氷河期の海藻の増殖と動物の出現
Jochen J Brocks1, Amber J M Jarrett1, Eva Sirantoine1
1Research School of Earth Sciences, The Australian National University, Canberra, Australian Capital Territory 2601, Australia.
Nature
|August 17, 2017
まとめ
海の生態系は6億5900万年前には 細菌から藻類の支配に移り
科学分野:
- 古代海洋学
- 海洋生態学
- 分子古生物学
背景:
- 細菌から真核生物の原始生産性への移行は,海洋生態系を大きく変えて,炭素と栄養素の循環とより高いトロフィックレベルへのエネルギー転送に影響を与えました.
- 原因,タイミング,大気中の酸素と動物の進化との関連は不明である.
研究 の 目的:
- 海洋における ユカリオット原生体の発生の時期と原因を再構築する.
- この移行が海洋の食物網と動物の進化に及ぼす生態学的影響を調査する.
主な方法:
- 過去の主要生産者を特定するために,分子化石記録,特に真核ステロイドの分析.
- 地質学的な出来事の年代付けは,スチュルティアとマリノアの"スノーボール地球"の氷河期を含んで,タイムラインを確立します.
主要な成果:
- 低温期 (7億2000万年前) 前に細菌が唯一の主要な生産者であった.
- 海洋プランクトン藻類 (Archaeplastida) は,ストルティア氷河期の後,6億5500万年前から急速に出現した.
- スポンジとリザリアンのバイオマーカーは同時に現れ,エディアカラン期にはユーメタゾアンの放射線が続いた.
結論:
- ストゥルティアの脱氷期は 栄養素の急増をもたらし 藻類がサイアノバクテリアと 競争することを可能にした
- 藻類の増殖により 栄養素とエネルギーの伝達が促進され より複雑な食物網と より大きな生物が支えられました
- この生態学的革命は,その後の初期の動物の進化と多様化に関連しています.
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