Effect of rate constancy on bootstrap support for Coelomata in four-taxon analysis. Graphs show results before application of tests (left, 0-level) followed by increasing stringency (5, 10, 40% significance) of the chi-square test  (circles) and Z-test  (triangles); the 5% level is normally used. (A) number of proteins passing rate constancy at each cutoff level. (B) relative nematode branch length upon concatenation of all rate constant proteins at each level. (C) bootstrap support for Coelomata for each rate-constant concatenation.