クモの個体数:トップの捕食者がいない島々で非常に高い密度

T W Schoener, C A Toft

Science (New York, N.Y.)

|March 18, 1983

まとめ

島々でのオーブクモの個体数は大きく異なっています. 密度は大陸からの距離とともに減少し,脊椎動物の捕食者が欠けている島では10倍高い.

科学分野:

島のバイオジオグラフィー
アラクロノジーアラクロノジー
エコロジーエコロジーエコロジー

背景:

小島でのオーブクモの分布と密度は,著しい変動を示しています.
種の発生は,同じ島の脊椎動物と比較して,クモにとって予測が難しい.

研究の目的:

球状クモの密度と小島での分布に影響を与える要因を調査する.
コロニゼーション源と脊椎動物捕食者からの距離がクモの集団に与える影響を決定する.

主な方法:

さまざまな小さな島々でのオーブクモの分布と密度データの分析.
距離と捕食者の存在がクモの集団に与える影響を評価するための統計モデリング.

主要な成果:

クモの密度は,推定された植民地化源からの距離が増加するにつれて指数関数的に減少し,受動的な分散予測と一致します.
脊椎動物の捕食動物を持たない島は,類似の距離にあるそのような捕食動物を持つ島よりも約10倍大きい球状のクモの密度をサポートします.

結論:

ソース集団からの距離と脊椎動物捕食者の存在は,球状蜘蛛島コミュニティ構造の主要な要因です.
捕食者の不在は,球状クモのコロニー化成功と島の人口密度を大幅に高めます.

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