YouTube Video Helps Unravel Euglenoid Evolutionary History

YouTube Video Helps Unravel Euglenoid Evolutionary History

Light microscope images of euglenoid cysts from Greece between the Holocene and the present. Researchers recently saw evidence for the first time that euglenoids form cysts.
Andreas Koutsodendris/University of Heidelberg

  • Fabian Weston makes videos of tiny organisms filmed under a microscope.
  • One of his videos provided the missing piece to connect 400-year-old fossils with living euglenoids.
  • Euglenoids may be some of the earliest eukaryotes to include plants and animals.

Sometimes it really helps Google. Especially when you are a scientist who has exhausted all other angles.

After all else failed, a research team did just that. And it helped them solve a scientific mystery that had baffled biologists for decades.

400 million year old microscopic fossils

There have been five mass extinctions on Earth. Some events was killed 95% of living species. Euglenoids survived them all.

“Euglenoids are microscopic life forms that combine both animal and plant characteristics,” Utrecht University geosciences professor Bas van de Schootbrugge told Business Insider via email. They eat like animals and photosynthesize like plants.

You can find the organisms in freshwater ponds all over the world, Van de Schootbrugge said. But although they have been around for ages, they are rarely found in the fossil record.

To find ancient evidence of euglenoids, van de Schootbrugge and his colleagues looked at microfossils – juvenile fossils just a few millimeters in size.

“We worked on the hypothesis that these microfossils might be cysts of euglenoids, but no one had ever seen a euglenoid form cysts in nature or in the laboratory,” Van de Schootbrugge said.

Some euglenoids from 400 million years ago formed cysts that protected the body in adverse conditions. However, it was not clear what these cysts looked like.

A casual look at a YouTube video helped van de Schootbrugge and his colleagues link fossils and living euglenoids.

The finding could help identify euglenoids as some of the most ancient ancestors of all living plants and animals.

The Proof Was in a Pond (and on YouTube)

There were two main problems with cyst microfossils: what they were called and what they looked like.

“People working in different time periods gave different names to basically the same type of microfossil, which obscured their long evolutionary history,” Van de Schootbrugge said.

These were the Paleozoic Chomotriletes, the Mesozoic Pseudoschizaea and the Cenozoic Concentricites. The researchers reviewed 500 articles to find mentions of all the different names.

Van de Schootbrugge said other scientists had noticed similarities between all these microfossils, but “the cysts have a structure unlike anything seen before.” Because no one had documented a euglenoid forming a cyst, there was nothing from the present to compare the ancient examples to.

And then one of van de Schootbrugge’s co-authors, Paul Strother, Googled “Euglena cysts” and a result came up on YouTube.

In the video, Fabian Weston showed a sample of pond water under a microscope. The New South Wales resident has a YouTube channel dedicated to filming all kinds of microscopic organisms.

In the video below, you can see Euglena turning into a ball with a thick, ribbed wall. “Cysts appear layered, and this may be due to the mucus that normally surrounds certain euglenoids,” Van de Schootbrugge said.

“After watching it, we were convinced that the Euglena seen in the video made the structure we saw as a microfossil,” Van de Schootbrugge said.

This was the missing piece.

“What we did was really link to the most recent living forms that tie taxonomic names to living microorganisms,” Strother told Business Insider via email.

They recently published their paper in a peer-reviewed journal Review of Paleobotany and Palynology.

Van de Schootbrugge noted that they have yet to see the Weston cysts themselves and hope to look at the pond’s sediments for Chomotrilete microfossils.

The evolutionary tree of life

Strother believes that this study is a piece of the eukaryotic Tree of Life (eTOL) puzzle. Eukaryotes are the branch of organisms to which all animals and plants belong. Unlike bacteria, their cells have a nucleus.

In other words, they are our earliest eukaryotic ancestors.

Scientists believe that euglenoids could have evolved a billion years ago press release about education. Knowing which eukaryotes evolved first would be a big step toward understanding how they survived for so long.

Unusual wall structure of a Holocene euglenoid cyst from Lake Vouliagmeni, Greece.
Wilson Taylor/University of Wisconsin, Eau Claire

Extending the fossil record of euglenoids this far back in geologic time suggests that they are among the oldest eukaryotes. Strother said, adding that the question “that this work addresses but doesn’t necessarily ‘answer’ is, ‘What species are at the root of eTOL?’

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