Geometria alar como estimador de variabilidade morfogenética de Aedes albopictus (Culicidae) do Estado de São Paulo

Abstract

Aedes albopictus is an important vector of etiological agents of diseases such as dengue, yellow fever and chikungunya responsible for epidemics and outbreaks. The high capacity of colonization and adaptation to different environments of this species makes it relevant for epidemiological studies. The high population genetic variability is a characteristic in mosquito vectors, since it results in rapid microevolution, adaptability to the human environment, resistance to insecticides and in other phenomena that greatly complicate the control of these vectors. As genetic variability has to be investigated by molecular approaches, which are expensive and time-consuming, we recently proposed an alternative way of estimating this variability: the ""MD"" (morphological diversity) index. This index uses geometry to quantitatively describe the degree of morphological diversity of population samples. The MD when calculated from morphological structures whose phenotype is inheritable, may retain partial correlation with genetic variability. Faced with this presumed correlation, it is reasonable to use MD as a practical preliminary substitute for traditional indexes of genetic variability (allelic richness, genotypic diversity, etc.). In this work we propose to compare the morphological diversity of five Aedes albopictus populations from four municipalities in the State of São Paulo (Campinas, Cotia, Santos and São Paulo). We hypothesized that populations would have different morphological variabilities due to different microevolutionary histories. In another hypothesis, the largest MD would be found in the sample of Santos, location of probable entry of exotic Ae. albopictus from their native Asian locations. The MD was obtained from morphometric data of the individuals wings, a heritable structure and a polygenic inheritance. The wings were submitted to standard methods of geometric morphometrics, including Procrustes overlapping and analysis of 18-point reference shapes. The main components of the shape variables of all the individuals sampled were plotted in two-dimensional graphs called ""morpho-space"", in which we can observe the degree of relative dispersion among the individuals, allowing the calculation of the centroid size of the set of individuals. In theory, the larger the centroid, the more scattered the points are and the more morphologically diverse the population is. The MD revealed that the population of Cotia was the most diverse, contradicting hypothesis II. However, it was a confirmed hypothesis, since the MD index pointed out differences in magnitudes of morphological differentiation between populations, validating a geometric morphometrics as a method capable of distinguishing geographic ones.