Lecture #2: Phylogeny Concepts I Flashcards
LO #1: identify three ways in which phylogenies are simplifications of evolutionary history
- populations w/in species are usually not shown
- simplification of complex population-level processes that extend back in time
- many branches may not be shown
LO #2: Recognize that nodes are free to rotate on phylogenetic trees w/out affecting relationships
relations on trees are unaffected by the rotation of nodes (such as A and B is the same as B and A)
LO #3: evaluate relationships on contrasting phylogenies
this is all about when you change HOW the tree looks like: ABCD, C is D’s sister taxon. But if you change it to ACBD, then B becomes D’s sister taxon.
LO #4: Distinguish 1. monophyly, 2. paraphyly, and 3. polyphyly
- natural group (all) (triangle test)
- artificial group (bad) (excludes some)
- artificial group (evil) (no MRCA)
LO #5: Interpret patterns of relatedness on phylogenetic trees
It is assessed by examining patterns of common ancestry on a tree –> paying close attention to the nodes
a group of organisms consisting of their MRCA and all of its descendants (includes the root node)
monophyletic group (monophyly)
excludes descendants of a MRCA or combines organisms that lack a MRCA
non-monophyletic groups
includes the MRCA. but excludes one or more descendants (common)
paraphyletic group
combine organisms that lack a MRCA
polyphyletic group
on 1. _____ phylogenies 2. ________ and 3. ________ blend together
- small
- paraphyly
- polyphyly
when 1. ____ phylogenies 2. _____ have enough taxa, it can start looking like a 3. _________
- small
- don’t
- paraphyly
example of:
- A’s closest relative to B
- C’s closest relative to D
- Closest relative to C and D
sister taxa
two descendants splitting from the same node
sister taxa
