Data from: Behavioural red-light sensitivity in fish according to the optomotor response

Various procedures have been adopted to investigate spectral sensitivity of animals, e.g., absorption spectra of visual pigments, electroretinography, optokinetic response, optomotor response (OMR), and phototaxis. These works have led to various conclusions about animal vision. However, visual sensitivity should be evaluated consistently for a reliable comparison. In this study, we retrieved behavioural data of several fish species that used a unified procedure for the OMR test and compared the sensitivities to near-infrared light. Besides cavefish that lack eyes, some species were not appropriate for the OMR test because they either stayed still or changed swimming direction frequently. Eight fish species out of 13 species tested were OMR positive. Detailed analyses using goldfish, zebrafish, guppy, medaka, stickleback, and cichlid revealed that all the fish were sensitive to light at λ ≥ 750 nm, where the threshold wavelengths varied from 750 nm to 880 nm. Fish opsin repertoire enabled the perception of red light. In contrast, the copy number of long-wave-sensitive (LWS) genes did not necessarily improve red-light sensitivity. The duplication of LWS and other cone opsin genes that have occurred extensively during fish evolution might not aid increasing spectral sensitivity, but provide some other ophthalmic function, such as enhanced spectral discrimination.

学界已采用多种实验范式探究动物的光谱敏感度，例如视色素吸收光谱检测、视网膜电图、视动眼反应、运动视动反应（optomotor response, OMR）以及趋光性实验。此类研究已积累了诸多有关动物视觉的结论。然而，若要开展可靠的跨物种比较，需采用统一标准评估视觉敏感度。本研究检索了采用统一运动视动反应（OMR）实验范式的多种鱼类行为学数据，并对比了它们对近红外光的敏感度。除无眼洞穴鱼外，部分鱼类因持续静止或频繁改变游泳方向，不适用于OMR实验范式。在13种受试鱼类中，有8种呈现OMR阳性反应。针对金鱼、斑马鱼、孔雀鱼、青鳉、棘鱼以及慈鲷的详细分析显示，所有受试鱼类均对波长≥750nm的光线敏感，其敏感阈值波长区间为750nm至880nm。鱼类视蛋白组的多样性赋予了其红光感知能力。与之相反，长波敏感（long-wave-sensitive, LWS）基因的拷贝数未必能提升红光敏感度。在鱼类演化过程中广泛发生的LWS基因与其他视锥视蛋白基因复制事件，或许并未提升光谱敏感度，而是赋予了其他视觉功能，例如增强光谱分辨能力。