Theme 5A/B: Evolutionary patterns Flashcards
1
Q
What’s an extant species?
A
- A living species
2
Q
What’s a phylogenetic tree?
A
- A branching diagram that shows the relationships between species, often according to the time since a common ancestor
- Acts as a hypothesis for evolutionary relationships
3
Q
What’s the difference between a phylogram and a cladogram?
A
- Phylogram - a tree where the branch lengths represent the amount of inferred evolutionary change/time
- Cladogram - a tree where all branches are of equal length
4
Q
What’s a sister group?
A
- Two species that share a unique common ancestor not shared by any other species or group
5
Q
What’s the difference between a character and its character states?
A
- A character describes a specific trait, while a character state describes the variation within that trait.
- Ex. A character being a flower, while the character states including blue flowers or yellow flowers
6
Q
What are homologous characters?
A
- Characteristics that are shared because of common ancestry
- Ex. the four limbs of tetrapods
7
Q
What are analogous characters?
A
- Similarity in appearance but not in origin
- Shared because of convergent evolution
8
Q
What are synapomorphies?
A
- Homologies shared by some, but not all species. Help build phylogenetic trees
9
Q
What does the principle of parsimony describe?
A
- The phylogeny requiring the fewest evolutionary changes is the best estimate of the true phylogeny (most parsimonious)
10
Q
What are the different kinds of phylogenetic groups?
A
- Monophyletic - includes a CA and all of its descendants
- Paraphyletic - includes a CA and some, but not all of its descendants
- Polyphyletic - Does not include the CA
11
Q
What’s the difference between anagenesis and cladogenesis?
A
- Anagenesis - speciation where the ancestor species is wholly replaced by new species
- Cladogenesis - Parent species splits into two new species
12
Q
What’s the difference between graduated evolution and punctuated evolution?
A
- Graduated - Slow and steady gradual evolution
- Punctuated - Rare and rapid events of branching speciation
*seems to be a combination of the two
*fossil record shows the idea of punctuated evolution