Geneticists have discovered a past whole-genome duplication (WGD) event in the common ancestor of sturgeons and scallops that occurred just before a significant mass extinction, potentially providing these species with advantageous genetic variation. This finding also raises the possibility of similar neglected WGDs in the lineages of other species that may have contributed to survival during periods of extreme environmental change.
Geneticists have made a significant discovery about the ancient history of sturgeon and oarfish that has profound implications for our understanding of evolution. They identified a previously hidden instance of a “whole genome duplication” (WGD) in the shared ancestor of these The big-picture finding hints at the possibility of multiple undiscovered, shared WGDs in other species, preceding periods of drastic environmental upheaval throughout Earth’s tumultuous history.
The research, led by Professor Aoife McLysaght and Dr Anthony Redmond from Trinity College Dublin’s School of Genetics and Microbiology, has just been published in the leading international journal, Professor Aoife McLysaght said: “Whole genome duplication is exactly what it sounds like – it’s a fascinating evolutionary event where the whole genome is copied and pasted so that a species suddenly has twice as much genetic material as before. While most species, like us, are “diploid”—having pairs of chromosomes, one from each parent—after the whole genome is duplicated, everything is in four copies. This effectively provides a lot of raw material for mutations to occur – and evolution. Eventually, the genome of a species will return to typical pairings through a process called rediploidization.
“We’ve known about whole-genome duplication and re-ploidization for a long time, but what’s new and exciting is that we’ve shown that the time it takes to complete the second part of the process is very important.” In this case, it took a long, long time—so long that some gene duplications appear to be species-specific, arising after the two species took different paths on the tree of life.
“As a result, the ancient initial whole-genome duplication that occurred before the separation of species has been missed until now. We believe that the same thing may have happened in many other lineages of species, and this is important given the possibility that it generated genomic conditions that helped species survive mass extinctions.
Genetically, sturgeons and paddlefish show evidence of shared and unshared gene duplications that themselves derive from the ancient WGD, which, when marked just over 250 million years ago, places it just before the Permian-
Dr Anthony Redmond said: “Multiple genome-wide duplication events are known for our ancient early vertebrate ancestors and they have shaped the landscape of our modern human genome.
“Our findings are exciting because, in addition to shedding light on sturgeon and copepod genome evolution, they provide a comparative snapshot of how our early vertebrate ancestors’ genomes and duplicated genes evolved after these duplication events.”
Reference: “Independent Rediploidization Masks Share a Whole Genome Duplication in the Sturgeon Ancestor” by Anthony C. Redmond, Dearbhale Casey, Manu Kumar Gundappa, Daniel J. McQueen and Aoife McLysaght, 19 May 2023, Nature Communications.
DOI: 10.1038/s41467-023-38714-z
The study was funded by the Irish Research Council and the European Research Council.