An international team of researchers has mapped the genetic profile of the rainbow trout, focusing on the rate at which genes have evolved since a rare genome doubling event occurred around 100 million years ago.
Using fish bred at Washington State University, the team said the mapping of the versatile salmonoid opens a window into how vertebrates evolve.
“Most of the duplicated genes get lost or modified so much that they are no longer recognizable as duplicates over time. In the trout and salmon we can see an earlier stage in the process and many duplicated genes are still present,” said Gary Thorgaard, a WSU biologist.
Genetic material was taken from the Swanson line of rainbow trout and cloned at WSU to ensure that researchers are looking at the same fish in successive studies.
According to the team’s research, around half of all protein coding genes have been deleted since the rainbow trout’s genetic doubling event. It has also retained almost all its microRNA genes, which help regulate gene expression.
Research also found the fish retained original or nearly original genes involved in embryonic development and development of connections between nerve cells. The timing associated with these changes suggests gene evolution after an event like this is a much slower process than previously thought.
“Some animals, like the lungfish and coelacanth, are ‘living fossils’ that have been around for hundreds of millions of years without changing very much. Others, like the polar bear, seem to have evolved quite recently,” said a team researcher.
“After the trout gene duplication, the process happened more slowly than it has in most other vertebrate animals, and we can still watch it going on,” they added.
The findings will be reported in Nature Communications this week.
