Variation in morphology between core and marginal populations of three British damselflies

As selective pressures are altered by the changing climate, species have been shown to shift their distributions. Here we investigate morphological variation in dispersal-related traits between core and marginal populations in three species of Odonata, a taxon that is known to be expanding polewards. We sampled individuals of (i) Calopteryx splendens, a species with a rapidly expanding range, (ii) Erythromma najas, a species with a slowly expanding range, and (iii) Pyrrhosoma nymphula, a species that does not exhibit a range margin in the UK (as a control). Only C. splendens exhibited consistent trends within two dispersal-related traits (wing: abdomen length ratio and aspect ratio). This result suggests that proximity to range margin alone does not account for variations in damselfly morphology, but that the rate of range expansion may also be important in determining variation.