Who is studying the rest of the eukaryotes? The protistologists!


Pearson et al. on Foraminifera

It is a cabinet of marvels where Russians draw meticulous illustrations of spines and spikes, where mitochondria are optional but always leave their shadow, where roots are elusive, basic biochemical pathways variable, and new discoveries can be made at the phylum level.

Yes, I’m in Seville at the VIIth European Congress of Protistology meeting with the International Society of Protistologists, 5 – 10 September 2015, right over the American Labor Day, along with several hundred others.


Sandie Baldauf, my guide and mentor at this meeting and her amazing grad student, Sanea Sheikh

We’ve heard of amoebas, even of social amoebae like Dictyostelium. We have heard of diatoms and of malaria. Why we even know about brain-eating Naegleria and gut-wrenching Girarida. But there are so, so many more. What do the people that study them do?IMG_8104 IMG_8105 IMG_8087

It is not mostly about social behavior, nor even mostly about symbiosis, two topics that entrance me. A lot of these lovely organisms are in water, sweet or salt. They may be deep in mud sediments, or floating in the ocean. One might eat the others. They help us get rid of our shit, literally. How do people study them?

First, it seems they draw them, those that have tests, hard shells of exotic shapes. People have dedicated their lives to these drawings. They have devised ways of categorizing them visually. They have named them. But form is easy to evolve, so phylogenies based on shapes are easily disproven with the hard accuracy of molecular phylogenies. But even these can confuse.

These phylogenies are included in maybe a third of all presentations. They are based on ribosomal 18s genes, on ITS, and on many other genes. But these lovely critters have stolen genes from others all too often in the sea of life, so a well sequenced gene could still be a historical lie. How to tell? I’m still learning, but one way is to do phylogenies gene by gene. If your gene is at odds with what the other genes tell you for a species, you have to wonder and adjust.

What happens with the mitochondria is another big question. Which of the hundreds of genes needed to run a mitochondrion have fled to the big machine of the nucleus? Is this conserved? Apparently not.

Biochemical pathways are a big deal including both oxygenated and anaerobic ones. These protistologists are experts in cross-disciplinary studies, speaking biochemistry, systematics, ecology, and art.

Protistology is profoundly impacted by the genomic revolution since these generally small genomes can efficiently reveal a great deal, since behavior, or even wild observation are not options. Bar coding and environmental sampling is changing our view of what is where and why.

My own little branch of the tree of life is covered by this meeting, the Dictyostelids, but what a small piece it is. It makes me wonder why this group alone evolved and speciated its lovely multicellular fruiting body shapes. But there are bigger things to wonder about. Why didn’t more protists sprout lineages like animals? I don’t know if we’ll ever get answers to these historical questions. We certainly won’t without more of this fascinating work on the foundations of the ancient eukaryote collaboration, something that also arose only once.


About Joan E. Strassmann

Evolutionary biologist, studies social behavior in insects & microbes, interested in education, travel, birds, tropics, nature, food; biology professor at Washington University in St. Louis
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