The evolutionary ecology of bird and reptile photoreceptor spectral sensitivities. (December 2019)

• Record Type: Journal Article
• Authors: Osorio, Daniel
• Is Part Of: Current opinion in behavioral sciences. Volume 30(2019)
• Page Start: 223
• Page End: 227
• Publication Date: 2019-12
• Subjects: Psychology -- Periodicals; 150.5
• DOI: 10.1016/j.cobeha.2019.10.009
• Languages: English
• ISSNs: 2352-1546

Abstract

Highlights: Birds and reptiles typically have four types of cone pigment. Spectral tuning of cones should be adapted animals' lifestyle. For diurnal birds and reptiles extensive studies reveal limited adaptive variation. Color vision is little affected by specific behavioural needs. Abstract : Birds and reptiles typically have five spectral types of visual pigment: the rod pigment, plus four cone pigments, which probably gives them tetrachromatic color vision. This system, which was inherited from ancestral vertebrates, can vary under natural selection. Most obvious is the loss of visual pigments in nocturnal lineages including mammals. This review focuses on lineages that retain the 'tetrachromatic' retina. Here, photoreceptor spectral sensitivities and the relative numbers of different photoreceptor types can vary, as can the pigmented oil droplets that narrow cone spectral sensitivities to enhance color discrimination at the expense of absolute sensitivity. One can ask how color vision evolves to suit an animal's ecology and behaviour. A key question is whether variation is attributable to the overall illumination intensity, the spectral composition of the illumination or to the reflectance spectra of objects of interest, such as the colorful communication signals of fruit, flowers and other animals. Overall the picture is of limited variation, which suggests that a common retinal bauplan is well adapted for color vision of diurnal vertebrates in terrestrial environments, while the selection due species-specific uses of color is comparatively weak.