Autocorrelation of normalized substitution rates r for the S. cerevisiae/S. paradoxus (a) and C. dubliniensis/C. albicans (b) pairwise analyses. The C. dubliniensis/C. albicans plot shows that substitution rates of neighboring genes are correlated up to 50 kb apart. This contrasts with the lack of correlation at any distance for the S. cerevisiae/S. paradoxus plot. Analogous graphs were produced for all fungal species pairs, and no significant autocorrelation was found, except for the C. dubliniensis/C. albicans and C. tropicalis/C. dubliniensis comparisons.