Chapter 22

Question 1

Ancestral Trait

Answer 1

The trait originally present in the ancestor of a given group; may be retained or changed in the descendants of that ancestor.

Question 2

Binomial Nomenclature

Answer 2

A taxonomic naming system in which each species is given two names (a genus name followed by a species name).

Question 3

Clade

Answer 3

A monophyletic group made up of an ancestor and all of its descendants

Question 4

Convergent Evolution

Answer 4

Independent evolution of similar features from different ancestral traits.

Question 5

Derived Trait

Answer 5

A trait that differs from the ancestral trait. (Contrast with shared derived trait.)

Question 6

Evolutionary Reversal

Answer 6

The reappearance of an ancestral trait in a group that had previously acquired a derived trait.

Question 7

Genus

Answer 7

A group of related, similar species recognised by taxonomists with a distinct name used in binomial nomenclature.

Question 8

Homolog

Answer 8

(1) In cytogenetics, one of a pair (or larger set) of chromosomes having the same overall genetic composition and sequence. In diploid organisms, each chromosome inherited from one parent is matched by an identical (except for mutational changes) chromosome—its homolog—from the other parent. (2) In evolutionary biology, one of two or more features in different species that are similar by reason of descent from a common ancestor.

Question 9

Homoplasy

Answer 9

The presence in multiple groups of a trait that is not inherited from the common ancestor of those groups. Can result from convergent evolution, evolutionary reversal, or parallel evolution.

Question 10

Ingroup

Answer 10

In a phylogenetic study, the group of organisms of primary interest. (Contrast with outgroup.)

Question 11

Maximum Likelihood

Answer 11

A statistical method of determining which of two or more hypotheses (such as phylogenetic trees) best fit the observed data, given an explicit model of how the data were generated.

Question 12

Molecular Clock

Answer 12

The approximately constant rate of divergence of macromolecules from one another over evolutionary time; used to date past events in evolutionary history.
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Question 13

Monophyyletic

Answer 13

Pertaining to a group that consists of an ancestor and all of its descendants. (Contrast with paraphyletic, polyphyletic.)

Question 14

Outgroup

Answer 14

In phylogenetics, a group of organisms used as a point of reference for comparison with the groups of primary interest (the ingroup).

Question 15

Paraphyletic

Answer 15

ertaining to a group that consists of an ancestor and some, but not all, of its descendants. (Contrast with monophyletic, polyphyletic.)

Question 16

Parsimony

Answer 16

Preferring the simplest among a set of plausible explanations of any phenomenon.

Question 17

Phylogenetic Tree

Answer 17

A graphic representation of lines of descent among organisms or their genes.

Question 18

Phylogeny

Answer 18

The evolutionary history of a particular group of organisms or their genes.

Question 19

Polyphyletic

Answer 19

Pertaining to a group that consists of multiple distantly related organisms, and does not include the common ancestor of the group. (Contrast with monophyletic, paraphyletic.)

Question 20

Sister Group

Answer 20

Two phylogenetic groups that are each other’s closest relatives.

Question 21

Synapomorphy

Answer 21

A trait that arose in the ancestor of a phylogenetic group and is present (sometimes in modified form) in all of its members, thus helping to delimit and identify that group. Also called a shared derived trait.

Question 22

Systematics

Answer 22

The scientific study of the diversity and relationships among organisms.