Genetic similarity within and among populations of the Variable and Azure damelflies (Coenagrion pulchellum and C. puella)

In the first half of this century, seven species of the damselfly genus Coenagrion regularly bred in Britain. Since that time, two of these species have become extinct, and three currently have highly restricted distributions. Of the remaining two species, the Azure Damselfly (C. puella) is both common and abundant, but the Variable Damselfly (C. pulchellum), while more common than most Coenagrion species, is experiencing a national decline in Britain. The reasons for the decline of C. pulchellum are poorly understood, and therefore its future in Britain is difficult to predict. The aim of this study was to investigate genetic relationships among populations of C. puella and C. pulchellum. We obtained mitochondrial sequence data from 36 C. puella and C. pulchellum individuals collected from five different sites across central England. These revealed three haplotypes with high overall similarity. Hybridisation between C. puella and C. pulchellum was suggested by (1) The sharing of a haplotype between C. puella and C. pulchellum, and (2) The fact that morphological characters of sympatric C. puella and C. pulchellum populations are not always species-specific. More research is required before we can determine whether or not hybridisation is playing a role in the decline of Coenagrion species in the U.K.