A Geometric Morphometric Study of the Wing Shapes ofPieris rapae(Lepidoptera: Pieridae) from the Qinling Mountains and Adjacent Regions: An Environmental and Distance-Based Consideration

Abstract

Butterflies possess attributes that are sensitive to gradual environmental changes. Recently, the effects of environmental factors on the shapes of organisms, as well as the interactions of these elements, have been extensively examined, i.e., effects of seasonal changes on the colors of butterfly wings, and effects of landscape structure on butterfly distribution and morphology. However, few studies have dealt with variations in butterfly shapes in response to varying environmental conditions. Here we aimed to determine how body size and shape variations in butterflies are correlated to environmental heterogeneity. We used geometric morphometrics to quantify Pieris rapae wing shape variations. Results showed that forewing and hind wing sizes were significantly different among the 15 populations. P. rapae individuals with larger wing sizes were mainly distributed in mountainous areas, whereas those with smaller-sized wings were found on the plains. Canonical variate analysis was employed to examine the patterns of variation in wing shapes among and within the populations. Significant differences in shape were revealed in the forewings and the hind wings of P. rapae populations. All populations were divided into 2 groups on the first canonical variate axis (CV1), which followed the Qinling Mountains as an important boundary between the Palearctic and Oriental Realms in zoogeographical division of the world. The unweighted pair group method with arithmetic mean (UPGMA) clustered the 15 populations into 4 groups by forewing and hind wing shape in response to the 4 environment types in Qinling Mountains. We suggest that wing shapes of P.rapae are sensitive to environmental heterogeneity. The isolating effect of the Qinling Mountains on P. rapae population interactions was apparent.