Drivers of molecular and morphometric variation in Triatoma brasiliensis (Hemiptera: Reduviidae): the resolution of geometric morphometrics for populational structuring in micro-geographic scale

Abstract Background The protozoan Trypanosoma cruzi circulates in semiarid areas of the northeastern of Brazil in distinct ecotopes (sylvatic, peridomestic and domestic) where Triatoma brasiliensis is the most important Chagas disease vector.Methods We sampled populations of T. brasiliensis from distinct ecotypic and geographic sites in the Rio Grande do Norte (RN) and Paraíba (PB) States to compare the results of morphometric and genetic variations. The geometric morphometry was carried out with 13 landmarks on the right wings ( N =698) and the genetic structure was assessed by sequencing a region of cytochrome B mitochondrial gene ( N =221). Mahalanobis distance (DM) and molecular differentiation coefficient (Φ ST ) were calculated among all pairs of populations.Results The results of comparisons generated MD and Φ ST dendrograms, and graphics of canonical variate analysis (CVA). Little structure was observed for both markers for macro-geographic scales. Mantel tests comparing geographic, morphometric and genetic matrices showed low correlation (all R 2 <0.35). The factorial graphics built with the CVA evidenced population delimitation for the morphometric data at micro-geographic-scales.Conclusions We believe that T. brasiliensis carries in its genotype a source of information to allow the phenotypical plasticity across its whole distribution for shaping populations, which may have caused a lack of population delimitation for CVAs in morphometric analysis for macro-geographic scale analysis when populations are grouped. On the other hand, the pattern of morphometric results in micro-geographic scales highlights the potential of this tool to infer the source for infestation.