Scientists reclassify eukaryotic microorganisms

Scientists reclassify eukaryotic microorganisms
Credit: Shutterstock

One of the biggest scientific challenges is the classification of the natural world, especially the protists, which are eukaryotic microorganisms. While the classification proposed by Sina Adl et al. (2005) was conservative enough to help keep erroneous or premature groupings at bay, an international team of researchers has revised the classification, incorporating latest advances in the use of phylogenomic-scale phylogenetic analyses and increased taxon sampling. The goal? To shed fresh light on the current state of protist diversity and categorisation, and of undiscovered species. The reclassification was presented in the Journal of Eukaryotic Microbiology.

'Protists include traditionally referred to as and algae, some fungal-like organisms, and many other life-forms that do not fit into the old worldview that divided species between ,' said Professor Adl of the University of Saskatchewan in Canada. 'By the 1960s, it had become clear that these species could no longer fit within such a narrow system, yet the first community-wide attempt to rationally categorise all the protists in the natural evolutionary groups was only made in 2005.'

This reclassification puts to rest the technological limitations observed seven years ago. It also introduces and recognises new super groups. 'With environmental genomics we are experiencing a renaissance of new protist discoveries,' explained Professor Adl. 'These new species allow us to better appreciate how little we know about the biodiversity around us and how they contribute to maintaining the planet's chemical balance.'

This new information helps boost our understanding of age-old relationships between protists, their shared ancestry and their links to animals and plants, according to the researchers.

They identified a group connecting animals, and their protist relatives, such as marine choanoflagellates, to protists that are dominated by amoeboid cells, including moulds, algae and tiny crustaceans. The researchers also recognised Stramenopiles, Alveolates, and Rhizaria (SAR), a new supergroup that contains common and successful algae, microbial predators and parasites on our planet. Giant kelp and other brown seaweeds belong to this group, as do living sand grains known as 'forams', and the parasite that causes malaria in people. Studies performed since 2005, namely large-scale deoxyribonucleic acid (DNA) and ribonucleic acid (RNA) sequencing, have indicated that profoundly dissimilar forms are related to each other.

'This new classification, that better reflects how species are related, improves our ability to predict the number of species that remain to be discovered,' concluded Professor Adl. 'There is a huge unknown diversity in the deep sea, but probably even more in the soil we walk on.'

Explore further

Nature's misfits: Reclassifying protists helps us understand how many species remain undiscovered

More information: Adl, S. et al., 'The Revised Classification of Eukaryotes', Journal of Eukaryotic Microbiology, 2012. doi:10.1111/j.1550-7408.2012.00644.x
Provided by CORDIS
Citation: Scientists reclassify eukaryotic microorganisms (2012, October 8) retrieved 20 August 2019 from
This document is subject to copyright. Apart from any fair dealing for the purpose of private study or research, no part may be reproduced without the written permission. The content is provided for information purposes only.

Feedback to editors

User comments

Oct 08, 2012
So 47% of firewood is infested with insects? I read recently that 47% of American's don't pay income tax! Coincidence?

Please guys, honestly, I am kidding. Seriously though, anyone that has every bought/burned firewood that doesn't know they have live insects inside is a few pints short of a quart. Quite aside from any ecological concerns, its the primary reason that stacking firewood up against your house runs the risk of getting insect/rot in the walls. I hope no one still does that anymore.

Oct 09, 2012
Well Parsec I'm unsure as to what triggered your thoughts, however I certainly agree with your statement of NOT stacking firewood against your home. I live in Australia, and termites are everywhere, including all sorts of wood boring insects, not to mention fungi/moulds!!! Anyway back on topic, I'm glad that DNA analysis is revamping the tree of life. I look forward to the day, that every known lifeform is sequenced and placed on the tree of life.
What better way to see how life evolved and to get a better biological nomenclature/classification.

Oct 15, 2012
@parsec - I agree with Ober, that your comment has nothing to do with the article, and makes the exact humor you're dishing out a bit flat. Try to get the topical humor on topic next time.

I have a brick house and a bug guy who sprays every month, so it makes no difference where the firewood (Mesquite wood in my case) is stacked.

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more