: Globally, the disfiguring, cutaneous form of leishmaniasis produces 20-40 million human cases and is transmitted exclusively by the bite of infected phlebotomine sand flies. Leishmaniasis is endemic throughout the New World tropics, and it is now increasing noticeably in rural, forested and suburban settings. A second sand fly-vectored disease, bartonellosis, is a scourge of the South American Andes with cases concentrated in Peru--it has a high fatality ratio >80% in untreated cases. The current proposal focuses on the 28 sand fly species of the Verrucarum group (in the genus Lutzomyia), which includes at least 17 known or suspected vectors of one or more of these diseases.
The specific aims are as follows: (1) To compare the population genetic structure of 2 of the most widely distributed members of the Verrucarum group, Lutzomyia verrucarum (bartonellosis vector) and Lutzomyia serrana (probable cutaneous leishmaniasis vector), in order to detect cryptic species and evaluate the relative significance of geographic barriers and linear distance to genetic differentiation using variable mitochondrial gene sequences (cytb). (2) To investigate genetic relatedness among morphologically almost identical species (6 species of the s. townsendi and 2 species of the s. serrana) using total evidence approaches--DNA sequences, hybridization and isoenzymes. (3) To infer a molecular phylogeny for species of the Verrucarum group and related subgenera, and genera, based on comparison of mitochondrial (12SrDNA, COl) and nuclear gene sequences (18SrDNA, 28SrDNA, and ITS2). (4) To use the inferred phylogeny for verifying morphologically defined species, series, subgenera, and genera definitions, by testing their monophyly. (5) To deduce the evolutionary history of geographical and ecological associations of this group of taxa. (6) To develop molecular tools for a rapid identification of sand fly taxa. Resolution of these aims will provide insights into sand fly population genetic structure, and effects of geographic isolation. It will test if morphological classifications are justified by phylogenetic history. From the suite of genetic profiles generated, species identification and species authenticity will be facilitated. The phylogenetic relationships of a large and medically important group, Verrucarum, will be clarified. A broader perspective to the relationships among the nearly 400 species in the genus Lutzomyia will be established. A better understanding of the taxonomic and phylogenetic relationships provided by these analyses will lead directly to more realistic assessments of disease risk and new insights into the nuances of environmental effects on sand fly evolution.
