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Avian retinal oil droplets : dietary manipulation of colour vision?

journal contribution
posted on 2010-03-22, 00:00 authored by Ben KnottBen Knott, Mathew BergMathew Berg, E Morgan, Kate BuchananKate Buchanan, J Bowmaker, Andy BennettAndy Bennett
Avian vision is highly developed, with bird retinas containing rod and double-cone photoreceptors, plus four classes of single cones subserving tetrachromatic colour vision. Cones contain an oil droplet, rich in carotenoid pigments (except VS/ultraviolet-sensitive cones), that acts as a filter, substantially modifying light detected by the photoreceptor. Using dietary manipulations, we tested the effects of carotenoid availability on oil droplet absorbance properties in two species: Platycercus elegans and Taeniopygia guttata. Using microspectrophotometry, we determined whether manipulations affected oil droplet carotenoid concentration and whether changes would alter colour discrimination ability. In both species, increases in carotenoid concentration were found in carotenoid-supplemented birds, but only in the double cones. Magnitudes of effects of manipulations were often dependent on retinal location. The study provides, to our knowledge, the first experimental evidence of dietary intake over a short time period affecting carotenoid concentration of retinal oil droplets. Moreover, the allocation of carotenoids to the retina by both species is such that the change potentially preserves the spectral tuning of colour vision. Our study generates new insights into retinal regulation of carotenoid concentration of oil droplets, an area about which very little is known, with implications for our understanding of trade-offs in carotenoid allocation in birds.

History

Journal

Proceedings of the Royal Society B-biological sciences

Volume

277

Issue

1683

Pagination

953 - 962

Publisher

The Royal Society

Location

London, England

ISSN

0962-8452

eISSN

1471-2954

Language

eng

Publication classification

C1 Refereed article in a scholarly journal

Copyright notice

2009, The Royal Society