Some Statistical Parameters in Molecular Evolution and Their Application

The precise evolution relationship and phylogenetic tree can be obtained with the aid of analyses and calculations of certain gene data. Some statistical parameters of molecular evolution were introduced and their application was explained, including K_a (nonsynonymous nucleotide substitutions), K_s (synonymous nu-cleotide substitutions) and K_a/K_s. The other important parameters, for example DNA polymorphism and genetic distance, were also discussed. Based on these evolution statistical parameters, the positive selection and gene evolution speed could be determined. An example was used to reveal the evolution mechanism of plant resistant genes with analyses of three parameters.