You Are Here (The Circle of Phylogenetics)

Phylogenetics is the study of the relatedness of organisms. In other words, scientists look at physical traits (morphology) and (more recently) DNA sequences to determine which organisms have more in common that others. Even if you’ve never heard of phylogenetic taxonomy before, you’re already familiar with some basic separations, such as between animals and plants. The Tree of Life has some nice illustrations, but I thought this circular phylogenetic tree was especially cool:


This circular tree, which was published in Science, Shows relationships between representatives of all species on Earth. It was developed by David M. Hillis, Derrick Zwickl, and Robin Gutell at the University of Texas. As they state on their website (where the full pdf file is available- a really cool thing to zoom in and out on!) the tree is:

“an analysis of small subunit rRNA sequences sampled from about 3,000 species from throughout the Tree of Life. The species were chosen based on their availability, but we attempted to include most of the major groups, sampled very roughly in proportion to the number of known species in each group (although many groups remain over- or under-represented). The number of species represented is approximately the square-root of the number of species thought to exist on Earth (i.e., three thousand out of an estimated nine million species), or about 0.18% of the 1.7 million species that have been formally described and named.”

Here’s a closeup of the Animals section:

The arrow below points to humans:


And one final zoom in:

This reminds me of a quote from Tim Rice that ended up in my Developmental Biology textbook:

“It’s the circle of life, and it moves us all.”


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