Genetic structure of allopatric populations of Lutzomyia longipalpis sensu lato in Brazil.

Lutzomyia longipalpis sensu lato is a complex of phlebotomine sand fly species, which are widespread in the Neotropics. They have a great medico-veterinary importance due their role as vectors of Leishmania infantum, the causative agent of visceral leishmaniasis. Morphological variations of Lu. longipalpis s.l. males were reported in the late 1960s in Brazil. Male populations can present either one pair of spots on third abdominal tergites or two pairs on third and fourth ones, namely 1S and 2S phenotypes, respectively. Since then, there has been much interest on the taxonomic status of Lu. longipalpis s.l. Thereafter, several lines of evidence have been congruent in suggesting the existence of an uncertain number of cryptic species within Lu. longipalpis s.l. in Brazil. Herein, a 525 bp-fragment of the period gene was used for assessing the genetic structure and phylogenetic relationship of Lu. longipalpis s.l. populations in Brazil. We performed two set of analyses, first we originally sequenced three populations (Passira, Santarém and Teresina) of Lu. longipalpis s.l. and compared them. Thereafter, we performed a global analysis including in our dataset other three pairs of sympatric populations of Lu. longipalpis s.l. from three Brazilian localities available in GenBank. Fixed single nucleotide polymorphisms (SNPs) sharing, maximum likelihood inference, genetic structure and haplotype analyses revealed the presence of two genetic groups, one composed of Teresina population, and the other encompassing Passira and Santarém populations. The global analysis reflected the first of its kind, and two prominent groups were observed: the clade I comprising Teresina 1S, Bodocó 1S, Caririaçu 1S and Sobral 1S; and the clade II encompassing Passira 2S, Santarém 1S, Bodocó 2S, Caririaçu 2S and Sobral 2S. Genetic differentiation data suggested a limited gene flow between populations of the clade I versus clade II. Our results disclosed the presence of two prominent genetic groups, which could reasonably represent populations of Lu. longipalpis s.l. whose males produce the same courtship song.
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