I was a molecular biology major a while ago, but I never think I really understood cladistics TBH. Now reading about paraphyly, it shows this:
In this phylogenetic tree [second image], the green group is paraphyletic; it is composed of a common ancestor (the lowest green vertical stem) and some of its descendants, but it excludes the blue group (a monophyletic group) which diverged from the green group.
Looking at the "simiiformes", I can understand why you would call that "monophyly", because everything is connected to a common ancestor. But why not just make the blue area a full blue triangle to make the prosimii and simiiformes one triangle/group? In the end, we all share the same ancestor, so I don't see why they are disconnected.
TBH I'm not sure how to read this at all, and am not following the Wiki description. Can you explain how the 3 terms work for a child or layperson with a better concrete example?
We are all composed of atoms, so we are all made of matter. Matter is made of particles, so we are all made of particles. But light is a particle and we are not made of light, even though in some way "we share the same common ancestor" of the quantum field. But light is still called a particle, so the triangle is the group of all particles. I'm not sure I'm getting on the right track.
A paraphyletic group is a monophyletic group from which one or more subsidiary clades (monophyletic groups) are excluded to form a separate group.
Why would they do that?