Introduction

https://www.lesswrong.com/posts/fRwdkop6tyhi3d22L/there-s-no-such-thing-as-a-tree-phylogenetically

This is a linkpost for https://eukaryotewritesblog.com/2021/05/02/theres-no-such-thing-as-a-tree/

[Crossposted from Eukaryote Writes Blog.]

So you’ve heard about how fish aren’t a monophyletic group? You’ve heard about carcinization, the process by which ocean arthropods convergently evolve into crabs? You say you get it now? Sit down. Sit down. Shut up. Listen. You don’t know nothing yet.

“Trees” are not a coherent phylogenetic category. On the evolutionary tree of plants, trees are regularly interspersed with things that are absolutely, 100% not trees. This means that, for instance, either:

• The common ancestor of a maple and a mulberry tree was not a tree.
• The common ancestor of a stinging nettle and a strawberry plant was a tree.
• And this is true for most trees or non-trees that you can think of.

I thought I had a pretty good guess at this, but the situation is far worse than I could have imagined.