Estimations population dynamics of 2009 H1N1 viruses and their closest related swine viruses. Green, blue and yellow shows HA, NA and PA, respectively, which represented three different origins, especially as classical, Eurasian and avian-to-swine reassortant swine sublineages. Population dynamic estimates for classical, Eurasian and avian-to-swine reassortant swine sublineages can be found in Additional file 5. X-axis: time in years before present; Y-axis: estimated population size [units = Neτ, the product of effective population size and generation length in years (log-transformed)]. The median estimate and both 95% HPD limits are indicated.