Maximum clade credibility Bayesian tree and haplotype network of mitochondrial DNA. Branch support values higher than 0.80 are shown above nodes. Each circle represents a haplotype, and the size of the circle is proportional to that haplotype’s frequency. Dots represent unsampled haplotypes. Haplotypes are coloured according to taxon: black for Aegithalos bonvaloti and white for A. fuliginosus. H2 is the most widely distributed haplotype shared by 19 individuals of A. fuliginosus and 5 individuals of A. bonvaloti.