The fragmented population structure of the Sardinian chalk hill blue butterfly (Lepidoptera, Lycaenidae)

Summary demic Sardinian chalk hill blue butterfly, Polyommatus coridon gennargenti, is considered vulnerable to extinction because of its low genetic variation and restricted distribution. The species also has a fragmented distribution, which follows the patchy distribution pattern of its larval host-plant. A preliminary investigation of the population structure of P. coridon gennargenti was carried out on a small network of four local populations by means of capture–recapture methods. Estimated population sizes and movement rates among the four adjacent local populations suggest that this taxon has a metapopulation structure composed of loosely connected small local populations. Natural fragmentation, isolation, and traditional land use contribute to the vulnerability of P. coridon gennargenti to extinction. Low effective population sizes and restricted movement between habitat patches lead to inbreeding and an increased vulnerability to extinction of this island population.