Figure 2.
Association between level of genetic drift and genome size (A) and gene density (B) for the 42 pairs of bacterial genomes. The level of genetic drift exhibits a strong negative correlation with genome size (r = –0.72, P = 6.3 × 10−8). When only strictly free-living bacteria are considered, the correlation remains statistically significant (r = –0.55, P = 0.039), particularly when the anomalous pair of cyanobacteria is excluded (r = –0.86, P = 0.0018; see Results for explanation).
