Diversity of mammalian photoreceptor properties: Adaptations to habitat and lifestyle?
Article first published online: 2 OCT 2005
Copyright © 2005 Wiley-Liss, Inc.
The Anatomical Record Part A: Discoveries in Molecular, Cellular, and Evolutionary Biology
Special Issue: Nature's Experiments in Brain Diversity
Volume 287A, Issue 1, pages 1001–1012, November 2005
How to Cite
Peichl, L. (2005), Diversity of mammalian photoreceptor properties: Adaptations to habitat and lifestyle?. Anat. Rec., 287A: 1001–1012. doi: 10.1002/ar.a.20262
- Issue published online: 25 OCT 2005
- Article first published online: 2 OCT 2005
- Manuscript Accepted: 17 AUG 2005
- Manuscript Received: 16 AUG 2005
- cone photoreceptors;
- rod photoreceptors;
- color vision;
All mammalian retinae contain rod photoreceptors for low-light vision and cone photoreceptors for daylight and color vision. Most nonprimate mammals have dichromatic color vision based on two cone types with spectrally different visual pigments: a short-wavelength-sensitive (S-)cone and a long-wavelength-sensitive (L-)cone. Superimposed on this basic similarity, there are remarkable differences between species. This article reviews some striking examples. The density ratio of cones to rods ranges from 1:200 in the most nocturnal to 20:1 in a few diurnal species. In some species, the proportion of the spectral cone types and their distribution across the retina deviate from the pattern found in most mammals, including a complete absence of S-cones. Depending on species, the spectral sensitivity of the L-cone pigment may peak in the green, yellow, or orange, and that of the S-cone pigment in the blue, violet, or near-ultraviolet. While exclusive expression of one pigment per cone is the rule, some species feature coexpression of the L- and S-pigment in a significant proportion of their cones. It is widely assumed that all these variations represent adaptations to specific visual needs associated with particular habitats and lifestyles. However, in many cases we have not yet identified the adaptive value of a given photoreceptor arrangement. Comparative anatomy is a fruitful approach to explore the range of possible arrangements within the blueprint of the mammalian retina and to identify species with particularly interesting or puzzling patterns that deserve further scrutiny with physiological and behavioral assays. © 2005 Wiley-Liss, Inc.