Fig. 6

A Pi of the mtDNA of 25 Anser spp.. A sliding window test with 500-bp windows and 50-bp steps annotated 10 mutation hotspots. The X-axis depicts genomic regions, while the Y-axis shows Pi values. The grey bars represent the threshold lines for the top 10 regions with relatively high Pi values. B Analysis of selection pressure. Density distribution of Ka, Ks, and Ka/Ks for homologous PCG pairs of the mtDNA of 25 Anser spp