WING SHAPE VARIATION IN ORTHETRUM DRAGONFLIES: FUNCTIONAL INSIGHTS FROM CITIZEN-SCIENCE IMAGES. A GEOMETRIC MORPHOMETRIC PERSPECTIVE LINKING SHAPE VARIATION AND SPECIES IDENTITY

Abstract

Wing morphology in dragonflies reflects a complex interplay of functional constraints, ecological adaptation, and sexual dimorphism. Using landmark-based geometric morphometrics on fore- and hindwings of multiple Orthetrum species, we quantified interspecific and intraspecific variation, assessed sexual shape differences, and evaluated the contribution of allometry to observed patterns. Hindwing morphology consistently captured stronger and more structured interspecific signals than forewings, with variation concentrated in functionally relevant regions such as the wing base and anal lobe. Sexual dimorphism was detectable but weaker, primarily expressed in hindwings, while forewing shape appeared constrained by stabilizing functional requirements. Allometric effects modulated but did not hide species-specific shape divergence. Notably, high-quality digital images sourced from iNaturalist have proven suitable for large-scale morphometric analyses, enabling broad geographic and taxonomic coverage. Our results highlight the potential of hindwing morphology as a tool for species discrimination and provide a framework for integrating ecological, behavioral, and genetic data to understand the drivers of wing shape evolution in Odonata.