Chapter 26 - Phylogeny and the Tree of Life

Question 1

Phylogeny -

Answer 1

the evolutionary history of a species or group of species

Question 2

Systematics -

Answer 2

a discipline focused on classifying organisms and determining their evolutionary relationships

Question 3

Genus (plural, genera)

Answer 3

the first part of a binomial, containing species that appear to be closely related

Question 4

Specific epithet (species) -

Answer 4

unique for each species within a genus

Question 5

The Linnaean system -

Answer 5

related genera in the same family, families into orders, orders into classes, classes into phyla (phylum), phyla into kingdoms, and, more recently, kingdoms into domains

Question 6

Taxon -

Answer 6

named group at any level of the hierarchy (ex. Panthera is a ____ at the genus level, and Mammalia is a ____ at the class level)

Question 7

Phylogenetic tree -

Answer 7

the evolutionary history of a group of organisms can be represented in a branching diagram

Question 8

a phylogenetic tree represents a ________ about evolutionary relationships

Answer 8

hypothesis

Question 9

Branch point -

Answer 9

represents the common ancestor of the two evolutionary lineages diverging from it

Question 10

An evolutionary lineage -

Answer 10

sequence of ancestral organisms leading to a particular descendant taxon

Question 11

Sister taxa -

Answer 11

groups of organisms that share an immediate common ancestor that is not shared by any other group

Question 12

Basal taxon -

Answer 12

a lineage that diverges from all other members of its group early in the history of the group

Question 13

Rooted -

Answer 13

which means that a branch point within the tree (often drawn farthest to the left) represents the most recent common ancestor of all taxa in the tree

Question 14

Phylogenetic trees:

Answer 14

intend to show patterns of descent, not phenotypic similarity; cannot necessarily show the ages of the taxa or branch points shown in a tree

Question 15

Homologies -

Answer 15

phenotypic and genetic similarities due to shared ancestry are called …

Question 16

Analogy

Answer 16

similarity between organisms that is due to convergent evolution

Question 17

Homology -

Answer 17

similarity between organisms that is due to shared ancestry

Question 18

Convergent evolution -

Answer 18

occurs when similar environmental pressures and natural selection produce similar (analogous) adaptations in organisms from different evolutionary lineages

Question 19

If genes in two organisms share many portions of their nucleotide sequences, it is likely that the genes are __________

Two sequences that resemble each other at many points along their length most likely are __________

Answer 19

homologous; homologous

Question 20

Cladistics -

Answer 20

an approach to systematics where common ancestry is the primary criterion used to classify organisms

Question 21

Clades -

Answer 21

groups where each of which includes an ancestral species and all of its descendants

Question 22

Monophyletic taxon -

Answer 22

consists of an ancestral species and all of its descendants

Question 23

Paraphyletic taxon -

Answer 23

consists of an ancestral species and some, but not all, of its descendants

Question 24

Polyphyletic taxon -

Answer 24

includes distantly related species but does not include their most recent common ancestor

Question 25

Shared ancestral character -

Answer 25

a character that originated in an ancestor of the taxon

Question 26

Shared derived character -

Answer 26

an evolutionary novelty unique to a clade

Question 27

An outgroup -

Answer 27

is a species or group of species from an evolutionary lineage that is closely related to but not part of the group of species that we are studying

Question 28

An ingroup -

Answer 28

the species or group of species from an evolutionary lineage that is being studied

Question 29

By comparing members of the ______ with each other and with the _______, we can determine which characters were derived at the various branch points of vertebrate evolution

Answer 29

ingroup; outgroup

Question 30

Principle of maximum parsimony -

Answer 30

according to _______ we should first investigate the simplest explanation that is consistent with the facts

Question 31

In the case of trees based on morphology, the most parsimonious tree requires the fewest _________ __________.

Answer 31

evolutionary events

Question 32

For phylogenies based on DNA, the most parsimonious tree requires the fewest ______ _______.

Answer 32

base changes

Question 33

Maximum likelihood approach -

Answer 33

identifies the tree most likely to have produced a given set of DNA data based on certain probability rules about how DNA sequences change over time

Question 34

Orthologous genes -

Answer 34

where the homology is the result of a speciation event and hence occurs between genes found in different species

can only diverge after speciation has taken place, that is, after the genes are found in separate gene pools

Question 35

Paralogous genes -

Answer 35

where the homology results from gene duplication; hence, multiple copies of these genes have diverged from one another within a species

can diverge within a species because they are present in more than one copy in the genome

Question 36

Molecular clock -

Answer 36

an approach for measuring the absolute time of evolutionary change based on the observation that some genes and other regions of genomes appear to evolve at constant rates

Question 37

Molecular clock example: the number of nucleotide substitutions in _______ _______ is proportional to the time that has elapsed since the genes branched from their common ancestor.

Answer 37

orthologous genes (ex.)

Question 38

Molecular clock example: the number of substitutions is proportional to the time since the ancestral gene was duplicated in ________ _____

Answer 38

paralogous genes (ex.)

Question 39

Selectively neutral -

Answer 39

neither beneficial nor detrimental

Question 40

Differences in the ______ _____ for different genes are related to how important a gene is

Answer 40

clock rate

Question 41

The five kingdoms: This system highlighted the two fundamentally different types of cells, prokaryotic and eukaryotic, and set the prokaryotes apart from all eukaryotes by placing them in their own kingdom, Monera

Answer 41

Monera (prokaryotes), Protista (a diverse kingdom consisting mostly of unicellular organisms), Plantae, Fungi, and Animalia

Question 42

Domain Bacteria -

Answer 42

contains most of the currently known prokaryotes

Question 43

Monera -

Answer 43

kingdom of prokaryotes

Question 44

Protista -

Answer 44

a diverse kingdom consisting mostly of unicellular organisms

Question 45

Domain Archaea -

Answer 45

consists of a diverse group of prokaryotic organisms

Question 46

Domain Eukarya -

Answer 46

consists of all the organisms that have cells containing true nuclei

Question 47

Horizontal gene transfer -

Answer 47

a process in which genes are transferred from one genome to another through mechanisms such as exchange of transposable elements and plasmids, viral infection, and fusions of organisms