Population genetic analysis of human-chicken conserved sequences. Frequency spectra of non conserved coding (CDS) and non coding (NC) SNPs and of these conserved with more than 80% identity (cCDS and cNC), in bins of 3 alleles. B and C: Rare alleles (1 to 3 occurrences) frequency in different conservation classes, for all, coding or non coding sequences. The counts of rare and frequent alleles (>3 occurrences) were compared using the exact Fisher's test. The genotyped panel  includes 71 individuals (= 142 alleles).