An Il­lus­trated Tree

by Roberto

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.
 

Fig. 1. The Tree of Life by Basile Beaud. Source

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 (@babebe.bsky.social on Bluesky) 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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