Phenotypic plasticity of UV vision in newts
Vision is a key sense involved in social interactions, foraging and predator avoidance. Visual capacities of organisms are expected to be tuned to their sensory environment. However, lighting conditions often vary across space and time. It is thus crucial to determine whether visual capacities are environment-dependent or fixed, and whether behavioural performances depend on lighting conditions. Most amphibians breed and develop in water bodies where UV transmission drastically differs between and within habitats. Maintaining functional UV vision may enhance biological functions like communication or foraging when UV wavelengths are present but may be costly when they are unavailable. This physiological trade-off may be solved by expressing UV opsins only in UV-rich environments. We investigated the plasticity of UV vision in the newt Lissotriton vulgaris. Larvae were exposed to or deprived of UV lighting during development. We measured opsin expression and staged foraging tests in UV+ and UV- lighting conditions. Foraging performance was reduced in UV deprived larvae and in UV- lighting. The expression of SWS1 (UV sensitive) opsin was also decreased by half whereas the expression of LWS opsin (yellow-red sensitive) remained constant. Opsin expression is therefore reduced and not suppressed in environments lacking UV. We additionally tested the effect of parental and larval environment to assess the relative contribution of genetics and plasticity to opsin expression. Finally, we found functional sequences of SWS1 opsins from most Caudata families which suggest that UV vision is widespread in amphibians. We discuss the implications of plastic visual capacities in this group.
Martin M., Secondi J., Mège P., Rodgers G. and Théry M. (2014) Phenotypic plasticity of UV vision in newts. The 15th conference of the International Society of Behavioral Ecology. New York City, USA. Talk