Big eyes cost a lot – forskning.se

During the course of evolution, organisms have evolved in different ways depending
on the environment and what it takes to be the best suited to his
surroundings. To have a well-developed brain has been in research long
associated with great energy metabolism. This means that animals
develops sophisticated nervous systems also require environments where this is
possible. There must be good access to nutrition, and each
investment in a body made at the expense of another organ system that
is not needed as much in that particular environment. So far there have been few
concrete measurements of how high the cost of a nervous system is.

A group of researchers at Lund University have now made measurements in a vertebrate and for the first time calculated how much it actually costs to have a well-developed vision. Scientists have studied the Mexican cave fish that has been lost, that is, back formed, their eyes.

The difference is clear when comparing a ytlevande variety, called morph, of the species. The ytlevande morph has both large eyes, but also much greater access to food, something the cave alive morph does not have. Cave fish live instead in a very dark, nutrient-poor environment, and has no use of his eyes.

– Our measurements in the Mexican cave fish shows that the visual system requires between 5 percent and 15 percent of the animal’s total energy budget, depending on the age of the fish. This is a staggering high cost! This morph during evolution lost both eyes and synbark, no doubt because of the unsustainable energy required to maintain a sensory system that has no importance whatsoever, says Damian Moran, one of the researchers behind the study.

– animals with large and well-developed eye, necessary for their survival, are paying dearly for them. Since all animals have a strictly limited energy budget, a large energy investment in the visual system only at the expense of other organ systems, says Eric Warrant, researchers in functional zoology at the University of Lund.

The researchers were surprised that the visual system of the Mexican cave fish requires such a large proportion of the fish’s total energy budget, the cost was much greater than expected. The study therefore opens up even more opportunities to understand evolution and what is critical to an arts development.

The study has been published in Science Advances.