顯性遺傳對於維持穆氏擬態中多態性的影響
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| photo: what-when-how.com |
標題：The effect of dominance on polymorphism in Müllerian mimicry
摘要
Dominance controls the phenotype of heterozygous individuals, and plays an important role in the maintenance of polymorphism. Here we focus on the dominance acting on warning-pattern polymorphism in species engaged in Müllerian mimicry. Müllerian mimics are toxic species which display bright colour patterns used as a warning signal to predators and are subject to local positive density-dependent selection. Some Müllerian mimics are polymorphic due to a selection/migration balance in spatially heterogeneous communities of prey. Since heterozygotes at a locus controlling warning pattern might exhibit intermediate, non-mimetic heterozygous morphs, dominance is likely to influence the polymorphism at this locus. Using a deterministic model describing migration, density-dependent predation and reproduction, we investigated the influence of dominance on the dynamics of alleles at locus determining mimetic phenotype. Our results suggest dominance may interact with migration and selection and plays an important role in shaping the conditions of polymorphism persistence and the frequency of alleles at this locus. Our results thus highlight the important role of dominance in the dynamics of polymorphism at loci under balancing selection due to environmental heterogeneity.
有些穆氏擬態物種多態性的產生與維持，一直是個吸引科學家的問題，雖然已經從很多個方面討論，但總很難有個結論，主要是因為要解釋斑紋的有效性與不同斑紋的族群間的平衡來自多重複雜的因素，並且因素間可能有交互作用，很不容易從一而論，解釋所有的情況。
這個研究的目的是想從遺傳學的角度著手，解釋顯性遺傳在穆氏擬態多態性的維持上的重要性。如果穆氏擬態的多態性來自不同斑紋族群遷徙時的雜交，那麼控制這個斑紋的基因座(locus)的顯隱性必然影響斑紋性狀的表現，當兩個族群雜交時就會出現中間型 (intermediate forms)，又因為只有顯性的斑紋可以表現在斑紋上，演化的歷程中就可能根據這些顯性表型逐漸的影響讓基因頻率轉移，進而產生新的斑紋。
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| 本篇所使用的數學模型的一部分 |
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| Fig. 2 假設一個對偶基因ab在不同的狀況下的模擬結果。 灰：多態型維持 白：a被固定 黑：b被固定 A：全隱性 B：部分隱性 C：共顯性 D：全顯性 |
說實在的，這真是篇讓人看完頭很痛的文章......
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