肉食動物は,獲物集団の壊滅的な絶滅のリスクを高めます
T W Schoener1, D A Spiller, J B Losos
1Section of Evolution and Ecology, University of California, Davis, California 95616, USA. twschoener@ucdavis.edu
Nature
|July 13, 2001
まとめ
ハリケーンなどの壊滅的な干渉と相互作用する捕食者は,獲物の集団を絶滅に追い込むことができます. この研究では,導入された捕食動物が,大規模なハリケーン発生時に島の絶滅リスクを拡大したことを示しています.
科学分野:
- エコロジー エコロジー エコロジー
- 保護生物学の保護生物学
- 島のバイオジオグラフィー
背景:
- エコロジカル・リサーチでは,上から下への影響 (捕食) と干渉を別々に検討することが多い.
- 捕食と壊滅的な混乱が生態系コミュニティに与える影響,特に絶滅につながる影響は十分に研究されていない.
研究 の 目的:
- 獲物の絶滅の確率に対する捕食と壊滅的な干渉の相互作用効果を調査する.
- 大規模なハリケーンの後,捕食者の存在が獲物集団の回復力をどのように影響するか評価する.
主な方法:
- バハマ諸島に捕食動物を実験的に導入した.
- 大規模なハリケーンが起こる前と後のトカゲの個体数の大きさを監視する.
- 導入された捕食動物がいる島と存在しない島間の集団回復率を比較する.
主要な成果:
- 導入された捕食動物を持つ島々は,ハリケーンの後,サカの集団の絶滅を経験したが,コントロール島はそうしなかった.
- 肉食動物はハリケーン前半の獲物数を減らし,ハッカリングの生存率はハリケーン後,肉食動物島で低かった.
- 獲物の回復はコントロール島で成功したが,捕食者の導入島の3分の2では失敗し,地元の絶滅につながった.
結論:
- 捕食と災害的な気候の乱れがもたらす相乗効果は,獲物集団の絶滅につながる可能性があります.
- 捕食は,獲物の回復力を低下させ,極端な環境現象の際に絶滅の危機に瀕する集団をより脆弱にすることができます.
- 保護戦略は,脆弱な集団に対する複数のストレス要因の組み合わせた影響を考慮する必要があります.
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