Fig. 3.

Distribution of Schlafen sequences among taxa. The topology and divergence times of the mammalian tree are drawn according to www.tolweb.org/tree and Murphy et al. (2007). The total numbers of Slfn sequences for each taxon are indicated, as well as the number of Slfn sequences that fell within each of the four groups identified in our phylogenetic analyses (Fig. 4, Fig. 5). Only sequences that were suitable for our phylogenetic analyses (see Methods) could be classified into one of the 4 groups. Genome sequencing status at the time of this analysis: ⁎2× (or less) whole genome shotgun; ^†underway, sequencing projects at early stages.