L48 Anthro 150A Lecture Notes - Lecture 6: Most Recent Common Ancestor, Weight-Bearing, Paraphyly
Document Summary
2 different ways to visually depict phylogeny: Provides direct information about ancestry and descent. No direct information about ancestry and descent. It is a branching diagram illustrating recency of common ancestry. Has nodes that represent a hypothetical ancestor (that we might not have any evidence for) that gave rise to both branching species. There is a last common ancestor at each node. Clade: a group that includes all of the descendants of a single last common ancestor. A clade is a natural group - we group them together naturally because they have a common ancestry. Paraphyletic group: a group that does not include all of the descendents of a single last common ancestor. The last common ancestor shows where that certain trait evolved: Lca of vertebrates is where a bondy skull & vertebrae evolved. Lca of tetrapods is where 4 weight bearing limbs evolved. Lca of amniotes is where water tight membranes around the embryo evolved.
