The Glanville fritillary butterfly inhabits fragmented landscapes in the Åland Islands, Finland, where the long-term persistence of this classic metapopulation depends on frequent re-colonisation events. A number of studies have focused on understanding how dispersal propensity varies within this system, what the underlying mechanisms are, and how variation in dispersal influences metapopulation dynamics. In the mid-2000s the focus turned to a potential candidate gene, phosphoglucose isomerase (Pgi) that was soon found to have effects on phenotypic performance of individuals in regard to their dispersal potential but also other key life-history traits. Variation in Pgi has further been shown to affect population dynamics. Here we review 30 research papers in which associations of Pgi polymorphism with metabolic rate, mobility, fecundity, lifespan, and population growth rate in the Glanville fritillary are discussed. The studies highlight the role of environmental variation and landscape structure in maintaining genetic polymorphism in this study system.