In genetics, the Ka/Ks ratio (or ω, dN/dS), is the ratio of the rate of non-synonymous substitutions (Ka) to the rate of synonymous substitutions (Ks), which can be used as an indicator of selective pressure acting on a protein-coding gene. Comparisons of homologous genes with a high Ka/Ks ratio are usually said to be evolving under positive selection. Methods for estimating Ka and Ks can be classified into two groups: approximate methods and maximum-likelihood methods.

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dbpprop:abstract
  • In genetics, the Ka/Ks ratio (or ω, dN/dS), is the ratio of the rate of non-synonymous substitutions (Ka) to the rate of synonymous substitutions (Ks), which can be used as an indicator of selective pressure acting on a protein-coding gene. Comparisons of homologous genes with a high Ka/Ks ratio are usually said to be evolving under positive selection. Methods for estimating Ka and Ks can be classified into two groups: approximate methods and maximum-likelihood methods. Approximate methods involve three basic steps: counting the number of synonymous and nonsynonymous sites counting the number of synonymous and nonsynonymous substitutions, and correcting for multiple substitutions. The maximum-likelihood approach uses the probability theory to finish all three steps in one go.
  • 在遗传学中，Ka/Ks或者dN/dS表示的是异意替换（Ka）和同意替换（Ks）之间的比例。这个比例可以判断是否有选择压力作用于这个蛋白质编码基因。异意替换导致氨基酸的改变，而同意替换由于密码子虽然改变，但是仍旧对应的是同一氨基酸，所以是“同意”。 由于异意替换往往对于生命体有害，所以在纯化选择的作用下，异意替换常常会在群体中被逐渐消灭。
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  • In genetics, the Ka/Ks ratio (or ω, dN/dS), is the ratio of the rate of non-synonymous substitutions (Ka) to the rate of synonymous substitutions (Ks), which can be used as an indicator of selective pressure acting on a protein-coding gene. Comparisons of homologous genes with a high Ka/Ks ratio are usually said to be evolving under positive selection. Methods for estimating Ka and Ks can be classified into two groups: approximate methods and maximum-likelihood methods.
  • 在遗传学中，Ka/Ks或者dN/dS表示的是异意替换（Ka）和同意替换（Ks）之间的比例。这个比例可以判断是否有选择压力作用于这个蛋白质编码基因。异意替换导致氨基酸的改变，而同意替换由于密码子虽然改变，但是仍旧对应的是同一氨基酸，所以是“同意”。 由于异意替换往往对于生命体有害，所以在纯化选择的作用下，异意替换常常会在群体中被逐渐消灭。
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  • Ka/Ks ratio
  • Ka/Ks
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