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ゼナコエロモルファはネフロゾアの姉妹群である
Johanna Taylor Cannon1, Bruno Cossermelli Vellutini2, Julian Smith3
1Naturhistoriska Riksmuseet, PO Box 50007, SE-104 05 Stockholm, Sweden.
Nature
|February 5, 2016
まとめ
主要な双極性特性を欠く海洋虫であるクセナコエロモルファの系統的位置が明確にされる. 我々の研究により,クセナコエロモルファは 他のビラテリア (ネフロゾア) の姉妹群であると明らかにされ, 初期の動物の進化に関する我々の理解を形づくっています
科学分野:
- 動物学
- 進化生物学
- 系統遺伝学
背景:
- クセナコエロモルファ (Acoela,Nemertodermatida,Xenoturbella) の動物系統における位置づけは議論されている.
- ゼナコエロモルファには,門やネフリディアのような共通の双胞胎の特徴がないため,すべての双胞胎の姉妹またはデウテロストミアという2つの仮説が提唱されている.
- この問題を解くことは 初期双極進化や二次的な複雑性喪失を理解するために 極めて重要です
研究 の 目的:
- 動物界におけるクセナコエロモルファの 精密な遺伝的位置を決定する
- クセナコエロモルファの進化的関係に関する矛盾する仮説を解決する確固たる証拠を提供すること.
- 遺伝学的な位置づけに基づいて 双方の祖先の特徴を再構築する
主な方法:
- 11つの新しいクセナコエロモルフのトランスクリプトームを用いた系統分析.
- 最大確率とベイジアン推論の方法を様々な進化モデルで適用する.
- 25のデータセットを 厳格にテストし 長枝引力や飽和度 欠落したデータなどの 潜在的なバイアスを軽減します
主要な成果:
- Xenacoelomorphaは,ネフロゾア (残りのすべてのバイラテリア) の姉妹分類体として,堅固な遺伝学的な支持が得られた.
- 分析により,異なるモデルにおけるこの関係が確認され,潜在的な再構築バイアスに耐えた.
- 姉妹グループ関係は一貫して回復し,代替仮説を否定した.
結論:
- ゼナコエロモルファはネフロゾアの姉妹群を表し 生命の樹上の位置を明確にしています
- この発見は,最後の共通の双方の祖先が シンプルで毛皮状のアケロマトワームだったことを示しています
- 排泄器官や神経などの重要な双方の特徴は,ネフロゾア系からクセナコエロモルファの分岐後に進化した.
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