Patterns of genetic admixture in a naturally recolonizing American black bear population in Mississippi reveal changing connectivity in the lower Mississippi alluvial Valley, USA

American black bears (Ursus americanus) in the Lower Mississippi Alluvial Valley (LMAV) suffered significant declines in the 20th century from habitat loss and overexploitation. Remnant black bear subpopulations in southeastern Arkansas and eastern Louisiana have recovered and expanded into western Mississippi in the early 2000s. However, the genetic status and origin of subpopulations in Mississippi remain poorly understood. We evaluated genetic diversity, population structure, and connectivity of black bears in the LMAV and compared our results to a previous study. We identified an expanded admixture zone in western Mississippi where black bears dispersing from Arkansas and Louisiana converged and reproduced. The subpopulation in southern Mississippi exhibited the highest allelic richness (AR = 4.50) and elevated expected heterozygosity (HE = 0.61), consistent with recent admixture. Gene flow was greatest from the Tensas River Basin in Louisiana to the Mississippi subpopulations and to the Three Rivers Complex in Louisiana (m = 0.17–0.22), suggesting corridors between Mississippi and Louisiana may be similar in quality to corridors among Louisiana subpopulations. However, dispersal into Arkansas from all subpopulations remained limited, underscoring the genetic isolation of the White River Basin and West Gulf Coastal Plain subpopulations. Our results revealed an undocumented dispersal pathway from Louisiana’s Upper Atchafalaya River Basin into southern Mississippi. Despite these promising findings, genetic diversity in Mississippi and the LMAV remains lower than in many other black bear populations. Continued habitat restoration, improved corridor connectivity, and ongoing genetic monitoring are essential to support black bear recovery in Mississippi and across the LMAV.