Unit #1

Question 1

evolution

Answer 1

descent with modification

Question 2

phylogenetic tree

Answer 2

A diagram that depicts the hypothetical phylogeny of the taxa under consideration.
The points at which lineages split represent ancestor taxa to the descendant taxa appearing at the
terminal points of the cladogram

Question 3

node

Answer 3

represents a speciation event on the phylogenetic tree

Question 4

internode

Answer 4

a line on phylogenetic tree connecting two speciation events and represents at least one
ancestral species.

Question 5

Selection

Answer 5

Process which favors one feature of organisms in a population over another feature found in
the population. This occurs through differential reproduction - those with the favored feature produce
more offspring than those with the other feature, such that they become a greater percentage of the
population in the next generation.

Question 6

Biological classification

Answer 6

The orderly arrangement of organisms in hierarchical system that ideally
reflects evolutionary history

Question 7

Phylogeny

Answer 7

The evolutionary relationships among organisms; the patterns of lineage branching
produced by the true evolutionary history of the organisms being considered.

Question 8

Systematics

Answer 8

Field of biology that deals with the diversity of life. Systematics is usually divided into the
two areas of phylogenetics and taxonomy

Question 9

Taxon

Answer 9

Any named group of organisms, not necessarily a clade.

Question 10

Taxonomy

Answer 10

The science of naming and classifying organisms.

Question 11

Phylogenetics

Answer 11

Field of biology that deals with the relationships between organisms. It includes the
discovery of these relationships, and the study of the causes behind this pattern.

Question 12

Clasdistics

Answer 12

organisms grouped strictly on homology. Trees are based on genealogy not simply similarity.

Question 13

Ancestor

Answer 13

Any organism, population, or species from which some other organism, population, or species
is descended by reproduction

Question 14

Character

Answer 14

Heritable trait possessed by an organism

Question 15

Apomorphy

Answer 15

a derived character

Question 16

Synapomorphy

Answer 16

a shared derived characteristic; used to infer ancestry and thus construct clades

Question 17

Autapomorphy

Answer 17

a unique derived characteristic (not shared with any other taxon)

Question 18

Plesiomorphy

Answer 18

an ancestral character state for the taxa under consideration

Question 19

Symplesiomorphy

Answer 19

A ancestral character shared by the taxa under consideration

Question 20

Character state

Answer 20

characters are usually described in terms of their states, for example: “hair present” vs.
“hair absent,” where “hair” is the character, and “present” and “absent” are its states

Question 21

Ancestral

Answer 21

Describes a character state that is present in the common ancestor of a clade. An ancestral
character state is inferred to be the original condition of that character within the clade under
consideration.

Question 22

Derived

Answer 22

Describes a character state that is present in one or more subclades, but not all, of a clade
under consideration. A derived character state is inferred to be a modified version of the primitive
condition of that character, and to have arisen later in the evolution of the clade. For example,
“presence of hair” is a primitive character state for all mammals, whereas the “hairlessness” of whales
is a derived state for one subclade within the Mammalia

Question 23

Polarity of characters

Answer 23

The states of characters used in a cladistic analysis, either ancestral or derived.
Ancestral characters are those acquired by an ancestor deeper in the phylogeny than the most recent
common ancestor of the taxa under consideration. Derived characters are those acquired by the most
recent common ancestor of the taxa under consideration

Question 24

Analog

Answer 24

A feature that appears similar in two taxa which have originated from two different ancestors.

Question 25

Homoplasy

Answer 25

a character shared by a set of species but not present in their common ancestor

Question 26

Homolog

Answer 26

A feature that appears similar in two or more taxa with a common ancestor that also
possessed that feature.

Question 27

Homology

Answer 27

Two structures are considered homologous when they are inherited from a common
ancestor, which possessed the structure

Question 28

Clade

Answer 28

A monophyletic taxon; a group of organisms which includes the most recent common ancestor of
all of its members and all of the descendants of that most recent common ancestor.

Question 29

Cladogenesis

Answer 29

The development of a new clade; the splitting of a single lineage into two distinct
lineages; speciation.

Question 30

Cladogram

Answer 30

A diagram, resulting from a cladistic analysis, which depicts a hypothetical branching
sequence of lineages leading to the taxa under consideration. The points of branching within a
cladogram are called nodes. All taxa occur at the endpoints of the cladogram.

Question 31

Convergent evolution

Answer 31

an evolutionary change producing similar characteristics in two or more distantly
related forms because of their separate adaptation to common ecological conditions

Question 32

Hypothesis

Answer 32

A concept or idea that can be falsified by various scientific methods.

Question 33

Ingroup

Answer 33

In a cladistic analysis, the set of taxa which are hypothesized to be more closely related to
each other than any are to the outgroup.

Question 34

Outgroup

Answer 34

• In a cladistic analysis, any taxon used to help resolve the polarity of characters, and which is
  hypothesized to be less closely related to each of the taxa under consideration than any are to each
  other.

Question 35

Lineage

Answer 35

Any continuous line of descent; any series of organisms connected by reproduction by parent
of offspring

Question 36

Monophyletic

Answer 36

Term applied to a group of organisms, which includes the most recent common ancestor
of all of its members and all of the descendants of that most recent common ancestor. A monophyletic
group is called a clade.

Question 37

Paraphyletic

Answer 37

Term applied to a group of organisms, which includes the most recent common ancestor
of all of its members, but not all of the descendants of that most recent common ancestor.

Question 38

Polyphyletic

Answer 38

Term applied to a group of organisms, which does not include the most recent common
ancestor of those organisms; the ancestor does not possess the character shared by members of the
group

Question 39

Sister group

Answer 39

The two clades resulting from the splitting of a single lineage.

Question 40

Parsimony

Answer 40

Refers to a rule used to choose among possible cladograms, which states that the cladogram implying the least number of changes in character states is the best.