Figure 4.

Phylogenetic tree of the six mitochondrial and cytosolic carbonic anhydrase isozymes of human and mouse. Sequences are as in Hewett-Emmett and Tashian (3), except human CA VB (16), mouse CA VB (this study), and mouse CA VII (32). The five gene duplications (1, 2a, 2b, 3a, 3b) are boxed. Branches are drawn to scale, their lengths representing percent of sites in the protein alignment replaced after Poisson correction for undetected multiple hits (cf. Kumar et al., ref. 28). Numbers beside each node represent percent of 1,000 bootstrap replicates supporting that particular grouping, e.g., 98% of the bootstrap resamples place the human and mouse CA I, CA II, and CA III sequences in a single group. Duplications 2a and 2b, and 3a and 3b are separated by short branches and low bootstraps (68% and 61%), and there is no statistical support for the order of the duplications and for the duplications occurring sequentially rather than at the same time.