FIG. 3.

Twenty perA alleles cluster into four major groups. A phylogenetic tree constructed by the neighbor-joining algorithm based on the Kimura two-parameter model of nucleotide substitution is shown on the left. Bootstrap values for the major groups based on 500 replications are given at the internal nodes. To the right is a graph of the locations of the 46 polymorphic amino acid sites (274 total), which are marked as vertical lines that indicate differences from the consensus of all 20 alleles.