Seasonal phenotypic variation in the speckled wood butterfly (Pararge aegeria L.): Patterns in and relationships between wing characters

We studied the variation in dorsal wing colour, dorsal hindwing spotting and wing length within a population of the speckled wood butterfly Pararge aegeria (L.) in two successive years. Over time in the first generation, successively emerging butterflies were darker, larger and of higher spot type (a clearer fourth submarginal spot). In the second generation they remained on average rather dark and of median size, but variation in spotting repeated the pattern of the first generation. We interpret these patterns of variation in colour and size in relation to seasonal changes in the irradiance conditions within a temperate forest. We suggest that there is a larger genetic control of spotting than of wing colour and wing length. Females were darker, larger and of higher spot type than males. Darker males were on average larger and of higher spot type than pale males. These relationships can be interpreted in relation to the males' mate-locating strategies.