Description of datasets. (a) Phylogenetic comparison of sequences from experimental evolution experiments (left) and sequences sampled from nature (right), all drawn to the same scale. Whereas the SSRV-A (32 years), MSV-F (6 years) and MSV-B (6 years) datasets are described here for the first time, the MSV-B (5 years), MSV-A, and WDV datasets are those described by van der Walt et al. , Varsani et al.  and Ramsel et al. , respectively. Black dots indicate likely rooting positions as determined by an outgroup. Best fit models used during maximum likelihood tree construction are GTR+I+Γ4 for the SSRV, WDV and MSV-A trees, F81+Γ4 for the MSV-B five-year and MSV-F six-year trees and TN93+Γ4 for the MSV-B six-year tree. (b) Evolution experiment datasets indicating the sources and timing of sequence sampling.