Developing and adult reef fish show rapid light‐induced plasticity in their visual system

Abstract

The visual capabilities of fish are optimized for their ecology and light environment over evolutionary time. Similarly, fish vision can adapt to regular changes in light conditions within their lifetime, e.g., ontogenetic or seasonal variation. However, we do not fully understand how vision responds to irregular short‐term changes in the light environment, e.g., algal blooms and light pollution. In this study, we investigated the effect of short‐term exposure to unnatural light conditions on opsin gene expression and retinal cell densities in juvenile and adult diurnal reef fish (convict surgeonfish; Acanthurus triostegus). Results revealed phenotypic plasticity in the retina across ontogeny, particularly during development. The most substantial differences at both molecular and cellular levels were found under constant dim light, while constant bright light and simulated artificial light at night had a lesser effect. Under dim light, juveniles and adults increased absolute expression of the cone opsin genes, sws2a, rh2c and lws, within a few days and juveniles also decreased densities of cones, inner nuclear layer cells and ganglion cells. These changes potentially enhanced vision under the altered light conditions. Thus, our study suggests that plasticity mainly comes into play when conditions are extremely different to the species' natural light environment, i.e., a diurnal fish in “constant night”. Finally, in a rescue experiment on adults, shifts in opsin expression were reverted within 24 h. Overall, our study showed rapid, reversible light‐induced changes in the retina of A. triostegus, demonstrating phenotypic plasticity in the visual system of a reef fish throughout life.

Colour pattern has no influence on the visual recognition of conspecifics by coral reef fish juveniles

“…Indeed, when faced with a choice between the butterflyfish and the convict surgeonfish, juveniles preferred conspecifics whereas when faced with two different patterns of surgeonfish, they did not elicit any significant preference. However, as the butterflyfish model happens to be the brighter and A. triostegus juveniles have a developed visual system (Fogg et al 2022), we cannot exclude the possibility this same-size species is more aversive for the juveniles than the conspecifics are attractive. Nevertheless, A. triostegus juveniles might have evolved to recognise all adult conspecifics, even those with altered colour patterns, such as an inversion of colours following stressful events (Besson 2017).…”

“…In this work, the study model was the convict surgeonfish A. triostegus, a group-living fish that typically has a white, yellowish body with black vertical stripes. This diurnal fish possesses a developed visual colour system (Fogg et al 2022). Although to our knowledge no studies have investigated visual acuity in A. triostegus, we can estimate it by comparing it with other convict fish species.…”

Genetic Variants Underlying Plasticity in Natural Populations of Spadefoot Toads: Environmental Assessment versus Phenotypic Response

“…First, the organism must assess a cue from the environment [20]. This cue may take many forms, including chemical compounds secreted by a predator, prey item, mate, or competitor [31,32]; mechanical interactions with something in the environment, such as the chewing of food [33] or direct contact between individuals [34]; molecules absorbed during digestion [35]; visual cues, such as coloration or light [36][37][38]; and climatic factors, such as temperature [39,40] and rainfall [41]. Indeed, an organism may use more than one of these cues to assess the environment [42][43][44].…”

Differential Regulation of Opsin Gene Expression in Response to Internal and External Stimuli

“…The photic conditions experienced by individuals during development are also known to influence the developmental trajectories of opsin gene expression in many fish species ( Fuller et al 2010 ; Hofmann et al 2010 ; Härer et al 2017 ; Wilwert et al 2022 ; Fogg et al 2023 ). In these species, fish reared in light environments enriched in long wavelength, characteristic of stained ( Fuller et al 2010 ) or turbid waters ( Escobar-Camacho et al 2017 ; Torres-Dowdall et al 2017 ), show accelerated developmental progression resulting in juveniles expressing an opsin gene set characteristic of adult fish ( Fuller et al 2010 ; Härer et al 2017 ).…”