Summary of transition bias in mutational events per antibiotic in the Basel and Manson data sets.

Rows are ordered by decreasing number of events in the Basel data set. Dashes indicate antibiotics for which there are no mutational events in the respective data set. Mutations that confer resistance to multiple antibiotics are reported separately and were not counted among the events conferring resistance to individual antibiotics. P values indicating deviation from the default null model and three revised null models (1: the default null model, 2: accounting for path-level bias, 3: accounting for jackpot mutations, and 4: accounting for both path-level bias and jackpot mutations; see main text). Significance (P < 0.05) is indicated for each test by the number of the corresponding null model (e.g., 1, 2 indicates statistical significance for null models 1 and 2).