Fig. 2
Characterization of selection forces in different structures of genes. A Distribution of the pairwise fixation index (FST) (x-axis), XP-CLR score (y-axis), and value of ROD (color) between wild-type and domesticated ducks. The dashed vertical and horizontal lines indicate the significance threshold (FST > 0.31, ROD > 0.668, XP-CLR > 6.685) used for extracting outliers. B Difference test of FST in different structures of 781 protein-coding genes in genome selected regions. The level of significance is presented as ns (not significant), *(P < 0.05), or ***(P < 0.001). C Distribution patterns of FST in different structures of gene model, including upstream 4-kb region, gene body, and downstream 4-kb region. The blue solid line represents the mean value of FST for 781 putative selected genes, and the dashed line represents the gene transcription start site and transcription termination site. The gene body region on the x-axis does not represent the actual sequence length; each gene is scaled according to the sequence length. D The distribution of the degree of nucleotide diversity loss in mallard and domesticated duck populations was calculated using the same genetic model of Fig. 2C