Evolutionary view on sexual dimorphism and shape variation in Iranian populations of Hypera postica (Coleoptera: Curculionidae)

摘要

The alfalfa weevil (Hypera postica) is a worldwide variable pest that is established in almost all Iranian alfalfa fields. As a result of the large distribution range and the climatic diversity in Iran, population differentiation had been observed, which was largely unstudied. Previous morphological studies have suggested a local adaptation of Hypera postica populations; yet, traditional morphological markers are not powerful enough to reveal subtle changes in morphological characters among populations or even gender within populations. The robust statistical geometric morphometric analysis promised to be able to detect small changes in shape. In this study, we used Fourier outline analysis to compare the shape of pronotum, elytra and rostrum of five Iranian populations of the alfalfa weevil from three well-separated geographic areas (Karaj, Jovein and Tuyserkan). Besides population divergence, the sexual shape dimorphism was investigated. The results show a significant shape difference between males and females, at inter- and intrapopulation levels for H. postica. These results suggest the influence of a local natural selection on the studied characters.