Bayesian phylogenetic tree of individuals (A) and median-joining haplotype network (B) of Bombus based on COI mtDNA sequences. The tree was rooted with B. mesomelas. Numbers along branches in the phylogenetic tree indicate support (posterior probability; provided only for major clades). Within the network, sizes of circles are proportional to haplotype frequency and lines across branches represent mutational steps between haplotypes. The color of circles in the network indicates species in which the haplotype was found.