Spatial and temporal variation in flight morphology in the butterfly Melitaea cinxia (Lepidoptera: Nymphalidae)

Some studies on insects have found a relationship between habitat structure and investment in dispersal-related traits. In this study we compared the morphology of the butterfly Melitaea cinxia from five sites on the large Baltic island Öland that differed markedly in degree of fragmentation and size. Both wild-caught adults and individuals reared in a split-plot design were compared. We found significant site differences in size-adjusted thorax mass and total body mass. Male thorax mass was on average larger among the sites with the highest degree of habitat fragmentation. However, due to significant sex–site interactions, males and females may have adapted differently to the habitat fragmentation. Using museum specimens, we also analysed changes in morphology, finding an increase in size (measured as head and thorax width) over time. Thorax width appears to have increased among females and decreased among males. Possible explanations include increasing fragmentation of the landscape and changes in population density.  © 2002 The Linnean Society of London, Biological Journal of the Linnean Society , 2002, 77 , 445–453.