoshida, N., Maruyama, S., Komiya, T.
  • Journal Title: Gondwana Research Volume: 25 Pages: 1045-1056
  • Peer Reviewed
• [Journal Article] The anomalous Ca cycle in the Ediacaran ocean: Evidence from Ca isotopes preserved in carbonates in the Three Gorges area, South China (2014)
  • Author(s): Sawaki, Y., Tahata, M., Ohno, T., Komiya, T., Hirata, T., Maruyama, S., Han, J., Shu, D.
  • Journal Title: Gondwana Research Volume: 25 Pages: 1070-1089
  • Peer Reviewed
• [Journal Article] In-situ analyses of phosphorus contents of carbonate minerals: Reconstruction of phosphorus contents of seawater from the Ediacaran to early Cambrian (2014)
  • Author(s): Shimura, T., Kon, Y., Sawaki, Y., Hirata, T., Han, J., Shu, D., Komiya, T.
  • Journal Title: Gondwana Research Volume: 25 Pages: 1090-1107
  • Peer Reviewed
• [Journal Article] Petrogenesis of the ridge subduction-related granitoids from the Taitao Peninsula, Chile Triple Junction Area (2013)
  • Author(s): Kon, Y., Komiya, T., Anma, R., Hirata, T., Shibuya, T., Yamamoto, S. & Maruyama, S.
  • Journal Title: Geochemical Journal Volume: 47 Pages: 167-183
  • Peer Reviewed
• [Journal Article] Early Cambrian Pentamerous Cubozoan Embryos from South China (2013)
  • Author(s): Han, J., Kubota, S., Li, G., Yao, X., Yang, X., Shu, D., Li, Y., Kinoshita, S., Sasaki, O., Komiya, T., Yang, G.
  • Journal Title: PloS One Volume: 8 Pages: 370741
  • Peer Reviewed
• [Journal Article] The oxygen isotope composition of Earth’s oldest rocks and evidence of a terrestrial magma ocean (2013)
  • Author(s): Rumble, D., Bowring, S., Iizuka, T., Komiya, T., Lepland, A., Rosing, M.T., Ueno, Y.
  • Journal Title: Geochemistry, Geophysics, Geosystems-G3 Volume: 14 Pages: 1929-1939
  • Peer Reviewed
• [Presentation] Heavy Element-Stable Isotope Systematics for Metallomics Induced by the MC-ICPMS Technique (2013)
  • Author(s): Hirata, T., Okabayashi, S., Ohno, T., Yoshiya, K., Komiya, T. & Maruyama, S.
  • Organizer: The 23rd V.M. Goldschmidt Conference
  • Place of Presentation: Firenze Fiera Congress and Exhibition Centre, Florence, Italy
  • Year and Date: 20130830-20130830
• [Presentation] Ion Microprobe U-Pb Dating and Sr Isotope Measurement of a Protoconodont (2013)
  • Author(s): Sano, Y., Toyoshima, K., Shirai, K., Takahata, N., Sato, T. & Komiya, T.
  • Organizer: The 23rd V.M. Goldschmidt Conference
  • Place of Presentation: Firenze Fiera Congress and Exhibition Centre, Florence, Italy
  • Year and Date: 20130829-20130829
• [Presentation] Transition from phosphate to nitrate-rich seawater in the Ediacaran: Implication for diver- sification of mobile metazoans (2013)
  • Author(s): Komiya, T.
  • Organizer: Japan Geoscience Union Meeting 2013
  • Place of Presentation: Makuhari Messe, Makuhari, Japan
  • Year and Date: 20130524-20130524
• [Presentation] Numerical modeling to evaluate carbon cycle changes in the Ediacaran for identifying the cause of the Shuram excursion (2013)
  • Author(s): Tahata, M., Sawaki, Y., Ueno, Y., Komiya, T., Yoshida, N., Nishizawa, M. & Ebisuzaki, T.
  • Organizer: Japan Geoscience Union Meeting 2013
  • Place of Presentation: Makuhari Messe, Makuhari, Japan
  • Year and Date: 20130524-20130524
• [Presentation] Synchrotron X-ray micro-CT analyses of the early Cambrian microfossils: Decoding of the early evolution of Metazoa (2013)
  • Author(s): Komiya, T., Nakao, T., Uesugi, K., Han, J.
  • Organizer: Japan Geoscience Union Meeting 2013
  • Place of Presentation: Makuhari Messe, Makuhari, Japan
  • Year and Date: 20130519-20130519
• [Presentation] Intensive continental weathering rate in the Lower Cambrian: evidenced from Sr isotope ratios preserved in the strata at the Three Gorges area (2013)
  • Author(s): Sawaki, Y., Komiya, T. & Maruyama, S.
  • Organizer: Japan Geoscience Union Meeting 2013
  • Place of Presentation: Makuhari Messe, Makuhari, Japan
  • Year and Date: 20130519-20130519
• [Remarks] 東京大学駒場小宮研究室
  • URL: http://ea.c.u-tokyo.ac.jp/earth/Members/komiya.html