Habitat‐related variation in the plasticity of a UV‐sensitive photoreceptor over a small spatial scale in the palmate newt

Abstract

Plastic phenotypes are expected to be favoured in heterogeneous environments compared with stable environments. Sensory systems are interesting to test this theory because they are costly to produce and support, and strong fitness costs are expected if they are not tuned to the local environment. Consistently, the visual system of several species changes with the conditions experienced during early development. However, there is little information on whether the amplitude of the change, that is the reaction norm, differs between visual environments. Given the rapid change of many ecosystems, especially eutrophication for aquatic habitats, it is crucial to determine down to which spatial scale, change in the reaction norm occurs. We addressed this issue by quantifying the between-habitat variation in the expression of a UV-sensitive opsin in a newt. In western France, this species breeds in ponds of small forest patches, where water filters out UV, and in agricultural ponds where UV transmission is variable. We raised larvae from both habitats with or without exposure to UV. Opsin expression was reduced in larvae from agricultural habitats when raised without UV, whereas it was low in larvae from forest ponds under all lighting conditions. Thus, the variation in the reaction norm of opsin expression was lower in stable filtering environments and higher in heterogeneous environments. Its variation occurred between habitats across a small spatial scale. We discuss the hypotheses for this pattern and for the maintenance of residual opsin expression in forest populations.

Ecology drives patterns of spectral transmission in the ocular lenses of frogs and salamanders

“…There is limited behavioural (Dietz, 1972; Han et al., 2007; Kats et al, 2012; Przyrembel et al., 1995; Secondi et al., 2012) and electrophysiological (Deutschlander & Phillips, 1995; Govardovskii & Zueva, 1974; La Touche & Kimeldorf, 1979; Martin et al., 2016; Perry & McNaughton, 1991) evidence thus far that some amphibians are also sensitive in this part of the spectrum. Representatives of all classes of vertebrate (Bowmaker, 2008), including amphibians (Korenyak & Govardovskii, 2013; Ma et al., 2001; Martin et al., 2016; Mège et al., 2016; Secondi et al., 2017), have visual pigments with maximum sensitivity ( λ max ) in the UV, although among amphibians, only salamanders have been demonstrated to have cones with a UV λ max , whereas the shortest wavelength cones identified in frogs all have maximum sensitivity in the violet (Donner & Yovanovich, 2020).…”

Adult plasticity in African cichlids: Rapid changes in opsin expression in response to environmental light differences

“…One other molecular mechanism for altering spectral sensitivity that can be both genetically determined and environmentally induced, thereby having the potential to act across varied time scales, is changes in opsin gene expression (Secondi et al 2017; Macias-Munoz et al 2015; Carleton et al 2010; Carleton et al 2008; Fuller et al 2005). Across species, opsin expression variation in African cichlids causes significant differences in spectral sensitivities between closely related taxa (Carleton 2009; Parry et al 2005).…”

“…One other molecular mechanism for altering spectral sensitivity that can be both genetically determined and environmentally induced, thereby having the potential to act across varied time scales, is changes in opsin gene expression (Carleton et al, 2008(Carleton et al, , 2010Fuller, Carleton, Fadool, Spady, & Travis, 2005;Macias-Munoz, Smith, Monteiro, & Briscoe, 2015;Secondi et al, 2017).…”

Linkages between stratospheric ozone, UV radiation and climate change and their implications for terrestrial ecosystems

“…This suggests that changes in the amount of UV radiation in the environment during the development of these newts could affect visual sensitivity in the UV region. 197,198 The role of UV-B radiation has been relatively well-studied in the case of lizards. Lizards kept in captivity are routinely exposed to low background levels of UV-B radiation to enhance vitamin D synthesis and their overall health.…”