Phylochronology of Parnassius species based on ITS1 and ITS2 data under a Bayesian relaxed clock analysis (BEAST, version 1.8.3). C1, C2: calibration points (see text section: Divergence time estimation). Numbers and numbers in parentheses at nodes: median time estimates and 95% confidence interval (CI) in million years ago (Ma), respectively. The red and black bars: different populations within species. Lower graph: The main global temperature curve (Zachos et al. 2001) from the late Oligocene to the Pleistocene with palaeoclimatological information (monsoon and related Central Asian aridification) (from Favre et al. 2015).