Search for a command to run...
Aedes vexans (Meigen) (Diptera: Culicidae) is a globally distributed floodwater mosquito and an important vector of zoonotic arboviruses affecting wildlife, livestock and humans. Despite its broad range, continental-scale population genetic patterns in North America remain poorly characterized. We analyzed a 443-bp fragment of the mitochondrial ND5 gene from 499 Ae. vexans specimens collected across 15 states in the United States (U.S.) to assess genetic diversity, population structure, and demographic history. We identified 179 haplotypes, most of which were singletons, and haplotype diversity (Hd) was uniformly high across states and regions (overall Hd = 0.926). Nucleotide diversity was low to moderate (p = 0.010), consistent with numerous closely related maternal lineages. Tajima's D values were negative for most states and all geographic regions, and significantly negative for Kansas, Louisiana, the north-central and south-central regions, and the full dataset, indicating an excess of rare variants consistent with recent population expansion. Population differentiation was minimal: Wright's F-statistic (FST) among the four regions (western, north-central, south-central, and eastern) ranged from 0.009 to 0.038, demonstrating extensive gene flow and very weak mitochondrial population structure across the U.S. Together, these findings indicate that Ae. vexans shows very weak mitochondrial population structure at continental scales, with widespread maternal gene exchange and few barriers to dispersal. This study provides the first broad-scale genetic assessment of Ae. vexans in the U.S. and establishes a baseline for future work incorporating nuclear markers, expanded global sampling, and temporal datasets to resolve patterns of connectivity and evolutionary dynamics in this widespread mosquito.