Rift Valley fever virus M segment maximum a posteriori clade credibility tree, MCMC chain length 9.0 × 10⁷ steps, 2.25 × 10⁶ steps (25%) removed as burn-in. Posterior support values (highest posterior density, HPD) are indicated as integers (i.e., 100% support = 1.0) above each node respectively. The calculated mean times to the most recent common ancestor (TMRCA) are indicated below each respective node and are enumerated as years before the collection date of the last outbreak specimen (May, 2007). The 2006–2007 Kenyan outbreak specimen M segment reassortant (strain #0608) is indicated by an asterisk. Adapted from [21]. (A color version of this figure is available online at www.vetres.org.)