Population genetic analyses were conducted using samples of Aedes aegypti from 14 localities in the north, southeast, northeast, and central regions of Brazil. An 852-bp region of the mitochondrial DNA cytochrome oxidase I (COI) gene was used in the analyses. Ten haplotypes were observed, and cluster analyses revealed 2 groups (lineages) separated by 8 fixed mutations, suggesting that the Brazilian Ae. aegypti populations probably came from East and West Africa, with evidence of multiple introductions, one related to Group 1 and two related to Group 2. Considering all samples, genetic and geographic distances were significantly correlated (r2 = 0.332; P = 0.038), supporting the isolation by distance (IBD) model, but no correlation was detected for any particular region, which is consistent with human migrations and trade exchanges. Genetic distances (pairwise FST and Nm values), AMOVA, and cluster analyses indicated a deep genetic structure for the Brazilian Ae. aegypti, probably resulting from several factors: multiple introductions associated with distinct lineages, geographic differentiation (IBD), passive dispersal patterns, control activities, extinction and recolonization events, and genetic drift. Copyright © 2008 by The American Society of Tropical Medicine and Hygiene.
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