Chapter 4 : Phylogeny And Evolutionary History

Question 1

Who developed the taxonomic system?

Answer 1

Carolus Linnaeus

Question 2

Phylogenetic Systematics

Answer 2

Classifying organisms according to their evolutionary histories.

Question 3

Phylogeny

Answer 3

The branching relationships of populations as they give rise to multiple descendant populations over evolutionary time.

Question 4

What does the study of phylogeny allow?

Answer 4

It allows us to reconstruct the tree of life and understand major events in evolutionary history.

Question 5

Characters

Answer 5

Observable characteristics of organisms; anatomical features or behavioral patterns.

Question 6

Traits

Answer 6

Specific values of a character; tall or short.

Question 7

What type of characters are most commonly used today?

Answer 7

DNA sequences

Question 8

What is the difference between a pedigree and a phylogeny?

Answer 8

Pedigree: ancestry of individuals.
- nodes = individuals

Phylogeny: ancestry of populations.
- nodes = populations

Question 9

Who established the modern approach to classification?

Answer 9

Willi Hennig

Question 10

Tree of life

Answer 10

Historical relationships that connect all living things

Question 11

What are some examples of character?

Answer 11

Anatomical features, developmental or embryological processes, behavioral patterns, genetic sequences

Question 12

What do phylogenies tell us?

Answer 12

The ancestry of a population

Question 13

What do nodes in a phylogeny represent?

Answer 13

Populations

Question 14

What is a phylogenetic tree a hypothesis about?

Answer 14

Evolutionary relationships

Question 15

What is the location and order of phylogenetic tree hypothetically?

Answer 15

The way that evolutionary history has unfolded

Question 16

Taxon

Answer 16

A branch tip that represents a group of related organisms

Question 17

Nodes

Answer 17

The branch points where the tree splits

Question 18

What do nodes represent?

Answer 18

Recent common ancestors to the species that come after splitting or branching point

Question 19

Root

Answer 19

The common ancestors to all the species on the tree

Question 20

Sister taxa

Answer 20

Taxa derived from the same node

Question 21

Polytomy

Answer 21

A node with more than two branches arising from it

Question 22

Monophyletic Group

Answer 22

A taxonomic group consisting of all descendants of the group’s most common ancestor and no other members

Question 23

Clade

Answer 23

A group of species that share a single recent common ancestor

Question 24

Polyphyletic Group

Answer 24

Do not represent proper evolutionary clades and no longer used in modern systematics

Question 25

Paraphyletic Group

Answer 25

Contains the group's most common ancestor but not all of its descendants

Question 26

Rooted trees

Answer 26

Shows the common lineage from which all the species on the tree are derived is indicated at the base of the tree

Question 27

What does direction in a rooted tree indicate?

Answer 27

Passage of time

Question 28

Unrooted tree

Answer 28

Do not fully indicate the direction of time

Question 29

What does a phylogram indicate?

Answer 29

Evolutionary relationships and the amount of sequence change along each branch by means differing horizontal branch lengths

Question 30

Cladogram

Answer 30

Trees that do not have different branch lengths, the branch tips are aligned

Question 31

Phylogram

Answer 31

Trees that represent evolutionary change with branch lengths

Question 32

Chronograms

Answer 32

Trees that show branch lengths that represent actual time rather than the amount of evolutionary time

Question 33

What does the study of phylogeny rely on?

Answer 33

Our observations of traits displayed by organisms

Question 34

What is a homologous trait?

Answer 34

A trait that is found in two or more species because those species have a common ancestor

Question 35

What is an analogous trait?

Answer 35

A trait that is shared by two or more species because the traits have risen independently in each species not because of a history of common descent

Question 36

What are synamorphies?

Answer 36

Shared derived traits

Question 37

What do evolutionary biologists use synamorphies for?

Answer 37

To infer the structure of phylogenetic trees

Question 38

Soft polytomy

Answer 38

Result of insufficient phylogenetic information

Question 39

Hard polytomy

Answer 39

Arises when three or more sampled genes trace their ancestry to a single gene in an ancestral organism

Question 40

What is a node?

Answer 40

The point where a phylogenetic tree branches

Question 41

What is a monophyletic group / clade?

Answer 41

A taxonomic group that consists of a unique common ancestor and each and every one of its descendant species

Question 42

What does a clade always consist of?

Answer 42

A group of species that share a single common ancestor

Question 43

What is a paraphyletic group?

Answer 43

A group that includes the common ancestor of all its members but does not contain each and every species that descended from that ancestor

Question 44

What do the branch lengths represent in phylograms?

Answer 44

Evolutionary change

Question 45

What are vestigial traits?

Answer 45

Those that have no current functionbut appear to have been important in the evolutionary past

Question 46

Outgroup

Answer 46

A group with a known evolutionary relationship to the taxon we are studying

Question 47

Synapomorphy

Answer 47

A derived trait that is shared in two populations because it was inherited from a recent common ancestor

Question 48

Homoplasy

Answer 48

A trait that is similar in two species because of a convergent evolution rather than common ancestry

Question 49

Symplesiomorphy

Answer 49

A derived trait that has arisen so recently that it appears in only one of two sister taxa

Question 50

Convergent evolution

Answer 50

When two or more populations or species become more similar to one another because they are exposed to similar selective conditions and leads to analogous traits

Question 51

Divergent evolution

Answer 51

When closely related populations or closely related species diverge from one another because natural selection operates differently on each of them

Question 52

What does the presence of analogous traits reveal?

Answer 52

Natural selection generates structurally or functionally similar solutions to similar problems