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Some animal species can survive successfully without sexual reproduction: study – CTV News

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TORONTO —
An international team of researchers have found that some animals can survive over very long periods of time — possibly millions of years — without sexual reproduction.

By studying a tiny beetle mite species, just one-fifth of a millimetre in size, scientists found that asexual reproduction can be successful in the long term.

The study authors note that until now, the survival of an animal species over a geologically long period of time without sexual reproduction was considered very unlikely, if not impossible.

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Asexual reproduction involves one parent and produces offspring that are genetically identical to each other and the parent, while sexual reproduction involves two parents and produces offspring that are genetically unique.

Using the Oppiella nova beetle mite, an all-female species, researchers from the Universities of Cologne and Göttingen, the University in Lausanne in Switzerland and the University of Montpellier in France, demonstrated for the first time the so-called Meselson effect in animals.

According to the study, the Meselson effect is a characteristic trace in the genome of an organism that suggests “purely asexual reproduction.”

In the study, researchers looked at different populations of the Oppiella nova and the closely related, but sexually reproducing species, Oppiella subpectinata in Germany and sequenced their genomes. The study found that the sequencing of the Oppiella nova genomes showed the Meselson effect.

The findings were published Tuesday in peer-reviewed scientific journal PNAS.

Scientists had previously considered the Oppiella nova species an “ancient asexual scandal” as they couldn’t determine how the beetles were managing to reproduce without having sexual intercourse.

Initially, the study notes that biologists thought these beetles were hiding their acts of reproduction.

“There could be, for example, some kind of ‘cryptic’ sexual exchange that is not known. Or not yet known,” first author of the study Alexander Brandt of the University of Lausanne said in a press release.

“For example, very rarely a reproductive male could be produced after all — possibly even ‘by accident’,” he added.

However, the Oppiella nova beetle mite clones itself rather than reproducing, according to the study.

Researchers say the existence of ancient asexual animal species can be difficult to explain as asexual reproduction can seem “very disadvantageous” in the long term due to a lack of genetic diversity.

Biologists say there is typically an “evolutionary advantage” to having two different genomes that only a pair of parents can supply. Through sexual reproduction, this ensures a “constant ‘mixing’ of the 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, evolving characteristics that best suit the changing environment.

Researchers also found that it is possible for asexually reproducing species to introduce genetic variance into their genomes and thus adapt to their environment during evolution, despite producing genetic clones of themselves.

Scientists say that lack of “genome mixing” compared to sexual species causes the two genome copies of asexual animals to accumulate separate mutations and evolve independently over time.

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 could still provide a surprise or two,” Jens Bast, junior research group leader at the University of Cologne, said in the press release.

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Giant prehistoric salmon had tusk-like teeth for defence, building nests

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The artwork and publicity materials showcasing a giant salmon that lived five million years ago were ready to go to promote a new exhibit, when the discovery of two fossilized skulls immediately changed what researchers knew about the fish.

Initial fossil discoveries of the 2.7-metre-long salmon in Oregon in the 1970s were incomplete and had led researchers to mistakenly suggest the fish had fang-like teeth.

It was dubbed the “sabre-toothed salmon” and became a kind of mascot for the Museum of Natural and Cultural History at the University of Oregon, says researcher Edward Davis.

But then came discovery of two skulls in 2014.

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Davis, a member of the team that found the skulls, says it wasn’t until they got back to the lab that he realized the significance of the discovery that has led to the renaming of the fish in a new, peer-reviewed study.

“There were these two skulls staring at me with sideways teeth,” says Davis, an associate professor in the department of earth sciences at the university.

In that position, the tusk-like teeth could not have been used for biting, he says.

“That was definitely a surprising moment,” says Davis, who serves as director of the Condon Fossil Collection at the university’s Museum of Natural and Cultural History.

“I realized that all of the artwork and all of the publicity materials and bumper stickers and buttons and T-shirts we had just made two months prior, for the new exhibit, were all out of date,” he says with a laugh.

Davis is co-author of the new study in the journal PLOS One, which renames the giant fish the “spike-toothed salmon.”

It says the salmon used the tusk-like spikes for building nests to spawn, and as defence mechanisms against predators and other salmon.

The salmon lived about five million years ago at a time when Earth was transitioning from warmer to relatively cooler conditions, Davis says.

It’s hard to know exactly why the relatives of today’s sockeye went extinct, but Davis says the cooler conditions would have affected the productivity of the Pacific Ocean and the amount of rain feeding rivers that served as their spawning areas.

Another co-author, Brian Sidlauskas, says a fish the size of the spike-toothed salmon must have been targeted by predators such as killer whales or sharks.

“I like to think … it’s almost like a sledgehammer, these salmon swinging their head back and forth in order to fend off things that might want to feast on them,” he says.

Sidlauskas says analysis by the lead author of the paper, Kerin Claeson, found both male and female salmon had the “multi-functional” spike-tooth feature.

“That’s part of our reason for hypothesizing that this tooth is multi-functional … It could easily be for digging out nests,” he says.

“Think about how big the (nest) would have to be for an animal of this size, and then carving it out in what’s probably pretty shallow water; and so having an extra digging tool attached to your head could be really useful.”

Sidlauskas says the giant salmon help researchers understand the boundaries of what’s possible with the evolution of salmon, but they also capture the human imagination and a sense of wonder about what’s possible on Earth.

“I think it helps us value a little more what we do still have, or I hope that it does. That animal is no longer with us, but it is a product of the same biosphere that sustains us.”

This report by The Canadian Press was first published April 24, 2024.

Brenna Owen, The Canadian Press

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Giant prehistoric salmon had tusk-like spikes used for defence, building nests: study

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A new paper says a giant salmon that lived five million years ago in the coastal waters of the Pacific Northwest used tusk-like spikes as defense mechanisms and for building nests to spawn.

The initial fossil discoveries of the 2.7-metre-long salmon in Oregon in the 1970s were incomplete and led researchers to suggest the fish had fang-like teeth.

The now-extinct fish was dubbed the “saber-tooth salmon,” but the study published in the peer-reviewed journal PLOS One today renames it the “spike-toothed salmon” and says both males and females possessed the “multifunctional” feature.

Study co-author Edward Davis says the revelation about the tusk-like teeth came after the discovery of fossilized skulls at a site in Oregon in 2014.

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Davis, an associate professor in the department of earth sciences at the University of Oregon, says he was surprised to see the skulls had “sideways teeth.”

Contrary to the belief since the 1970s, he says the teeth couldn’t have been used for any kind of biting.

“That was definitely a surprising moment,” Davis says of the fossil discovery in 2014. “I realized that all of the artwork and all of the publicity materials … we had just made two months prior, for the new exhibit, were all out of date.”

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SpaceX sends 23 Starlink satellites into low-Earth orbit

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April 23 (UPI) — SpaceX launched 23 Starlink satellites into low-Earth orbit Tuesday evening from Space Launch Complex 40 at Cape Canaveral Space Force Station in Florida.

Liftoff occurred at 6:17 EDT with a SpaceX Falcon 9 rocket sending the payload of 23 Starlink satellites into orbit.

The Falcon 9 rocket’s first-stage booster landed on an autonomous drone ship in the Atlantic Ocean after separating from the rocket’s second stage and its payload.

The entire mission was scheduled to take about an hour and 5 minutes to complete from launch to satellite deployment.

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The mission was the ninth flight for the first-stage booster that previously completed five Starlink satellite-deployment missions and three other missions.

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