Edge‐Rich Landscapes Promote Genetic Diversity While Arable Land Restricts It: Landscape‐Genomic Patterns Across Three Insect Species in an Agriculture‐Dominated Grassland Mosaic

ABSTRACT

Habitat loss and agricultural intensification are major drivers of insect decline, yet their consequences for intraspecific genetic diversity remain poorly understood. Here, we used landscape genomics to compare genome‐wide diversity, population differentiation and spatial patterns of gene flow in two butterfly species ( Polyommatus icarus , Melanargia galathea ) and one bush‐cricket species ( Conocephalus fuscus ) sampled across an agriculturally dominated landscape in southern Germany. The study region consists of a heterogeneous mosaic of extensively managed open grasslands maintained through conservation initiatives and embedded within intensively managed grasslands, arable fields and forest patches. High‐resolution genomic data combined with broad geographic sampling revealed pronounced interspecific differences. The highly mobile, widespread and generalist P. icarus exhibited the highest diversity and weakest population genetic structure, the moderately widespread M. galathea showed intermediate levels, whereas the comparatively less mobile orthopteran C. fuscus displayed the lowest genetic diversity and strongest population subdivision. Across the three species, genetic diversity was positively associated with edge density and showed a tendency to decline with increasing arable cover, indicating that landscape configuration influences genetic variation more strongly than habitat area alone. Effective migration surfaces showed broadly shared spatial patterns, with lower effective migration in intensively farmed areas and higher effective migration in grassland‐rich parts of the study region. Together, our results highlight that landscape heterogeneity and species‐specific ecological characteristics jointly determine genetic resilience in insects. Our findings support conserving networks of structurally diverse, well‐connected grasslands and reducing homogeneous arable matrices to help maintain genetic diversity and evolutionary potential in insect communities.