ML phylogeny of Mustelidae showing reconstruction of ancestral areas based on the four-state analysis. Pie charts at nodes show proportional likelihoods that the common ancestor was distributed in Africa (purple), Eurasia (red), North America (blue) or South America (green). Proportional likelihood values and associated significance levels for ancestral area reconstructions are presented in Additional file 3. Taxa are colored according to their coding states (see legend). * = occurs in Eurasia and North America; + = occurs in North America and South America; # = occurs in Africa and Eurasia.