FIG. 22.10 Co-speciation. Parasites and their hosts often evolve together, and the result is similar phylogenies. Sources: Data from J. P. Huelsenbeck and B. Rannala, 1997, “Phylogenetic Methods Come of Age: Testing Hypotheses in an Evolutionary Context,” Science 276:227, doi: 10.1126/science.276.5310.227; Louse photo by Alex Popinga, courtesy of James Demastes; pocket gopher photo by Richard Ditch @ richditch.com.