This article has been reviewed according to Science X's editorial process and policies. Editors have highlighted the following attributes while ensuring the content's credibility: Evolution is driven by changes in DNA that sometimes promote adaptation, altering traits like disease resistance or reproduction. Often, these changes are minuscule, modifying a single letter in the DNA code—somewhat like altering a single letter on one page of a long book.
In other cases, the change is much more substantial. Whole-genome duplication (WGD) "copy-pastes" an organism's full genetic sequence, meaning there are now two copies of the entire book. Over time, the extra gene copies created by WGD may take on new roles, changing how or when they are expressed.
In this way, WGD provides evolution with more genetic material to work with. With duplicate gene copies available, evolution can edit or repurpose some sections of the "book" while preserving others, creating opportunities for traits to evolve. WGD events have occurred at key stages of evolution, including in the ancestor of all living vertebrates more than 500 million years ago.
However, when these events are so ancient, it's difficult for scientists to uncover many details about how WGD shaped evolution. Atlantic salmon and rainbow trout (both members of the salmonid family) provide a rare opportunity to study these processes in detail. One of the lead authors of a new study, professor Sigbjørn Lien of the Norwegian University of Life Sciences, explains, "The ancestor of salmonids experienced WGD around 100 million years ago, and many duplicated genes are still in the process of being retained, lost or repurposed.
Because of this, the genomes of these fish contain clearer traces of WGD compared to most other vertebrates, and thereby offer a unique window into how evolution unfolds after WGD." In the new study, researchers generated and analyzed huge volumes of genomic data from salmon and trout to track how and when genes are switched on and off across tissues and during early development. "Our study produced close to 800 high-quality sequencing datasets and 80 billion pairs of DNA sequences, providing highly detailed maps of gene activity and regulation for both species. This was a huge team effort achieved via the AQUA-FAANG project, a €6 million EU-funded collaboration involving many research organizations and industry partners across Europe," Lien adds.
The gene activity maps generated in the study depict which genes are switched on or off to control key biological processes in the fish, such as development, and the genetic mechanisms behind these switches. The research team discovered which features of gene activity have remained most stable over time and which have been freest to evolve following WGD. Professor Dan Macqueen of the Roslin Institute at the University of Edinburgh, the study's overall lead, explains, "How the duplicated DNA sequences created by WGD evolve to shape gene expression is a fascinating subject, but not easy to study.
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