Ivy Mead
28 March 2011
Bioinformatics
Paper for 23 March2011
The evolution of vision provides many interesting and important questions to molecular
evolutionists, the answers of which can provide better methods of exploring evolution in whole.
One might think that in many cases that genes encoding proteins for vision are strongly
conserved, because the system is so vital and works perfectly well in many cases. However,
many examples have been found in nature where organisms have produced a unique phenotype
based on the pressures of the environments they evolved in. One paper stated that this is in part
true, at least in nocturnal mammals, because long-wave opsin was found to be strongly
conserved, while the short-wave opsin was very divergent. Both groups of genes are thought to
have been under purifying selection (Zhao et al., 2009). Another paper provided an example of
an organism that developed co-adapted vision to make up for poor visibility in the deep ocean.
The coelacanth have RH1 and RH2 pigments which allow them to see wavelengths 485 nm to
478 nm, their own version of color (Yokoyama, 2002). This example serves as an interesting
example to provide an idea of how diverse vision can be in organisms, even though one might
hypothesize that it would not change too much. Possibly more interesting is the idea that by
studying organisms from a single clade at a molecular level, information on their extinct ancestor
might be found if investigated properly (Yokoyama et al., 2008)
Word count: 237
Works Cited:
Yokoyama, S. (2002). Molecular evolution of color vision in vertebrates. Gene. 300.
Yokoyama, S. et al. (2008). Elucidation of phenotypic adaptations: Molecular analyses of dimlight vision proteins in vertebrates. PNAS. 105: 36.
Zhao, H. et al. (2009). The evolution of color vision in nocturnal mammals. PNAS. 106: 22.