Clinal Variation in the Common Brown Butterfly Heteronympha merope merope (Lepidoptera: Satyrinae)

Abstract

Analyses of variation in seven wing pattern characters in H. merope merope females, from 22 sites throughout the range of the subspecies, show that the variation generally has a substantial genetic component. All characters exhibit significant interpopulation variation and one character (S) shows an obvious clinal pattern in a north-south direction. Variation in the total wing phenotype was examined by a multivariate principal component analysis. The first two principal components identified also show a clinal pattern: a north-south cline in component 1 and an east-west cline in component 2. Variation in component 1 is significantly associated with winter humidity and that in the second with yearly rainfall. Because the components cannot be identified simply as size, shape or colour vectors the possible adaptive significance of the results is not clear, although there is some indirect evidence that the pattern of variation is due to natural selection rather than random processes.