病原体や昆虫の草食動物は,熱帯雨林の植物の多様性と組成を左右しています
Robert Bagchi1, Rachel E Gallery2, Sofia Gripenberg3
11] Department of Zoology, University of Oxford, South Parks Road, Oxford OX1 3PS, UK [2] Ecosystem Management Group, Institute of Terrestrial Ecosystems, ETH Zürich, Universitätstrasse 16, 8092 Zürich, Switzerland.
Nature
|January 28, 2014
まとめ
菌類や昆虫などの特殊な自然敵は,高植物の密度で死亡率を増やすことで熱帯林の生物多様性を維持する. この研究は,ジャンゼン=コネル仮説を裏付け,これらの生物が植物コミュニティの構造化と多様性の保全に不可欠であることを示しています.
科学分野:
- トロピカル生態学 トロピカル生態学
- コミュニティエコロジー
- 生物多様性科学とは生物多様性に関する科学です.
背景:
- 熱帯雨林は膨大な生物多様性を保ちますが,それを維持するメカニズムは完全に理解されていません.
- Janzen-Connell仮説は,特殊な自然敵 (昆虫,病原体) が負密度依存 (NDD) を引き起こし,種の共存を促進すると仮定しています.
- NDDは観察されているが,熱帯植物の多様性を維持するコミュニティ全体の役割は,実験的に検証されていないままである.
研究 の 目的:
- ジャンゼン・コネル仮説を熱帯植物群で実験的に検証する.
- 植物コミュニティの構造化と多様性の維持におけるキノコ病原体と草食昆虫の役割を決定する.
- NDDが種子募集と種組成にどのように影響するかを調査する.
主な方法:
- 熱帯雨林環境における真菌病原体 (殺菌剤を使用) と昆虫の草食動物 (殺菌剤を使用) の実験操作.
- 種から種苗への移行を通じて,植物種の多様性と組成の変化を監視する.
- 種子採用率と同種の種子密度がNDDに与える影響を評価する.
主要な成果:
- 菌類殺菌剤による治療は,種子の多様性を著しく減少させ,ジャンゼン=コネル仮説を裏付けました.
- 昆虫駆除剤の処置は多様性を変化させなかったが,種苗の増殖と種の組成の変化をもたらした.
- NDDは確認され,高密度の同種種の種子,特に豊富な種子の採用が減少しました.
- キノコ抑制は,採用における密度依存の影響を軽減し,NDDによる多様性の維持におけるキノコの役割を強調した.
結論:
- この研究は,熱帯雨林におけるジャンゼン・コネル仮説を支持する強力な実験的証拠を提供します.
- 菌類の病原体は,NDDを通じて熱帯植物の多様性を維持する上で重要な役割を果たします.
- 昆虫や病原菌は,熱帯植物のコミュニティを構成し,その例外的な生物多様性を保存する主要な原動力です.
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