Just a reminder, there are more eukaryotes than just metazoans

Mar 17 2014 Published by under [Education&Careers]

I've made this point numerous times before, but it bears repeating: Eukaryotic diversity is NOT just the living things you see around you. Yes, everyone likes cute fuzzy animals and will acknowledge that plants and fungi are tasty and probably important, but that's about where people stop. Part of this is because of our tendency to stick with what we can observe and part is because it gets reinforced all the damn time! Even in places that should know better.

I bring this up again this morning because I happened to catch last night's episode of Cosmos, which was centered on evolution. I'm not a Cosmos fanboi and only new it was on because half my twitter feed was drooling in anticipation, but overall I enjoyed it. Sure, there were some odd things about the presentation of some facts, but they got way more right than wrong. As I said at the time, I thought the episode was infinitely more effective the Bill Nye's circus creationist debate. I loved the contrast between natural selection and artificial, and the deconstruction of the Too Complex argument. They unquestionably targeted fav hobby horses of the creationist movement and broke them down, one after the other.

BUT. That freakin' "Tree of Life" (which was conveniently pictured on a real tree, as if the metaphor needed to be sold any harder). As Dr. Tyson's voice over discussed all the diversity of life and complex forms, we were treated to one animal after another popping out of each branch. At the end they added one plant and one mushroom, just to cover the bases.

This isn't a new problem, not at all. In fact, 96% of described species are animals, land plants or fungi. However, if you look at the DNA present in all sorts of different environmental samples, those lineages only account for about 24% of the actual eukaryotic organisms present. While we really like to describe new species of beetles and butterflies, we're often ignoring the majority of what is out there and usually of the more critical players of an ecosystem.

So the next time someone says they looked at something "in a huge variety of eukaryotes, from mice to YEAST!" ask them when they plan to look at the remaining 90% of eukaryotic diversity.

11 responses so far

  • becca says:

    Screw eukaryotes entirely. Biochemical diversity wise, prokaryotes are the world.

  • Mikka says:

    Fuck your eukaryotes and prokaryotes, viruses are the dominant life form on this planet.

  • Stelios says:

    Hey man, you put in the same category beetles and butterflies -- not sure how I feel about that. I would rather describe a nematode than a butterfly.

  • proflikesubstance says:

    Meh, all the same to me.

  • Isabel says:

    Yes it would have been a good opportunity to illustrate that all those metazoans would be on one branch of this great tree. I was also disappointed by the ending transformation of one extant organism into another. Noooooooooooo! Instead a wormlike creature should have transformed in all directions into all those creatures.

  • FunnyFishes says:

    Yeppers, we have a nasty habit of pruning the Tree to a shape we can see with our unaided eyeballs.
    Wonder what a solution is...better hands-on microscope literacy in schools? Cause you can throw as many branches on a phylogeny as you want (and flash as many photos too); I think people need to engage with the microscopic world to build even a basic mental picture of it.
    Something more than the typical one-time pond water survey many classes do...
    I guess phylogenetic literacy is at the heart of the issue too—most people, I'll wager, never see more than the typical highly-pruned Tree of Life-type trees. For them, there are no other lineages, the branches you and I know are there that get no attention.

  • drugmonkey says:

    A quarter? Good enough for govmnt work, eh?

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  • Paul Orwin says:

    Viruses may have the numbers, but since they can't live without the cells, I think they lose. And we don't say prokaryotes anymore. Eubacteria FTW, although the Archaea-ologists may dispute that on the grounds that they charge in where bacteria fear to tread...
    But all of us poor sad microbiologists are used to the abuse and ignorance. We just calmly sip our beer, eat our cheese, and let y'all keep talking about your cute and cuddly things.
    (and don't get me started on symbioses!)

  • Robert L Bell says:

    For the benefit of those visitors who are not biologists, could you please put in a sentence or two that would educate us as to eukaryotes that are note metazoans?

    I would Google it myself, but the spleen vent appears to have dissolved my fingers.

  • Mikka says:

    Actually screw viruses too. If an alien race came to earth, took the biosphere and put it in a blender and then did a metagenomics study with alien solexa technology, they would conclude that the dominant replicator on earth are transposons.


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