Chapter 26

Question 1

the evolutionary history of a species or group of related species.

Answer 1

phylogeny

Question 2

a scientific discipline focused on classifying organisms and determining their evolutionary relationships.

Answer 2

systematics

Question 3

a scientific discipline concerned with naming and classifying the diverse forms of life.

Answer 3

taxonomy

Question 4

the two-part latinized name of a species, consisting of the genus and specific epithet.

Answer 4

binomial

Question 5

a branching diagram that represents a hypothesis about the evolutionary history of a group of organisms.

Answer 5

phylogenetic tree

Question 6

the representation on a phylogenetic tree of the divergence of two or more taxa from a common ancestor. Most ____ _____ are shown as dichotomies, in which a branch representing the ancestral lineage splits (at the _____ _____) into two branches, one for each of the two descendant taxa.

Answer 6

branch points

Question 7

system of classification of organisms based on evolutionary relationships. Only groups that include a common ancestor and all of its descendants are named.

Answer 7

PhyloCode

Question 8

groups of organisms that share an immediate common ancestor and hence each other’s closest relatives.

Answer 8

sister taxa

Question 9

in a phylogenetic tree, a branch point from which more than two descendant taxa emerge. A ______ indicates that the evolutionary relationships among the descendant taxa are not yet clear.

Answer 9

polytomy

Question 10

similarity between two species that is due to convergent evolution rather than to descent from a common ancestor with the same trait.

Answer 10

analogy

Question 11

similar (analogous) structure or molecular sequence that has evolved independently in two species.

Answer 11

homoplasy

Question 12

a scientific discipline that uses nucleic acids or other molecules in different species to infer evolutionary relationships.

Answer 12

molecular systematics

Question 13

an approach to systematics in which organisms are placed into groups called clades based primarily on common descent.

Answer 13

cladistics

Question 14

A group of species that includes an ancestral species and all its descendants.

Answer 14

clades

Question 15

Pertaining to a group of taxa that consists of a common ancestor and all its descendants. A _____ taxon is equivalent to a clade.

Answer 15

monophyletic

Question 16

pertaining to a group of taxa that consists of a common ancestor and some, but not all, of its descendants.

Answer 16

paraphyletic

Question 17

a character, shared by members of a particular clade, that originated in an ancestor that is not a member of that clade.

Answer 17

shared ancestral character

Question 18

an evolutionary novelty that is unique to a particular clade.

Answer 18

shared derived character

Question 19

a species or group of species from an evolutionary lineage that is known to have diverged before the lineage that contains the group of species being studied. A(n) _______ is selected so that its members are closely related to the group of species being studied, but not as closely related as any study-group members are to each other.

Answer 19

outgroup

Question 20

a species or group of species whose evolutionary relationships we seek to determine.

Answer 20

ingroup

Question 21

a principle that states that when considering multiple explanations for an observation, one should first investigate the simplest explanation that is consistent with the facts.

Answer 21

maximum parsimony

Question 22

as applied to systematics, a principle that states that when considering multiple phylogenetic hypotheses, one should take into account the hypothesis that reflects the most likely sequence of evolutionary events, given certain rules about how DNA changes over time.

Answer 22

maximum likelihood

Question 23

an approach in which features shared by two groups of organisms are predicted (by parsimony) to be present in their common ancestor and all of its descendants.

Answer 23

phylogenetic bracketing

Question 24

homologous genes that are found in different species because of speciation.

Answer 24

orthologous genes

Question 25

homologous genes that are found in the same genome as a result of gene duplication.

Answer 25

paralogous genes

Question 26

a method for estimating the time required for a given amount of evolutionary change, based on the observation that some regions of genomes appear to evolve at constant rates.

Answer 26

molecular clock

Question 27

the hypothesis that much evolutionary change in genes and proteins has no effect on fitness and therefore is not influenced by Darwinian natural selection.

Answer 27

neutral theory

Question 28

the transfer of genes from one genome to another through mechanisms such as transposable elements, plasmid exchange, viral activity, and perhaps fusions of different organisms.

Answer 28

horizontal gene transfer