Convergent evolution of failure- and wear-prevention in radulae of rock-scraping land snails (Chondrinidae, Gastropoda)

Abstract This study investigates the morphology, material and mechanical properties of radular teeth in six lineages of Chondrinidae, a family of terrestrial gastropods. We examined three species that forage on biofilms from mixed substrates (Abida secale, Granopupa granum and Granaria frumentum) and three that specialized in scraping lichen off rock faces (Chondrina arcadica, Rupestrella rhodia and Solatopupa similis). Using scanning electron microscopy, nanoindentation and energy-dispersive X-ray spectroscopy, we analysed tooth morphology, hardness (H), Young’s modulus (E) and elemental composition. Our findings confirm that the central radular region reflects substrate preferences, with rock-scraping species exhibiting reduced tooth denticles and significantly higher E and H values compared to mixed substrate feeders. Correlations between mechanical properties and elemental composition (increased calcium or silicon content) suggest convergently evolved strengthening mechanisms in rock-scraping species. The results support hypotheses of parallel evolution in radular adaptations, highlighting Chondrinidae as a valuable model for studying the interplay of morphology, function, ecology and evolution.