Fig. 3. Estimated effective migration surfaces (EEMS) at different population scales.

a Map of EEMS for the entire species. Estimated effective migration rates (m) are mean centred on a log₁₀ scale. A value of 1 equates to a tenfold rate increase over population average, ranging from areas of low (brown) to high (blue) m. The intensity of the colours represents the relative difference from the population mean rates. Point diameter is proportional to the number of individuals sampled in a given deme (range = 1–72). Solid black lines indicate areas where the posterior probability of m differing from the mean rate is >95 percent and the dashed lines highlight areas that are >90 percent. These can be interpreted as significant effective ‘barriers’ to migration in brown areas and significant effective ‘corridors’ for migration in the blue areas. Two significant effective barriers were present: one corresponding to Gashaka and Mbe (Nigeria) and another originating from Gishwati (Rwanda) and shared with its nearest neighbours. These are localized areas of high differentiation, and when we excluded Mbe and Gishwati from the dataset, these barriers were no longer significant (Extended Data Fig. 6a, c). Notably, historical effective barriers separating the subspecies’ ranges were not detected. Effective migration rates within much of Pan troglodytes verus were significantly higher than average. b Historical EEMS map of P. t. verus. There was a significant barrier associated with Mt. Sangbé in Côte d’Ivoire. When we removed Mt. Sangbé the barrier was no longer significant, but it was still present, suggesting the possibility of reduced historical gene flow across Côte d’Ivoire. c Historical EEMS map of P. t. ellioti, P. t. troglodytes and P. t. schweinfurthii (collectively ETS). As in a, removing Gishwati resulted in the barrier no longer being significant (Extended data Fig. 6c). Rates of m between the panels are relative and not directly comparable.