Estimates of regional brown rat range expansions based on pairwise ψ statistics: (A) eastern Asia; (B) SE Asia and the Middle East; (C) Europe; (D) western Europe and the Expansion range; and (E) Russia, the Aleutian Archipelago, and Western North America. Lines show directionality from inferred source (pink) to sink (yellow) populations, whereas thickness was scaled to the Z-score when the absolute value was greater than five.