インブリーディングのレベルの変化が遺伝的負荷に及ぼす影響

S C Barrett¹, D Charlesworth

¹Department of Botany, University of Toronto, Ontario, Canada.

Nature

|August 8, 1991

まとめ

インブリーディングは有害な突然変異アレルを除去し,時間とともに遺伝的負荷を軽減します. この研究は,自己受精後の植物の健康状態の回復が長期間続くことを実証し,浄化仮説を支持しています.

科学分野:

進化遺伝学の進化遺伝学について
集団遺伝学人口遺伝学
定量遺伝学定量遺伝学とは

背景:

近親交配はホモジゴス性を高め,有害なアレルに対する選択を強化します.
理論的なモデルは,近親交配が遺伝的負荷を浄化することを予測していますが,経験的なデータは稀です.
ネズミ,ドロソフィラ,家内ハエを対象とした以前の研究では,浄化のためのいくつかの証拠が示されました.

研究の目的:

インブリーディングが遺伝的負荷を浄化するという仮説を実証的に検証する.
インブリーディング中のフィットネス回復の時間経過を調査する.
実験結果を計算による予測と比較する.

主な方法:

自然に交配する植物の自己受精に関する実験.
インブリーディングの間,時間の経過とともに平均フィットネスを監視する.
遺伝的負荷と浄化ダイナミクスをモデル化するためのコンピュータシミュレーション.

主要な成果:

自己受精下で平均的なフィットネス回復の長期間経過を示した.
結果は,コンピュータ計算から得られた理論的な期待と一致しています.
観察された遺伝的負荷は,部分的にリセシブな有害アレルへの高い変異率を示唆しています.

結論:

インブリーディングは,有害な変異性アレルの集団を効果的に浄化する.
浄化プロセスとその後のフィットネス回復にはかなりの時間がかかります.
観察された遺伝的負荷を説明するために,部分的にリセッシブな有害アレルへの高い変異率が必要である.

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