Adaptive evolution in humans revealed by the negative correlation between the polymorphism and fixation phases of evolution.

ABSTRACT: The selective forces acting on amino acid substitutions may be different in the two phases of molecular evolution: polymorphism and fixation. Negative selection and genetic drift may dominate the first phase, whereas positive selection may become much more significant in the second phase. However, the conventional dichotomy of synonymous vs. nonsynonymous changes does not offer the resolution needed to study the dynamics of these two phases. Following previously published methods, we separated amino acid changes into 75 elementary types (1-bp substitution between their respective codons). The likelihood of each type of amino acid change becoming polymorphic (PI, which stands for "polymorphic index"), relative to synonymous changes, can then be calculated. Similarly, the likelihood of fixat

SUBMITTER: Gojobori J 

PROVIDER: S-EPMC1820682 | biostudies-literature | 2007 Mar

REPOSITORIES: biostudies-literature