Abstract The evolution of shortwave vision in frogs and toads (anurans) has remained unclear, because molecular and behavioural evidence suggest a contrasting picture regarding their UV sensitivity. Although all anurans studied to date express violet-peaking SWS1 pigments, many species possess UV-transmissive lenses and show behaviours consistent with UV detection, raising questions about how SWS1 spectral tuning has evolved. Here, we combined sequence analyses with functional characterization o