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Evolution of the eye’s oxygen supply

Comparative and evolutionary physiology utilises trait variation among species to understand how different organ systems have evolved to support the very different requirements that organisms face in their natural environment. This approach helps us to understand the evolution of life, but also gives a better understanding of many physiological problems in general. An example under study right now is:

Visual perception of the world requires energy, which must be sustained by a constant oxygen supply to the light-absorbing retina of the eye. Yet, the retina of most sharp-sighted animals does not possess internal capillary beds to supply oxygen, as most other tissues do, so adequate oxygen delivery by simple diffusion seems fundamentally impossible. This project investigates putative pathways for oxygen and energy distribution within retinal cells using physiological, biochemical, and molecular tools. By examining those pathways in the retina in a broad spectrum of vertebrate species, this project seeks to identify the physiological mechanisms underlying the evolution of superior vision across vertebrates.

Evolution of retinal capillaries mapped on the mammalian phylogeny
Illustration: Christian Damsgaard

Evolution of retinal capillaries mapped on the mammalian phylogeny. Additional retinal capillaries evolved independently multiple times during mammalian evolution and were secondarily lost in lineages that became less reliant on vision, such as echolocating bats.