Geneticists discover hidden 'whole genome duplication' that may explain
why some species survived mass extinctions

Date:
May 31, 2023
Source:
Trinity College Dublin
Summary:
Geneticists have unearthed a major event in the ancient history
of sturgeons and paddlefish that has significant implications for
the way we understand evolution. They have pinpointed a previously
hidden 'whole genome duplication' (WGD) in the common ancestor
of these species, which seemingly opened the door to genetic
variations that may have conferred an advantage around the time
of a major mass extinction some 200 million years ago.


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==========================================================================
FULL STORY ========================================================================== Geneticists have unearthed a major event in the ancient history of
sturgeons and paddlefish that has significant implications for the way
we understand evolution. They have pinpointed a previously hidden "whole
genome duplication" (WGD) in the common ancestor of these species, which seemingly opened the door to genetic variations that may have conferred
an advantage around the time of a major mass extinction some 200 million
years ago.

The big-picture finding suggests that there may be many more overlooked,
shared WGDs in other species before periods of extreme 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 leading international journal, Nature Communications.

Professor Aoife McLysaght said: "Whole genome duplication is exactly
as it sounds -- it's a fascinating evolutionary event where an entire
genome is copied and pasted so that a species suddenly has twice the
genetic material as it did before. Whereas most species, like us, are
'diploid' -- having pairs of chromosomes, one from each parent -- after
whole genome duplication everything is in four copies. This effectively provides a lot of raw material for mutations -- and evolution -- to
occur. Eventually, a species genome will revert to the typical pairs
through a process called rediploidisation.

"We've know about whole genome duplication and rediploidisation for a
long time but what is new, and exciting, is that we have shown that the
time it takes for the second part of the process to complete is very
important. In this case, it took a long, long time -- so long that some
gene duplications appear to be species-specific, occurring after the
two species went their separate ways on the tree of life.

"As a result, the ancient original whole genome duplication that happened before the species had separated had been missed until now. We believe the
same thing might have happened in many other species lineages and that
is important given the possibility that it generated genomic conditions
that helped the species survive mass extinctions." Genetically,
sturgeons and paddlefish show evidence of shared and non-shared gene duplications that were themselves derived from the ancient WGD, which,
when timestamped to just over 250 million years ago places it just before
the Permian-Triassic mass extinction that wiped out over half of the
families of all living things.

This would seem to add more weight to the theory that WGD events provide species with more of an evolutionary canvas to work with; more genetic
material means more capacity for variations over a given time, and that
in turn increases the chance of some conferring an advantage to cope with difficult or changing environmental conditions. These would certainly have
been in evidence during the period of rediploidisation that overlapped
with the Triassic- Jurassic mass extinction around 200 million years ago.

Dr Anthony Redmond said: "Multiple whole genome duplication events
famously occurred in our ancient early vertebrate ancestors and these
have shaped the landscape of our modern human genome.

"Our findings are exciting because as well as shining a light on sturgeon
and paddlefish genome evolution, they provide a comparative snapshot of
how our early vertebrate ancestors genome and duplicated genes evolved
after these doubling events."
* RELATED_TOPICS
o Plants_&_Animals
# Extinction # Evolutionary_Biology # New_Species
o Earth_&_Climate
# Exotic_Species # Environmental_Policy #
Environmental_Awareness
o Fossils_&_Ruins
# Evolution # Fossils # Early_Humans
* RELATED_TERMS
o Extinction_event o Permian-Triassic_extinction_event o
Toba_catastrophe_theory o Timeline_of_evolution o Dinosaur
o Cretaceous-Tertiary_extinction_event o Jurassic o
Timeline_of_human_evolution

========================================================================== Story Source: Materials provided by Trinity_College_Dublin. Note:
Content may be edited for style and length.


========================================================================== Journal Reference:
1. Anthony K. Redmond, Dearbhaile Casey, Manu Kumar Gundappa, Daniel J.

Macqueen, Aoife McLysaght. Independent rediploidization masks shared
whole genome duplication in the sturgeon-paddlefish ancestor. Nature
Communications, 2023; 14 (1) DOI: 10.1038/s41467-023-38714-z ==========================================================================

Link to news story: https://www.sciencedaily.com/releases/2023/05/230531150053.htm

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