Evolutionary trees Flashcards
1
Q
Autapomorphy
A
unique character found in a single group
2
Q
Plesiomorphy
A
-primitive character shared by two or more species
3
Q
Synapomorphy
-cladistics groups organisms by synapomorphy
A
shared derived character
-evidence of a relationship
4
Q
what evidence can we infer from phylogeny?
A
- different genes for the same species usually give the same tree (congruence)
- compared inferred tree to “known” phylogeny
5
Q
How do we reconstruct ancestors?
A
- Given a phylogeny we can try and reconstruct what the ancestors looked like
- We can use these reconstructions to test evolutionary scenarios
6
Q
Dollo parsimony
A
-once lost, complex structures are never regained
7
Q
Origin of swords in swordtail fishes:
the “pre-existing bias hypothesis”
A
females evolve a sensory bias
- Female choose males based on sword length.
- Experiments on X. helleri show females prefer males with longer swords.
- Females of swordless species (platys) prefer males with swords.
- Experiments on X. maculatus confirm this.
- Absence of swords must be primitive, so that female’s bias for swords predates the evolution of swords.
8
Q
sister groups
A
-must be same age
