Extended Data Figure 4.

Ancestral node location posterior probabilities (ANLPP), for nodes A, B and C, estimated using the complete dataset (top row) and ten replicate subsampled data sets (other rows). See Methods for details. ANLPPs were calculated using two approaches: DTA=discrete trait analysis method³⁰ (left side columns) and BASTA=Bayesian structured coalescent approximation method²⁹ (right side columns). For each method, we employed an asymmetric model of location exchange to estimate ancestral node locations and to infer patterns of virus spread among regions.