Fig. 4

Demographic history of the pygmy right whale inferred using the PSMC framework. The model covers the last 10 Mya to 100 kya and is scaled based on a mutation rate of 1.38 × 10⁻⁸ per site per generation [20] and a generation time of 22.1 years, using the minke whale as an approximation for the unknown life expectancy [34]. x-axis depicts the time in number of years ago while the y-axis depicts the effective population size in thousand individuals. The model indicates a peak of effective population size around the Late-Pleistocene Transition (LPT, 2.6 Mya) (light blue), followed by a steady decline until reaching a lower, but stable population size after the Mid-Pleistocene Transition (MPT, 1 Mya–700 kya) (dark blue). Interglacial periods (gray) did not influence stock sizes