Abstract
Exposed and isolated alpine ecosystems present evolutionary challenges for flying species worldwide. Many insects have undergone dramatic wing reduction in response to these harsh conditions, losing the ability to fly. By contrast, some taxa have countered alpine conditions by evolving larger wings to improve flight ability. In this study, we investigated how two independent clades of Zelandoperla fenestrata stoneflies respond to upland environments. Our results revealed strikingly different adaptations to elevation across the two closely related clades. In Clade 1 (southern South Island), wing length decreases sharply with increasing elevation. In contrast, wing length in the geographically adjacent Clade 2 (northern South Island, and North Island) increases with elevation. These contrasting strategies highlight the diverse adaptive pathways that may exist even for closely related lineages encountering similar environmental challenges.