Seasonal Variation and Sexual Shape Dimorphism in Wings of the Neotropical Hairstreak Strymon davara (Lycaenidae, Theclinae, Eumaeini)

The northern valleys of the Atacama Desert in Chile have minimal seasonal variations of temperature, which enable continuous growth of many plants and their associated phytophagous insects. This is the case in the Neotropical hairstreak Strymon davara (Lepidoptera, Lycaenidae, Theclinae, Eumaeini), whose larvae are able to develop throughout the year on the inflorescences of their only host plant, Althernanthera halimifolia (Amaranthaceae). Although minimal, environmental seasonal variations could have some effect on the development of highly sensitive organisms. The first geometric morphometrics study of the wings of S. davara was intended to test for seasonal changes in the morphology. The same tools were used to assess for wing sexual dimorphism in this Neotropical hairstreak. Fifteen and 14 landmarks were selected on the fore and hindwings, respectively, of male and female adults collected in winter and summer in the Azapa Valley, northern Chile. The principal component analysis of wing shape shows that the variation was mainly distinguished by sexual dimorphism at the first dimension (PC1) and mostly by season at the second dimension (PC2). This variation might be a plastic response to subtle seasonal variation in environmental conditions and due to sexual niche divergence and behavior of male and female butterflies.