TORONTO – An international team of researchers has found that some animals can live very long – possibly millions of years – without sexual reproduction.
By studying a small beetle mite species, just one-fifth of a millimeter in size, scientists found that asexual reproduction can be successful over the long term.
The study authors note that until now, the existence of animal species without sexual reproduction for a geologically long time was considered impossible, if not impossible.
Asexual reproduction involves one parent and produces offspring that are genetically identical to each other and the parent, whereas sexual reproduction involves two parents and produces offspring that are genetically identical to each other. are unique.
Using the Opiella nova beetle mite, an all-female species, researchers from the Universities of Cologne and Göttingen, the University of Lausanne in Switzerland and the University of Montpellier in France demonstrated the so-called Messelson effect in animals for the first time.
According to the study, the Messelson effect is a specific mark in an organism’s genome that suggests “purely asexual reproduction”.
In the study, researchers looked at different populations of Oppiella nova and a closely related, but sexually reproducing species, Oppiella subpectinata in Germany, and sequenced their genomes. The study found that sequencing of the Opiella nova genome showed the Messelson effect.
The findings were published on Tuesday Peer-Reviewed Scientific Journal PNAS.
Scientists previously considered the Opiella nova species to be an “ancient asexual scam” because they could not determine how the beetles were reproducing without mating.
Initially, the study states that biologists thought these beetles were hiding their functions of reproduction.
“For example, there may be some kind of ‘secret’ sexual exchange that is not known. or is not yet known,” said study first author Alexander Brandt from the University of Lausanne. Press release.
“For example, very rarely a breeding male can be produced – possibly even ‘by accident’,” he said.
However, according to the study, the Oppiella nova beetle mite clones itself rather than reproduces.
Researchers say the existence of ancient asexual animal species can be difficult to explain because a lack of genetic diversity can make asexual reproduction seem “very disadvantageous” in the long run.
Biologists say that there is generally an “evolutionary advantage” to having two separate genomes that only one pair of parents can supply. Through sexual reproduction, it ensures a “continuous ‘mixing’ of two copies” of the genome in each of their cells.
This means that the two sets of genetic information remain very similar, but there are differences that allow organisms on Earth to adapt over time, developing traits that are best suited to the changing environment.
The researchers also found that it is possible for asexually reproducing species to introduce genetic variation into their genomes and thus adapt to their environment during evolution, despite creating genetic clones of their own.
The two genome copies of asexual animals accumulate different mutations and evolve independently over time due to the lack of “genome mixing” compared to sexual species, scientists say.
While the survival rate of a species without sexual reproduction is quite rare, scientists conclude that it is not impossible.
“Our results clearly show that O. nova reproduces exclusively asexually. When it comes to understanding how evolution works without sex, these beetle mites still provide a surprise or two. can,” said Jens Bast, junior research group leader at the University of Cologne. In press release.