Seasonal cycle in vitamin A1/A2-based visual pigment composition during the life history of coho salmon (Oncorhynchus kisutch)

SUMMARYSignal reception and production form the basis of animal visual communication, and are largely constrained by environmental light. However, the role of environmental light in producing variation in either signal reception or production has not been fully investigated. To chart the effect of environmental light on visual sensitivity and body colouration throughout ontogeny, we measured spectral sensitivity, lens transmission and body pattern reflectance from juvenile and adult Nile tilapia held under two environmental light treatments. Spectral sensitivity in juveniles reared under a broad-spectrum light treatment and a red-shifted light treatment differed mostly at short wavelengths, where the irradiance of the two light treatments differed the most. In contrast, adults held under the same two light treatments did not differ in spectral sensitivity. Lens transmission in both juveniles and adults did not differ significantly between environmental light treatments, indicating that differences in spectral sensitivity of juveniles originated in the retina. Juveniles and adults held under the two environmental light treatments differed in spectral reflectance, and adults transferred to a third, white light treatment differed in spectral reflectance from their counterparts held under the two original treatments. These results demonstrate that environmental light plays a crucial role in shaping signal reception in juveniles and signal production throughout ontogeny, reinforcing the notion that environmental light has the capacity to influence animal communication, and suggesting that the characteristics of environmental light should be considered in models of ecological speciation.Key words: ontogenetic variation, visual sensitivity, body colouration, sensory drive, animal communication. (Kocher, 2004), and are a growing presence in laboratory research (El-Sayed, 2006). Cichlid fish show variation in signal reception, as visual pigment complements show a great range of natural variation (Carleton and Kocher, 2001;Parry et al., 2005;Sabbah et al., 2010;O'Quin et al., 2010). Additionally, cichlids are notorious for their variation in signal production, showing myriad behaviours (Barlow, 2000) and body colourations (Kornfield and Smith, 2000), many of which are species specific (Hofmann et al., 2009). When these sources of variation are coupled with changes in the spectral quality of available environmental light, which, for example, occur as water depth varies (e.g. Sabbah et al., 2011), the basic requirements for sensory drive are met. However, the role of environmental light in these sources of variation, particularly signal production, remains somewhat elusive.Nile tilapia have been shown to differentially express seven visual pigments throughout ontogeny: SWS1 (360nm), SWS2b (425nm), SWS2a (456nm), Rh2b (472nm), Rh2aβ (518nm), Rh2aα (528nm) and LWS (561nm) (Spady et al., 2006). Juveniles predominantly express SWS2b, SWS2a, Rh2a (a combination of Rh2aβ and Rh2aα, as their maximum absorbance wavelengt...

Section: Effect Of Environmental Light On Signal Reception Throughoutsupporting

confidence: 56%

Modulation of environmental light alters reception and production of visual signals in Nile tilapia

Hornsby

Sabbah

Robertson

et al. 2013

“…Alternative reasons for an A 1 -A 2 shift in visual pigments has been examined in several species such as salamanders, bullfrogs, carp, salmonids and the Japanese dace (Ala-Laurila et al, 2004Ueno et al, 2005;Temple et al, 2006). These studies revealed a correlation between day length, temperature and migration to different photic conditions as driving factors for shifting from an A 1 to an A 2 pigment, while acknowledging that other external factors may be present.…”

Section: Spectral Sensitivity Of Retinal Photoreceptorsmentioning

confidence: 99%

Spatial resolving power and spectral sensitivity of the saltwater crocodile, Crocodylus porosus, and the freshwater crocodile, Crocodylus johnstoni

Nagloo

Collin

Hemmi

et al. 2016

Crocodilians are apex amphibious predators that occupy a range of tropical habitats. In this study, we examined whether their semiaquatic lifestyle and ambush hunting mode are reflected in specific adaptations in the peripheral visual system. Design-based stereology and microspectrophotometry were used to assess spatial resolving power and spectral sensitivity of saltwater (Crocodylus porosus) and freshwater crocodiles (Crocodylus johnstoni). Both species possess a foveal streak that spans the naso-temporal axis and mediates high spatial acuity across the central visual field. The saltwater crocodile and freshwater crocodile have a peak spatial resolving power of 8.8 and 8.0 cycles deg, respectively. Measurement of the outer segment dimensions and spectral absorbance revealed five distinct photoreceptor types consisting of three single cones, one twin cone and a rod. The three single cones (saltwater/freshwater crocodile) are violet (424/426 nm λ max ), green (502/510 nm λ max ) and red (546/ 554 nm λ max ) sensitive, indicating the potential for trichromatic colour vision. The visual pigments of both members of the twin cones have the same λ max as the red-sensitive single cone and the rod has a λ max at 503/510 nm (saltwater/freshwater). The λ max values of all types of visual pigment occur at longer wavelengths in the freshwater crocodile compared with the saltwater crocodile. Given that there is a greater abundance of long wavelength light in freshwater compared with a saltwater environment, the photoreceptors would be more effective at detecting light in their respective habitats. This suggests that the visual systems of both species are adapted to the photic conditions of their respective ecological niche.

“…The capacity for Stickleback visual pigments chromophore-based tuning is genetically determined (requiring conversion of A1 into A2 by a retinol dehydrogenase), but when present, it allows tuning pigments on a physiological time scale, e.g. seasonally (Beatty, 1975;Temple et al, 2006) or for different stages of life history (Wald, 1946;Carlisle and Denton, 1959;Reuter, 1969;Reuter et al, 1971). The A1 to A2 switch red-shifts and broadens the absorption spectrum (Dartnall and Lythgoe, 1965;Whitmore and Bowmaker, 1989;Hárosi, 1994;Parry and Bowmaker, 2000; see also Bridges, 1972) by lowering the energy barrier for activation, and is always associated with a decrease in thermal stability of the pigment (Ala-Laurila et al, 2004a;Ala-Laurila et al, 2004b;Ala-Laurila et al, 2007;Luo et al, 2008;Luo et al, 2011).…”

Section: Introductionmentioning

confidence: 99%

Spectral tuning by selective chromophore uptake in rods and cones of eight populations of nine-spined stickleback (Pungitius pungitius)

Saarinen

Pahlberg

Herczeg

et al. 2012

SUMMARYThe visual pigments of rods and cones were studied in eight Fennoscandian populations of nine-spined stickleback (Pungitius pungitius). The wavelength of maximum absorbance of the rod pigment ( max ) varied between populations from 504 to 530nm. Gene sequencing showed that the rod opsins of all populations were identical in amino acid composition, implying that the differences were due to varying proportions of chromophores A1 and A2. Four spectral classes of cones were found (two Scones, M-cones and L-cones), correlating with the four classes of vertebrate cone pigments. For quantitative estimation of chromophore proportions, we considered mainly rods and M-cones. In four populations, spectra of both photoreceptor types indicated A2 dominance (population mean  max 525-530nm for rods and 535-544nm for M-cones). In the four remaining populations, however, rod spectra (mean  max 504-511nm) indicated strong A1 dominance, whereas M-cone spectra (mean  max 519-534nm) suggested substantial fractions of A2. Quantitative analysis of spectra by three methods confirmed that rods and cones in these populations use significantly different chromophore proportions. The outcome is a shift of M-cone spectra towards longer wavelengths and a better match to the photic environment (light spectra peaking >560nm in all the habitats) than would result from the chromophore proportions of the rods. Chromophore content was also observed to vary partly independently in M-and L-cones with potential consequences for colour discrimination. This is the first demonstration that selective processing of chromophore in rods and cones, and in different cone types, may be ecologically relevant. Supplementary material available online at