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Early evolution of multifocal optics for well-focused colour vision in vertebrates.

Författare:
Publiceringsår: 2008
Språk: Engelska
Sidor: 1559-1564
Publikation/Tidskrift/Serie: The Journal of experimental biology
Volym: 211
Nummer: 10
Dokumenttyp: Artikel
Förlag: Company of Biologists

Sammanfattning

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.

Disputation

Nyckelord

  • Biology and Life Sciences
  • longitudinal spherical aberration
  • longitudinal chromatic aberration
  • lens
  • multifocal
  • colour vision
  • evolution
  • lamprey.

Övriga

Published
Yes
  • ISSN: 0022-0949

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