FIG. 3.—

Maximum parsimony haplotype network for a 236-bp segment of the Brevinin1.1 locus. White circles represent Rana pipiens haplotypes, gray circles represent Rana blairi haplotypes, and black circles represent Rana palustris haplotypes. Gray squares represent inferred nodes that were not observed. The size of the circles indicates the frequency of each allele in the respective species. Nonsynonymous substitutions are indicated by small black rectangular bars, and synonymous substitutions are indicated by small white rectangular bars; thus, branch lengths represent the total number of substitutions. Common alleles are labeled. Allelic lineages are surrounded by large rectangles. Highly divergent alleles, separated mostly by nonsynonymous substitutions, occur in both R. pipiens and R. blairi, causing several tests of selective neutrality to be significant (table 1). A haplotype is shared between R. pipiens and R. palustris, indicated by a white circle superimposed on a black circle. A pattern of both very common and very rare alleles can be seen, especially for the Lineage 1 lineage in R. pipiens, suggestive of a recent rapid increase in allele frequency.