Phylogeny Friday — 18 July 2008
When they published the initial analysis of the complete platypus genome (doi:10.1038/nature06936), Nature, as they’re wont to do, also put out a news item announcing the major findings (doi:10.1038/453138a). That news article included a phylogeny illustrating the evolutionary relationships of various animal species in various stages of having their complete genomes sequenced.
In your News story ‘Top billing for platypus at end of evolution tree’, the graphic depicting genome status presents a shocking new phylogeny of the Vertebrates — with Archosaurs (birds and crocodilians) and Mammals forming a monophyletic group.
In all honesty, the tree is so craptacularly drawn that it’s hard to say that Archosaurs and Mammals are monophyletic based on the illustration. It looks more like the branching order of most vertebrates (and most animals) is unresolved, but I can definitely understand how Ducey interprets the tree. Either way, Nature did a bad job with this illustration. Why did they suck so bad? Here’s what Ducey thinks:
The bad news is that this dramatic new ‘proposal’ is completely adrift from the research Article by Wesley C. Warren and colleagues that the figurative tree is intended to illustrate, and it continues a persistent tendency in popular literature to portray all evolution as leading towards humans.
Totally! The idea of a great chain of being, starting with bacteria and progressing through animals to humans, permeates much of the popular discussion of evolution. And it’s just not true. It’s a phylogenetic fallacy.
Coincidentally, Ducey points out, Science repeated the same error Nature made. In their coverage of the platypus genome paper (doi:10.1126/science.320.5877.730), Science included this image:
Ouch! At least the tree accompanying the Nature article was ambiguous enough that it could be interpreted to represent the true phylogeny. While the cladogram from Science does not perpetuate the great chain of being myth, it does represent a completely resolved phylogeny that also happens to be incorrect.