Ultraviolet radiation exposure during larval development is associated with changes in colouration of Green and Golden Bell Frogs (Ranoidea aurea).

Ultraviolet (UV) radiation can be harmful to amphibians by causing DNA damage, impairing immune systems and restricting growth. In response to elevated UV, amphibians have been observed to invest in skin darkening for photoprotection. However, it is unclear whether investment in pigmentation persists across life stages, or whether there are other carry-over effects of UV exposure on amphibian colouration. Here, we experimentally investigate the effects of larval UV exposure on larval and post-metamorphic colouration of the threatened Green and Golden Bell Frog (Ranoidea aurea). UV exposure was provided via two treatments: low UV (∼0.3 - 0.9 UVI) and high UV (∼0.8 - 2.6 UVI), both within the intensity range in nature. Over the experimental period, colouration was measured at weeks 4, 6, and 8, and then immediately post-metamorphosis. As expected, larvae reared under higher UV exhibited stronger skin darkening up until metamorphosis. This trend persisted post-metamorphosis, with metamorphs from the high UV treatment exhibiting darker colouration. Metamorphs from the high UV treatment also displayed a higher proportion of gold colouration that was long-wave shifted in hue and lower in chroma. Collectively, these findings provide some of the first evidence that UV exposure has carry-over effects on amphibian colouration.