Abstract

Chagas disease is one of the main zoonoses mediated by vectors in America. The etiological agent is the protozoanTrypanosoma cruzi, transmitted mainly by hematophagous insects of the subfamily Triatominae.Mepraiaspecies are triatomines endemic to Chile that play an important role inT.cruzitransmission in the wild cycle and are potential vectors for humans. In addition to the continental distribution, populations ofMepraiagenus have been reported inhabiting islands of northern Chile. The presence of individuals ofMepraiain insular areas might be explained through passive dispersion by marine birds or by vicariance of an ancestral widespread population. To clarify the biogeographic origin and phylogenetic relationships of island individuals ofMepraia, mitochondrialCOIandcyt bgenes were sequenced in individuals from island and continental areas. Gene sequences were used to estimate phylogenetic relationships, divergence dates and migration rates between insular and continental populations. The dates of divergence estimates are congruent with sea level and tectonic changes that originated the islands during Pleistocene. Migration rates suggest symmetric historical island-continent gene flow. We suggest that the origin of island triatomines can be explained by both vicariance and dispersion. Phylogenetic relationships show that individuals from Santa Maria Island and the continent clustered in a clade different from those previously reported, indicating a new lineage ofMepraiagenus. This study will contribute to understand the origin of theT.cruziinfection in coastal islands of northern Chile.