Ultrametric tree showing phylogenetic relationships and estimated divergence ages among studied gibbon individuals based on complete mitochondrial cytb sequence data. For individual codes see Additional File 1. Circles indicate bootstrap or posterior probability values (filled circles: >90%, >0.95, open circles: <70%, <0.80). Nodes of interest are arbitrarily numbered (N1-N45). C2 and C3 refer to two of the three nodes used for calibration (C1 not shown). Light green bars indicate the four radiations. A geological time scale is given below. Full details of age estimates and node supports are presented in Table 2.