Genetic structure among and diversity within natural populations is influenced by acombination of ecological and evolutionary processes. These processes can differentlyinfluence neutral and functional genetic diversity and also vary according toenvironmental settings. To investigate the roles of interacting processes as drivers ofpopulation‐level genetic diversity in the wild, we compared neutral and functionalstructure and diversity between 20 Tetrix undulata pygmy grasshopper populations indisturbed and stable habitats. Genetic differentiation was evident among the differentpopulations, but there was no genetic separation between stable and disturbedenvironments. The incidence of long‐winged phenotypes was higher in disturbedhabitats, indicating that these populations were recently established by flight‐capablecolonizers. Color morph diversity and dispersion of outlier genetic diversity, estimatedusing AFLP markers, were higher in disturbed than in stable environments,likely reflecting that color polymorphism and variation in other functionally importanttraits increase establishment success. Neutral genetic diversity estimated usingAFLP markers was lower in disturbed habitats, indicating stronger eroding effects onneutral diversity of genetic drift associated with founding events in disturbed comparedto stable habitats. Functional diversity and neutral diversity were negativelycorrelated across populations, highlighting the utility of outlier loci in genetics studiesand reinforcing that estimates of genetic diversity based on neutral markers donot infer evolutionary potential and the ability of populations and species to copewith environmental change.