Research into the genetics of fish vision has discovered evidence of a little-known alternative form of evolution.

Scientists at QBI working with the University of Basel discovered that a family of genes responsible for blue vision in percomorph fishes—including species such as tuna and anglerfish—has undergone concerted evolution, where related genes stay closely aligned.

The study’s co-lead author, Dr Fabio Cortesi—a visiting scholar to QBI—said the evolutionary path taken by these genes led to them having very similar attributes instead of diverging.

“We found that evolution doesn’t always go as assumed, and a different type of evolution occurred for these genes in these fishes,” Dr Cortesi said.

“If one of the genes started to diverge from the other genes within the family, concerted evolution occurred and it got pulled back in again to where it started, keeping the genes functioning within a limited range.”

QBI’s Professor Justin Marshall said that studying the visual systems of fish provides an insight into human biology as well as aquatic animals.

“Visual systems in land animals are much simpler because our visual environment is quite constant, whereas aquatic animals have to deal with differences in depth and particles in the water, such as sand or algae, creating different levels of light,” Professor Marshall said.

“In our case, the red and green colour receptors arose through a genetic duplication, similar to the new blue gene we found in fishes; however, before these genes split our ancestors were functionally dichromatic, comparable to some colour blind humans nowadays.”

The study was led by the Zoological Institute of the University of Basel, in collaboration with UQ, the University of Olso, The University of Western Australia, and the University of Maryland.

Findings of the research are published in the journal Proceedings of the National Academy of Sciences of the United States of America.