We inferred the evolutionary rates and past population dynamics of class II aPMV-1 using a Bayesian coalescent approach [41] . This analysis was based on all full length genome sequences in the data set which had a date of isolation and excluded the six recombinant sequences. Bayesian estimates of the evolutionary rates of each gene and concatenated coding genome of class II aPMV-1 were between 0.98610 23 -1.56610 23 substitutions/site/year (Table 1 ). Evolutionary rate estimates under a relaxed clock with HKY+G 4 (Table S4 ) and GTR+G 6 ( Table 1) substitution models were consistent. The time to the most recent common ancestor (TMRCA) of class II aPMV-1 was estimated to be between 114 and 137 years before 2005, or between year 1868 and 1891. Bayesian skyline plots (BSP) were used to infer how effective population size has changed with time [41, 42] . All six protein-coding genes and the concatenated genome maintained constant effective population size until the late 1990's ( Figure 5A ). In 1997-8 there was an abrupt decline in the population with recovery from this event in the early 2000.