UV sensitive vision in cardinals and tanagers is ubiquitous

ABSTRACT

Short wavelength visual sensitivity in birds is determined mostly by the type of photopigment present in the short-wavelength sensitive cone 1 (SWS1) which varies between clades and takes two main forms: the violet sensitive type (VS) and ultraviolet sensitive type (UVS). The common ancestor of passerines is thought to have been UVS, but there were at least 8 transitions between both types of visual sensitivity, even within species of the same family (Maluridae). The type of visual system a species has is a key parameter of avian visual models employed to describe chromatic visual perception and assess if colour differences are discernible by birds. Cardinalidae and Thraupidae together include more than 400 very diverse species that were model organisms in many bird colouration studies. However, visual sensitivity has been characterised for only one species of each of these families so far. Here, we obtained partial genetic sequences of the SWS1 opsin gene that determines the spectral sensitivity of the photopigment for a phylogenetically broad species sample of these families. All cardinals and tanagers studied here have SWS1 sequences corresponding with UVS sensitivity, suggesting that this character is conserved in these bird families despite their highly diverse range of plumage colours and habitat types.

KEYWORDS:

• SWS1
• colour vision
• UV
• Cardinalidae
• Thraupidae

Acknowledgements

We would like to acknowledge two anonymous reviewers for their insightful comments on a previous version of this manuscript, which contributed to improving it. We also thank Cecilia Kopuchian for her help on setting up the lab work.

Disclosure statement

No potential conflict of interest was reported by the authors.

Supplementary material

Supplemental data for this article can be accessed here.

Additional information

Funding

This work was supported by the Agencia Nacional de Promoción Científica y Tecnológica; under Grant PICT-2015-3560 and by CONICET under Grant PUE 2016-098.