Fig. 4: Phylogeographic analysis of the 2.MED3.1.2 subgroup.

a The maximum clade credibility tree of the Y. pestis 2.MED3.1.2 subgroup, based on 143 SNPs, with nodes color-coded by sampling locations. The inset in the top-left corner shows the posterior probabilities for the inferred source locations. Geographic abbreviations for strain isolation locations are detailed as follows: Uppercase abbreviations denote provinces, including the Inner Mongolia Autonomous Region (NMG) and neighboring provinces of Ningxia Hui Autonomous Region (NX), Shaanxi Province (SX), and Hebei Province (HB) in China, along with Zamyn-Uud (ZMWD) in Mongolia’s Dornogovi Province. Lowercase abbreviations denote cities within Inner Mongolia, including Xilingol League (Xlglm), Ulanqab City (Wlcbs), Chifeng City (Cfs), Baotou City (Bts), Hohhot City (Hhhts), BayanNur City (Bynes), Erdos City (Eedss). b Transmission dynamics of the 2.MED3.1.2 subgroup, with the direction of spread indicated by arrows. Dashed and solid lines differentiate between long-distance and short-distance transmissions, respectively. Region labels are shaded with colors corresponding to those in panel (a). Color-coded lines represent the timeline of spread, with darker colors denoting more recent events. An additional inset in the bottom-right provides a full map of Inner Mongolia and adjacent provinces. c Migration histogram for the 2.MED3.1.2 subgroup, showing both inward and outward migrations for highlighted regions.