Understanding Evolutionary Trees

Since so many discussions here rely on the ability to understand and interpret phylogenies, I wanted to recommend Ryan Gregory’s excellent article, Understanding Evolutionary Trees, which some here may be familiar with already. It gives a brief primer on how to interpret phylogenies and avoid common misconceptions that seriously compromise comprehension and lead to misinterpretations. Enjoy!


My favorite part is the list of misconceptions. I have encountered all of them at one time or another, several of them here on Peaceful Science. Good introduction to tree-thinking.

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Yes, that’s definitely the best part. I’ve also encountered many of the misconceptions out in the wild, mostly while teaching undergrads.

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Can you list out the key misconceptions here?

Here’s the list:

  1. Higher and lower

  2. Main line and side tracks

  3. Reading across the tips

  4. Similarity vs. relatedness

  5. Sibling vs. ancestor

  6. Long branch implies no change or Less diverse equals basal equals ancestral

  7. Different lineage ages for modern species

  8. Backwards time axes

  9. More intervening nodes equals more distantly related

  10. Change only at nodes