Fig. 4

Characteristics of gSNP, nfSNP and dSNP in the coding region: (a) Comparison of the distribution of non-synonymous and synonymous SNPs in derived mutations (allele frequency <0.5) of gSNP, nfSNP, and dSNP sites, respectively. b Distribution of SNPs occurred at the first, second and third position of a codon in derived mutations of gSNP, nfSNP and dSNP sites, respectively. c Comparison of non-synonymous and synonymous SNPs distribution in ancient mutations (allele frequency ≥0.5) of gSNP, nfSNP and dSNP sites, respectively. d Distribution of SNPs occurred at the first, second and third position of a codon in ancient mutations of GNP, nfSNP and dSNP sites, respectively, in which the total frequency is 1 for each category of SNPs in a-d