Lecture #5: Phylogeny Recap and Practice

Question 1

LO #1: Explain the fundamental features of phylogenetic trees

Answer 1

phylogenetic tree is meant to reflect the pattern of successive speciation events that lead to more complex relationships

Question 2

LO #2: 1. Interpret patterns of relatedness on phylogenies, including 2. monophyletic, 3. paraphyletic, and 4. polyphyletic groups

Answer 2

1: It is assessed by examining patterns of common ancestry on a tree –> paying close attention to the nodes
2. monophyletic: a group of organisms consisting of the MRCA and all of its descendants
3. paraphyletic: includes MRCA but excludes 1(+) descendants
4. polyphyletic: combines organisms that lack a MRCA

Question 3

LO #3.1: Distinguish b/w homology from homoplasy

Answer 3

homology: is similarity due to common ancestor
homoplasy: similarity due to convergent evolution

Question 4

LO #3.2: explain the relationship b/w homology and synapomorphy

Answer 4

all homologous characters are synapomorphies

ex: wings are synapomorphies of birds (unique to them)

Question 5

LO #4.1: list the essential steps involved in building phylogenetic trees

Answer 5

1. select taxa (ingroups) and outgroups
2. data matrix
3. parsimony and statistical methods

Question 6

LO #4.2: Explain why using unrooted trees is important

Answer 6

using unrooted trees is important b/c the math is much better for a more realistic tree

Question 7

LO #5: Show how uncertainty is reflected on phylogenetic trees

Answer 7

use of a polytomy

Question 8

LO #6: Provide the uses of phylogenetic trees in biology

Answer 8

1. conservation biology: giraffes

2. medical forensics: HIV dentist