Speciation and population structure in the morphospecies Lutzomyia longipalpis (Lutz & Neiva) as derived from the mitochondrial ND4 gene.

Recent studies have suggested that the phlebotomine sand fly Lutzomyia longipalpis (Diptera: Psychodidae), the principal vector of visceral leishmaniasis in the Neotropics, may consist of several allopatric sibling species. Phylogenetic and population genetic analyses of nucleotide variation in a 618-bp fragment of the mitochondrial ND4 gene were carried out on specimens of Lu. longipalpis from several locations in Central and South America. The analyses were concordant with previous findings, indicating that certain allopatric populations of Lu. longipalpis have become sufficiently differentiated as to represent sibling species. Phylogenetic analyses revealed deep genetic divisions between four clades represented by specimens from northern South America, Brazil, Central America, and an isolated Colombian population. Strong differentiation also was observed between certain populations within the first two clades. Partitioning of genetic diversity within and between Central American populations did not show the presence of more than one species in the region. However, distance, even within the 70-km range of the Honduran collection sites, was found to have a remarkably strong effect on gene flow. The highly subdivided population structure may be due to the patchiness of their distribution. F(ST) values comparing a Guatemalan population with several Honduran populations revealed a level of differentiation associated with a negligible rate of gene flow.