High Functional Diversity in Mycobacterium tuberculosis Driven by Genetic Drift and Human Demography
For each site that underwent a mutation within MTBC we observed two states: the derived (or mutated) state, and the ancestral state. For synonymous and nonsynonymous mutations we deduced the ancestral state based on the sequence of the outgroup strain M. canettii. For the genomic deletions (originally described in ), the ancestral state is the non-deleted state and the deleted state is derived. The frequencies depicted here are those of the mutated states. All three types of mutations show similar frequency distributions, which suggests that most nonsynonymous mutations and deletions are not slightly deleterious but rather selectively neutral within MTBC. Blue, nonsynonymous mutations; red, synonymous mutations; yellow, genomic deletions.