捕食のリスクは,エルクの生殖生理学と人口統計に影響します
Scott Creel1, David Christianson, Stewart Liley
1Department of Ecology, Montana State University, 310 Lewis Hall, Bozeman, MT 59717, USA. screel@montana.edu
まとめ
イエローストーンにオオカミ (Canis lupus) が存在すると,エルク (Cervus elaphus) の行動が変化し,繁殖の成功が低下する. エルクにおける捕食者に対する警戒性の向上は,プロゲステロンのレベルが低下し,子牛の募集と相関しています.
科学分野:
- エコロジー エコロジー エコロジー
- 野生生物生物学 野生生物生物学
- 生殖生理学 生殖生理学
背景:
- 捕食者-獲物のダイナミクスは,野生動物の行動と人口の健康に大きな影響を与えます.
- グレーター・イエローストーン生態系は,エルクとオオカミの複雑な相互作用をサポートしています.
- 反捕食者の行動は,獲物の種にとって生理学的コストを伴う可能性があります.
研究 の 目的:
- オオカミの存在がエルク集団に及ぼす生理学的および人口学的影響を調査する.
- 鹿の反捕食者行動が生殖生理学に影響するかどうかを判断する.
- オオカミとエルクの比率,エルクのストレスホルモン,そして子牛の徴募の関係を評価する.
主な方法:
- 16のサイト年以上の5つのエルク集団からの1489の糞便サンプルを分析した.
- 生理学的ストレスの指標としての排泄中のプロゲステロン濃度の測定.
- プロゲステロン濃度の相関関係とエルク対オオカミの比率,およびその後の子牛の徴募率.
主要な成果:
- エルクの便中のプロゲステロン濃度は,エルクとオオカミの比率が低下するにつれて著しく減少しました.
- 低プロゲステロンレベルは,翌年の小牛の募集の減少を強く予測しました.
- これらの発見は,エルクの反捕食者行動に関連する生理学的コストを示しています.
結論:
- オオカミの存在は,鹿の生殖生理学と人口統計に間接的に影響を与えます.
- オオカミの存在によって媒介される反捕食者の行動のコストは,エルク集団のダイナミクスに影響を与えます.
- これらの間接的な影響を理解することは,捕食動物に富んだ生態系における野生生物の管理に極めて重要です.
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