#bio 

**Synapomorphy**: a characteristic present in an ancestral species and shared exclusively (in more or less modified form) by its evolutionary descendants. **Homology:** similarity due to common ancestry **Analogy:** similarity of function and superficial resemblance of structures that are not due to common ancestry **Most Recent Common Ancestor:** This is represented by a node on an evolutionary tree. It represents the last time groups were members of the same population. **Monophyletic Group:** A grouping that includes all the descendant taxa from their most recent common ancestor. **Paraphyletic Group:** A grouping that excludes one or more descendants from the grouping based on their most recent common ancestor. **Polyphyletic Group:** A grouping (typically based on analogy) that does not have an immediate common ancestor