Evolution of colour vision in vertebrates

Numerous gene families are involved in vertebrate vision. We have found that the genome duplications in early vertebrate evolution generated gene duplicates that became specialized in expression in cones or rods, i.e., for colour vision and dim-light vision, respectively. A surprising conclusion from these comparisons is that colour vision seems to have arisen before dim-light vision. We are presently investigating a large number of gene families involved in the phototransduction signalling cascade from the light receptors themselves, the opsins, via transducins and beyond. The mRNA distribution of the gene duplicates in different cell types in the retina is investigated by in situ hybridizations in zebrafish, a species that has retained more of the ancestral colour vision genes than mammals. Furthermore, the zebrafish shares with other teleost fishes the third tetraploidization that has resulted in additional gene duplicates of transducins and other phototransduction gene families. Thus, the tetraploidizations have paved the way for the elaboration of vertebrate vision by supplying additional gene copies that could evolve new functions or more specialized functions.


Project members:

Xesus Abalo
David Lagman
Daniel Ocampo Daza
Christina Bergqvist