Monitoring spatiotemporal patterns in the genetic diversity of a European butterfly species

•1. The importance of genetic diversity has been recognised by the Convention on Biological Diversity but attempts at monitoring or improving the genetic diversity of populations have been minimal. •2. Here, we investigate changes over time in the genetic diversity of a wild insect species, Maniola jurtina (Lepidoptera: Nymphalidae) and present a large-scale investigation into contemporary spatial genetic diversity. •3. Using microsatellite markers, we calculate multiple measures of genetic diversity and divergence for M. jurtina populations over 8 years in the UK and compare these findings with long-term abundance trends. •4. We also conduct a large-scale spatial analysis into the genetic diversity and population structuring of M. jurtina across Europe. •5. All UK populations sampled have high levels of gene flow and genetic diversity, with genetic diversity stable over time. •6. Across Europe, we find some population structuring between populations in the UK and the European mainland, suggesting restricted geneflow between the two regions. •7. The monitoring of a wild species' genetic diversity is an achievable aim, and one that could be carried out for many species, particularly Lepidoptera. Future approaches may aim to develop higher resolution genetic markers and cover a wider range of species. •8. The use of abundance data offers additional insight, and we find that concurrent, dedicated genetic monitoring can provide effective tracking of biodiversity trends.