Contrasting genetic responses to habitat fragmentation for two Lycaenid butterfly species

Biodiversity is currently declining at the global scale. Apart from species declines and lowered abundances, the loss of genetic diversity is equally concerning as it may undermine fitness and the potential to adapt to future environmental change. We compared genetic diversity of historical and recent Alpine populations of two butterfly species, Lycaena helle and L. hippothoe, over a period of about 10 years. Using microsatellite markers, we found no changes over time in L. helle, while genetic diversity decreased, and differentiation increased in L. hippothoe. Lycaena helle inhabits peat bogs and wetland fallows with populations being strongly isolated, while L. hippothoe used to occur in population networks on hay meadows, with the latter being strongly exposed to agricultural intensification. We conclude that currently L. hippothoe populations are strongly declining due to changes in land use, resulting in genetic erosion potentially due to the collapse of population networks.