Cladistics and Phylogenetics

Question 1

Evolution

Answer 1

According to Darwin, evolution is descent with modification

Question 2

Phylogenetic tree

Answer 2

Depicts hypothetical phylogeny of the taxa under consideration

Question 3

Node (on phylogenetic tree)

Answer 3

Represents a speciation event

Question 4

Internode (on phylogenetic tree)

Answer 4

Line connecting two speciation events and representing 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 alternative 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 a hierarchical system that ideally reflects evolutionary history

Question 7

Phylogeny

Answer 7

The evolutionary relationships among organisms

Question 8

Systematics

Answer 8

Field of biology that deals with the diversity of life. Consists of the areas of phylogenetics and taxonomy

Question 9

Taxon (plural taxa)

Answer 9

Any named group of organisms that is not necessarily a clade

Question 10

Taxonomy

Answer 10

The science of naming and classifying organisms

Question 11

Phylogenetics

Answer 11

The field of biology that deals with the relationships between organisms, the discovery of these relationships, and the study of the causes behind these relationships

Question 12

Cladistics

Answer 12

Organisms grouped strictly on homology. Trees are based on genealogy and not just similarity.

Question 13

Apomorphy

Answer 13

A derived character

Question 14

Synapomorphy

Answer 14

A shared derived characteristic used to infer ancestry and thus construct clades

Question 15

Autapomorphy

Answer 15

A unique derived characteristic not shared with any other taxon

Question 16

Plesiomorphy

Answer 16

An ancestral character state for the taxa under consideration

Question 17

Symplesiomorphy

Answer 17

An ancestral character shared by the taxa under consideration

Question 18

Character state

Answer 18

Describes a character in terms of its state, e.g. hair present

Question 19

Character

Answer 19

A heritable trait

Question 20

Polarity of characters

Answer 20

The states of characters used in a cladistic analysis, whether ancestral or derived

Question 21

Analog

Answer 21

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

Question 22

Homoplasy

Answer 22

A character shared by a set of species but NOT present in the common ancestor

Question 23

Homolog

Answer 23

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

Question 24

Homology

Answer 24

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

Question 25

Clade

Answer 25

A monophyletic taxon – a group of organisms that includes the most recent common ancestor of all its members and all of the descendents of that most recent common ancestor

Question 26

Cladogenesis

Answer 26

The development of a new clade; speciation

Question 27

Cladogram

Answer 27

A diagram that depicts hypothetical lineages leading to the taxa under consideration

Question 28

Convergent evolution

Answer 28

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

Question 29

Hypothesis

Answer 29

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

Question 30

Ingroup

Answer 30

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

Question 31

Outgroup

Answer 31

In 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 32

Lineage

Answer 32

Any continuous line of descent

Question 33

Monophyletic

Answer 33

Term applied to a group of organisms which includes the most recent common ancestor and all of its descendants. Also known as a clade.

Question 34

Paraphyletic

Answer 34

Term applied to a group of organisms which includes the most recent common ancestor but NOT ALL of the descendants

Question 35

Polyphyletic

Answer 35

Term applied to a group of organisms which does NOT include the most recent common ancestor

Question 36

Sister group

Answer 36

The two clades resulting from the splitting of a single lineage

Question 37

Parsimony

Answer 37

A rule used to choose among possible cladograms – the cladogram that implies the least number of changes in character states is the best cladogram