Color discrimination in the red range with only one long-wavelength sensitive opsin
Author
Summary, in English
The basic precondition for color vision is the presence of at least two receptor types with different spectral sensitivities. The sensitivity of a receptor is mostly defined by the opsin-based visual pigment expressed in it. We show here, through behavioral experiments, that the nymphalid butterfly Heliconius erato, although it expresses short and medium wavelength opsins and only one long wavelength opsin, discriminates colors in the long-wavelength range (590 nm, 620 nm and 640 nm), whereas another nymphalid, Vanessa atalanta, despite having color vision, is unable to do so. In the eyes of H. erato we identified filtering pigments very close to the rhabdom which differ between ommatidia and produce the yellow and red ommatidial reflection seen under orthodromic illumination. The eyes of V. atalanta lack the filtering pigments, and reflect a homogeneous orange. We hypothesize that the filtering pigments found in the eyes of H. erato may shift the spectral sensitivity peak of the long wavelength receptors in some ommatidia towards longer wavelengths. The comparison of the signals between the two new receptor types makes color discrimination in the red range possible. To our knowledge, this is the first behavioral proof of color vision based on receptors expressing the same opsin.
Publishing year
2006
Language
English
Pages
1944-1955
Publication/Series
Journal of Experimental Biology
Volume
209
Issue
10
Document type
Journal article
Publisher
The Company of Biologists Ltd
Topic
- Zoology
Keywords
- color vision
- butterfly
- Heliconius erato
- filter pigment
- insect
- opsin
Status
Published
Research group
- Lund Vision Group
ISBN/ISSN/Other
- ISSN: 1477-9145