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Absorbance of retinal oil droplets of the budgerigar : sex, spatial and plumage morph-related variation

journal contribution
posted on 2012-01-01, 00:00 authored by Ben KnottBen Knott, J Bowmaker, Mathew BergMathew Berg, Andy BennettAndy Bennett
Intraspecific variation in photoreceptor physiology is known in several vertebrate taxa, but is currently unknown in birds, despite many avian traits varying intraspecifically, and avian visual ecology encompassing a wide range of environments and visual stimuli, which might influence spectral sensitivity. Avian retinal photoreceptors contain light absorbing carotenoid-rich oil droplets that affect vision. Carotenoids are also important plumage components. However, our understanding of the regulation of carotenoids in oil droplets remains rudimentary. Among birds, Melopsittacus undulatus has probably the best-studied colour vision, shows profound intraspecific variation in plumage colour, and increased plasma carotenoids during moult. We used microspectrophotometry to determine whether a relationship exists between oil droplet carotenoid concentration and plumage pigmentation, and tested for sex and spatial variation in droplet absorbance across the retina. Absorbance of one variety of P-type droplets was higher in males. No relationship was found between droplet absorbance and plumage colour. We found a spatial pattern of droplets absorbance across the retina that matched a pattern found in another parrot, and other avian species. Our work provides insights into the development and maintenance of retinal oil droplets and suggests a common mechanism and function for carotenoid deposition in the retina across bird species.

History

Journal

Journal of Comparative Physiology A: Neuroethology, Sensory, Neural, and Behavioral Physiology

Volume

198

Issue

1

Pagination

43 - 51

Publisher

Springer

Location

Berlin, Germany

ISSN

0340-7594

eISSN

1432-1351

Language

eng

Publication classification

C1 Refereed article in a scholarly journal

Copyright notice

2012, Springer