From the fundamental concepts of biology, the fact that all organisms now alive share a common ancestor (LUCA) ranks as one of my favorites. When I pause to consider that, despite four billion years of evolution and divergence, my ribosomal RNA shares some stretches of sequence identity with all other autonomous organisms, I still get goose bumps. Thus, it should come as no surprise that the only decoration I placed on the wall behind my office desk was a metal sculpture depicting this universal phylogeny. Specifically, it was the Norm Pace 1997 version of the Tree of Life. Just like the process they represent, such phylogenetic trees evolve as new knowledge of Earth's natural history accrues. The relatively recent placement of LECA (Last Eukaryote Common Ancestor) nested within the Asgard Archaea is a wonderful example of the excitement that accompanies the ongoing evolution of the Tree of Life. A mere glance at a modern Tree of Life depiction will immediately convey its meaning to any evolution aficionado. But let's face it. To the uninitiated, phylogenetic trees are just line drawings that require thousands of words to understand.
Fortunately, there is now a new version of the Tree of Life that I feel will greatly facilitate teaching and discussing the evolutionary process and the extent of biodiversity, particularly when it comes to microbes. If, as the saying goes, a picture is worth a thousand words, then putting one hundred drawings on a Tree of Life is worth... Well, one hundred thousand words! OK, I exaggerate. Yet I think the effect of including organismal drawings in a Tree of Life should render the representation much more approachable to students of all ages and from all fields. Basile Beaud has done just that. Basile, who goes by the pseudonym "Bacille Diderm Beaud" on Twitter and is currently a Ph.D. student in Simonetta Gribaldo's lab at the Pasteur Institute, came up with a striking version of the Tree of Life that includes organismal drawings. You can begin to see them by clicking on the figure, but please refer to the high-resolution PDF to really appreciate the artwork. Simonetta also provided a fine Twitter thread describing the tree. Several things became immediately apparent to me on my first glance at this tree. Prime among them are the huge gaps in knowledge due to lack of culturing, depicted by short double helices next to numerous phyla, and the stunning diversity of shapes in what was once called "Monera" by Haeckel, because of its perceived "simplicity." I urge you to take some time and study this tree, put it to good use in learning and teaching. One last thing. From just looking at the diagram I can venture to say that Basile probably had much fun making it (for example, inserting the image of Carl Woese, can you spot it?). Kudos to you Basile!
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