Phylogeny

Question 1

phylogenetic tree

Answer 1

model of how a group of organisms descended from a common ancestor

Question 2

Branch

Answer 2

represents a species

Question 3

Node

Answer 3

Where a branch diverges into two or more sub-branches.

-where groups split

Question 4

Polytomy

Answer 4

multiple species appear to diverge at one node

-point where more than 2 branches diverge

Question 5

Sister taxa

Answer 5

2 taxa that share a common node

Question 6

Synapomorphy

Answer 6

trait shared by two or more species inherited from common ancestor
-shared, derived characters (evidence 2 taxa related)

Question 7

Out-group

Answer 7

represents a taxon that diverged earlier from the other taxa in the tree; useful in determining the root of the tree.

Question 8

monophyletic group

Answer 8

group defined by a single common ancestor

Question 9

Phenetic

Answer 9

use measures of distance between organisms

- ignores the phylogenetic model of organisms evolving from each other while inferring phylogenies

Question 10

Cladistic

Answer 10

based on modeling how evolution occurs on the tree

- makes use of the phylogenetic model of organisms evolving from each other to infer phylogenies

Question 11

basal or ancestral characters

Answer 11

characteristics of the common ancestor

Question 12

root

Answer 12

beginning of the tree is where the outgroup branches from the group

Question 13

convergent evolution

Answer 13

Two species may have the same trait because the trait evolved twice independently

Question 14

secondary loss

Answer 14

An organism may lack a character that its ancestors had

Question 15

homoplasies

Answer 15

Similarities that are not homologies (not due to common ancestor)

Question 16

parsimony

Answer 16

with the fewest number of changes necessary (when creating tree)

Question 17

Derived character

Answer 17

Character not shared by common ancestor of the group

Question 18

Bacteria

Answer 18

• no nuclei
• mostly small
• most of the micro-organisms you see

Question 19

Archaea

Answer 19

• no nuclei
• mostly small
• rarer
• live in more extreme environments

Question 20

Eukarya

Answer 20

large, nucleated cells

Question 21

Eukaryotes

Answer 21

• sisters with archaea

- Characterized by nuclei and mitochondria

Question 22

Reuniting can create new species

Answer 22

– Hybridization

– Allopolyploidy

Question 23

Allopolyploidy

Answer 23

polyploids arising from different species

Question 24

Habitat bias

Answer 24

Things that live in swampy areas, or underground

Question 25

Taxonomic bias

Answer 25

Hard things, or hard parts of things

Question 26

Temporal bias

Answer 26

Things that lived more recently have had less time to be destroyed, or to be buried too deep for recovery

Question 27

Abundance bias

Answer 27

Things that are more abundant have more chances to be preserved

Question 28

radiation events

Answer 28

Diversity sometimes arises gradually, and sometimes dramatically

Question 29

mass extinction events

Answer 29

Species (and families, and bigger groups) sometimes disappear gradually, and some- times dramatically

Question 30

adaptive radiation

Answer 30

occurs when a single lineage produces many descendant species, in a short period of time, that make their living in a variety of different ways
- Triggered by opportunity, either in the environment, or because of the evolution of the organisms themselves

Question 31

Ecological opportunity

Answer 31

• An organism arrives in an area with no similar organisms

- A group of competing species is driven extinct (or nearly extinct) by some other cause

Question 32

Morphological innovation

Answer 32

an organism comes up with a good, new idea

Question 33

Co-evolution

Answer 33

evolution of one group creates new niches for another group, and vice versa

Question 34

Hox gene

Answer 34

Hox gene mutations allowed early animals to develop complex body plans

• involved in determining the identity of different body parts
• Taxa with simpler body structures tend to have fewer hox genes
• Evidence that new hox genes were largely created by gene duplication events

Question 35

Gene duplication

Answer 35

One or more genes may be accidentally duplicated so that the genome has two copies of each gene

• This may make the organism less efficient, and thus be selected against
• may allow for innovation

Question 36

Tips

Answer 36

represents observed taxa which are the endpoints of the process trying to be modelled

Question 37

Cladistic vs Phenetic

Answer 37

Cladistic is better

-use phenetic when: only data is distances or dont have enough baseline info

Question 38

Genetic vs Morphological

Answer 38

Genetic-usually have more info and info easier to measure precisely
-use morph. whe genetic info unavailable

Question 39

Limitations to phylogenetic tree

Answer 39

• cannot summarize true history of life
• trees constructed by humans not best approx
• our guesses change over time

Question 40

Intact fossils

Answer 40

retain form

Question 41

compression fossil

Answer 41

squashed into thin film

Question 42

cast fossils

Answer 42

occur when decomposing piece replaced by mineral different from surrounding

Question 43

Permineralized fossil

Answer 43

occur if minerals infiltrate cells as decomposing