Scientists have solved the mystery of why these asexual animals didn’t go extinct

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A tiny species of beetle mite, barely a fifth of a millimeter in size, has helped scientists prove that animals can survive for a very long time without having sex.

Oppiella nova is an all-female species and represents something scientists call an “ancient asexual scandal”. They couldn’t understand how the beetles managed to reproduce without having sex, so assuming they had to hide from the prying eyes of biologists.

“There might be, for example, some sort of ‘cryptic’ sexual exchange that is not known. Or don’t know yet ”, says the first author of study Dr Alexandre Brandt.

“For example, very rarely could a breeding male be produced after all – maybe even ‘by accident’.

Long-term survival of animal species without sexual reproduction was considered virtually impossible – until now.

What scientists at the Universities of Cologne and Göttingen have found is that the mite Oppiella nova has survived thousands – if not millions – of years without having sex.

This animal can clone itself instead of reproducing

Normally there is a big evolutionary advantage of having two parents. In animals with two sets of chromosomes, including humans, sex ensures that our genetics are “mixed” offering diversity.

This means, on average, that the two sets of genetic information we have remain very similar but that there are differences between individuals. This genetic diversity is what allows most life on earth to adapt over time, changing characteristics that best suit our environments.

But this “mixing” does not occur in organisms which reproduce asexually. Although they essentially produce clones of themselves, they are still able to introduce genetic variations and adapt to their environment in a different way.

The two copies of their genetic information accumulate distinct mutations, evolving completely independently. This is called the Meselon effect and is only found in species that only reproduce asexually.

“It may sound simple. But in practice, the Meselson effect has never been conclusively demonstrated in animals – until now, ”explains Professor Tanja Schwander from the Department of Ecology and Evolution at the University of Lausanne.

Survival of a species for such a long time without sexual reproduction is rare but as the study has shown, not impossible.

The team of biologists and zoologists still think the little beetle might have some surprises in store for them when it comes to understanding how sexless evolution works.


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