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Lens and cornea limit UV vision of birds – a phylogenetic perspective

Olsson, Peter LU ; Lind, Olle LU ; Mitkus, Mindaugas LU ; Delhey, Kaspar and Kelber, Almut LU (2021) In Journal of Experimental Biology 224(20).
Abstract

Most vertebrates have UV-sensitive vision, but the UV sensitivity of their eyes is limited by the transmittance of the ocular media, and the specific contribution of the different media (cornea, lens) has remained unclear. Here, we describe the transmittance of all ocular media (OMT), as well as that of lenses and corneas of birds. For 66 species belonging to 18 orders, the wavelength at which 50% of light is transmitted through the ocular media to the retina (λT0.5) ranges from 310 to 398 nm. Low λT0.5 corresponds to more UV light transmitted. Corneal λT0.5 varies only between 300 and 345 nm, whereas lens λT0.5 values are more variable (between 315 and 400 nm) and tend to be the limiting... (More)

Most vertebrates have UV-sensitive vision, but the UV sensitivity of their eyes is limited by the transmittance of the ocular media, and the specific contribution of the different media (cornea, lens) has remained unclear. Here, we describe the transmittance of all ocular media (OMT), as well as that of lenses and corneas of birds. For 66 species belonging to 18 orders, the wavelength at which 50% of light is transmitted through the ocular media to the retina (λT0.5) ranges from 310 to 398 nm. Low λT0.5 corresponds to more UV light transmitted. Corneal λT0.5 varies only between 300 and 345 nm, whereas lens λT0.5 values are more variable (between 315 and 400 nm) and tend to be the limiting factor, determining OMT in the majority of species. OMT λT0.5 is positively correlated with eye size, but λT0.5 of corneas and lenses are not correlated with their thickness when controlled for phylogeny. Corneal and lens transmittances do not differ between birds with UV- and violet-sensitive SWS1 opsin when controlling for eye size and phylogeny. Phylogenetic relatedness is a strong predictor of OMT, and ancestral state reconstructions suggest that from ancestral intermediate OMT, highly UV-transparent ocular media (low λT0.5) evolved at least five times in our sample of birds. Some birds have evolved in the opposite direction towards a more UV-opaque lens, possibly owing to pigmentation, likely to mitigate UV damage or reduce chromatic aberration.

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author
; ; ; and
organization
publishing date
type
Contribution to journal
publication status
published
subject
keywords
Bird visual ecology, Colour vision, Spectral sensitivity, Ultraviolet vision
in
Journal of Experimental Biology
volume
224
issue
20
article number
jeb243129
publisher
The Company of Biologists Ltd
external identifiers
  • scopus:85119492834
  • pmid:34581400
ISSN
0022-0949
DOI
10.1242/jeb.243129
language
English
LU publication?
yes
additional info
Funding Information: The study was financially supported by The Swedish Research Council, Stockholm (2012?2212 and 2016-03298). M.M. was supported in part by a fellowship from the Marius Jakulis Jason Foundation, Lithuania. Open Access funding provided by Lunds Universitet. Deposited in PMC for immediate release. Funding Information: The study was financially supported by The Swedish Research Council, Stockholm (2012–2212 and 2016-03298). M.M. was supported in part by a fellowship from the Marius Jakulis Jason Foundation, Lithuania. Open Access funding provided by Lunds Universitet. Deposited in PMC for immediate release. Publisher Copyright: © 2021. Published by The Company of Biologists Ltd
id
0fdd6a8f-d5dc-4bf8-8abd-a3403a8b5df6
date added to LUP
2021-12-20 16:48:01
date last changed
2024-06-15 23:01:05
@article{0fdd6a8f-d5dc-4bf8-8abd-a3403a8b5df6,
  abstract     = {{<p>Most vertebrates have UV-sensitive vision, but the UV sensitivity of their eyes is limited by the transmittance of the ocular media, and the specific contribution of the different media (cornea, lens) has remained unclear. Here, we describe the transmittance of all ocular media (OMT), as well as that of lenses and corneas of birds. For 66 species belonging to 18 orders, the wavelength at which 50% of light is transmitted through the ocular media to the retina (λ<sub>T0.5</sub>) ranges from 310 to 398 nm. Low λ<sub>T0.5</sub> corresponds to more UV light transmitted. Corneal λ<sub>T0.5</sub> varies only between 300 and 345 nm, whereas lens λ<sub>T0.5</sub> values are more variable (between 315 and 400 nm) and tend to be the limiting factor, determining OMT in the majority of species. OMT λ<sub>T0.5</sub> is positively correlated with eye size, but λ<sub>T0.5</sub> of corneas and lenses are not correlated with their thickness when controlled for phylogeny. Corneal and lens transmittances do not differ between birds with UV- and violet-sensitive SWS1 opsin when controlling for eye size and phylogeny. Phylogenetic relatedness is a strong predictor of OMT, and ancestral state reconstructions suggest that from ancestral intermediate OMT, highly UV-transparent ocular media (low λ<sub>T0.5</sub>) evolved at least five times in our sample of birds. Some birds have evolved in the opposite direction towards a more UV-opaque lens, possibly owing to pigmentation, likely to mitigate UV damage or reduce chromatic aberration.</p>}},
  author       = {{Olsson, Peter and Lind, Olle and Mitkus, Mindaugas and Delhey, Kaspar and Kelber, Almut}},
  issn         = {{0022-0949}},
  keywords     = {{Bird visual ecology; Colour vision; Spectral sensitivity; Ultraviolet vision}},
  language     = {{eng}},
  number       = {{20}},
  publisher    = {{The Company of Biologists Ltd}},
  series       = {{Journal of Experimental Biology}},
  title        = {{Lens and cornea limit UV vision of birds – a phylogenetic perspective}},
  url          = {{http://dx.doi.org/10.1242/jeb.243129}},
  doi          = {{10.1242/jeb.243129}},
  volume       = {{224}},
  year         = {{2021}},
}