The eye is known to be an energetically costly organ, and our project will use the Mexican blind cave fish to test whether the metabolic cost of the eye has been a significant selective force in the development and regression of sight.
The blind Mexican cave fish is a model species used in developmental biology to study vision. It is particularly useful because it has two morphs: an eyed, surface-dwelling morph, and non-eyed, cave-dwelling morph. The cave-dwelling morph is known to have evolved from the surface-dwelling morph, and in the process of moving into the dark environment the cave-dwelling morph lost its vision.
The question of interest is whether the loss of vision was a passive accumulation of genetic mutations in the eye genes, or an active process of eye degeneration so that energy was not wasted on trying to see in the dark. We hypothesise that latter process has been important in this species. To test this hypothesis we will measure the energy demand (oxygen uptake rate) of the eye using in vivo and in vitro techniques.