Early evolution of multifocal optics for well-focused colour vision in vertebrates.
Author
Summary, in English
Jawless fishes (Agnatha; lampreys and hagfishes) most closely resemble the earliest stage in vertebrate evolution and lamprey-like animals already existed in the Lower Cambrian [about 540 million years ago (MYA)]. Agnathans are thought to have separated from the main vertebrate lineage at least 500 MYA. Hagfishes have primitive eyes, but the eyes of adult lampreys are well-developed. The southern hemisphere lamprey, Geotria australis, possesses five types of opsin genes, three of which are clearly orthologous to the opsin genes of jawed vertebrates. This suggests that the last common ancestor of all vertebrate lineages possessed a complex colour vision system. In the eyes of many bony fishes and tetrapods, well-focused colour images are created by multifocal crystalline lenses that compensate for longitudinal chromatic aberration. To trace the evolutionary origins of multifocal lenses, we studied the optical properties of the lenses in four species of lamprey (Geotria australis, Mordacia praecox, Lampetra fluviatilis and Petromyzon marinus), with representatives from all three of the extant lamprey families. Multifocal lenses are present in all lampreys studied. This suggests that the ability to create well-focused colour images with multifocal optical systems also evolved very early.
Department/s
Publishing year
2008
Language
English
Pages
1559-1564
Publication/Series
Journal of Experimental Biology
Volume
211
Issue
10
Document type
Journal article
Publisher
The Company of Biologists Ltd
Topic
- Zoology
Keywords
- longitudinal spherical aberration
- longitudinal chromatic aberration
- lens
- multifocal
- colour vision
- evolution
- lamprey.
Status
Published
ISBN/ISSN/Other
- ISSN: 1477-9145