he diversification rate for the study sequences were examined using a birth–death model (Nee et al., 1994) to obtain information about speciation and extinction of HCV 3a in Pakistan employing the ape (Paradis et al., 2004) and laser (Rabosky, 2006) packages in R (version 2.15.3, http://www.R-project.org) to calculate the gamma statistic (Pybus and Harvey, 2000) and fitting models with continuous time varying speciation/extinction rates with the fitEXVAR function (Rabosky and Lovette, 2008).