Mitochondrial COI reveals pronounced geographic structuring and limited gene flow in global Aedes aegypti populations

Aedes aegypti is a major vector of several arboviral diseases, and understanding its global genetic diversity is critical for effective control strategies. The mitochondrial cytochrome c oxidase subunit I (COI) gene is widely used in population genetics due to its relatively rapid mutation rate and maternal inheritance. This study analyzed 480 mitochondrial cytochrome c oxidase subunit I (COI) gene sequences from five continents (Africa, Asia, Europe, North America, and South America) to investigate genetic diversity, population structure, and phylogeographic patterns. A total of 96 haplotypes, 197 polymorphic sites, and 214 mutations were identified. High global haplotype diversity (Hd = 0.934) and nucleotide diversity (π = 0.08596) indicate substantial genetic variation. Africa exhibited the highest haplotype diversity, while Asia showed the highest nucleotide diversity. The haplotype network revealed 83 unique haplotypes and only 13 shared haplotypes, including a globally distributed lineage (Hap_9), suggesting both local diversification and long-distance dispersal. Phylogenetic analysis revealed two weakly supported clades, with most haplotypes forming a single mixed cluster, indicating limited phylogeographic structure. However, population genetic analyses showed significant differentiation among continents (FST = 0.18789, P < 0.001), with most variation occurring within populations (81.21%). Moderate gene flow (Nm = 1.08), together with a weak but significant isolation-by-distance pattern, further indicates partial connectivity among populations. Overall, the results highlight a complex global genetic landscape shaped by historical dispersal, human-mediated movement, and regional evolutionary processes. These findings provide valuable insights for improving vector surveillance and control strategies worldwide.