カンブリア紀はトリロバイト種の形態学的多様性のピーク期であった
1Department of the Geophysical Sciences, University of Chicago, 5734 South Ellis Avenue, Chicago, IL 60637, USA. mwebster@geosci.uchicago.edu
Science (New York, N.Y.)
|July 28, 2007
まとめ
トリロバイトの種は,進化の初期に最も多くの形態学的変化を示した. この高い種内多様性はカンブリア爆発を助長し,三角生物の多様化を促したのかもしれない.
科学分野:
- パレオントロジー・パレオントロジー
- 進化生物学の進化生物学について
- 地質学 地質学 地質学
背景:
- 種内の形態学的多様性は,自然選択において極めて重要です.
- 以前の研究では,物種内ではなく,物種間での変化に時間をかけて焦点を当てていた.
- 形態学的多様性における時間的な変化を理解することは,進化の洞察の鍵である.
研究 の 目的:
- トリロバイト種内の形態学的変化の時間的動態を調査する.
- 進化の過程で形態学的多様性が変化するかどうかを判断する.
- カンブリア時代のトリロバイトの多様化における種内多様性の役割を評価する.
主な方法:
- クラディスティックな特徴-分類マトリックスにおけるポリモルフィック特性の分析.
- 982種のトライロバイトの形態学的多様性の検討.
- 化石分類のストラティグラフィックと系統遺伝分析.
主要な成果:
- 形態学的多様性は,初期に進化し,系統遺伝学的に基礎的なトリロバイト種に最大であった.
- Stratigraphically older trilobitesは,より若い,派生した分類よりも著しく高い変動性を示しました.
- 高い種内変動と初期の進化的放射の間で強い相関関係がある.
結論:
- トリロバイトの種内形態学的変異は,その進化の歴史の初期にピークに達した.
- 高い種内多様性は,カンブリア期におけるトリロバイトの急速な多様化を促進した可能性がある.
- この発見は,マクロ進化パターンを駆動する種内変動の重要性を強調しています.
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