Morphological variability through speciation : A case of a marine planktonic diatom genus Neodenticula

• Project/Area Number: 23540543
• Research Category: Grant-in-Aid for Scientific Research (C)
• Allocation Type: Multi-year Fund
• Section: 一般
• Research Field: Stratigraphy/Paleontology
• Research Institution: Akita University
• Principal Investigator: YAMASAKI Chieko 秋田大学, 工学(系)研究科(研究院), 研究員 (60597186)
• Co-Investigator(Renkei-kenkyūsha): TANIMURA Yoshihiro 国立科学博物館, 地学研究部, 研究G長(退官) (80141985) ; TANAKA Yuichiro 産業技術総合研究所, 地質情報研究部門, 主幹 (50357456) ; SAITO Megumi 国立科学博物館, 地学研究部, 研究員 (40455423) ; YAMASAKI Makoto 秋田大学, 大学院・工学資源学研究科, 准教授 (40344650) ; WATANABE Tsuyoshi 北海道大学, 理学部, 講師 (80396283)
• Project Period (FY): 2011 – 2013
• Project Status: Completed(Fiscal Year 2013)
• Budget Amount: ¥4,290,000 (Direct Cost : ¥3,300,000、Indirect Cost : ¥990,000); Fiscal Year 2013 : ¥260,000 (Direct Cost : ¥200,000、Indirect Cost : ¥60,000); Fiscal Year 2012 : ¥520,000 (Direct Cost : ¥400,000、Indirect Cost : ¥120,000); Fiscal Year 2011 : ¥3,510,000 (Direct Cost : ¥2,700,000、Indirect Cost : ¥810,000)
• Keywords: 珪藻化石 / 形態 / 第四紀 / 北太平洋 / 古気候 / 海底コア / 国際情報交換 / 珪藻 / 種分化 / 古海洋 / 酸素同位体比

Research Abstract

Temporal variability in valvar morphology of a marine planktonic diatom genus Neodenticula was investigated using the Earliest Quaternary sediment cores from the subarctic North Pacific Ocean. Species composition and each species' morphology of the genus changed during the Northern Hemisphere Glaciation, around 2.6 million years ago (Ma).
Drastic morphological change, specifically, a dominance of a "peculiar" type, was recorded just before the extant species appeared in 2.55 Ma based on a biometric measurement of valves. On the other hand, the culture experimental results of the species indicated that the peculiar type appeared when the higher growth rates and lower availability of the major nutrients were brought(Shimada et al., 2009). Thus, we suggest that the moprhological event of the diatom genus in the subarctic Northwestern Pacific Ocean around 2.6 Ma may have reflect a short-term collapse of the nutrient regime in the ocean.

Research Products

• [Journal Article] Murakami, M., Shimada, C., Hikida,Y. and Hirano, H. (2012)
  • Author(s): A new basal porpoise, Pterophocaena nishinoi (Cetacea, Odontoceti, Delphinoidea), from the upper Miocene of Japan and its phylogenetic relationships.
  • Journal Title: Journal of Vertebrate Paleontology Volume : 32
  • Peer Reviewed
• [Presentation] 外洋性浮遊珪藻Neodenticula の形態多様性とNorthern Hemisphere Glaciation (2013)
  • Author(s): 嶋田 智恵子・田中裕一郎
  • Organizer: 日本古生物学会年会
  • Place of Presentation: 熊本大学
• [Presentation] 外洋性浮遊珪藻Neodenticulaの形態多様性とNorthern Hemisphere Glaciation (2013)
  • Author(s): 嶋田智恵子・田中裕一郎
  • Organizer: 日本古生物学会
  • Place of Presentation: 熊本大学