Chapter 24 The Origin of Species

Question 1

Speciation

Answer 1

The process by which one species splits into two or more species.

Question 2

Microevolution

Answer 2

Evolutionary change below the species level; change in the allele frequencies in a population over generations.

Question 3

Macroevolution

Answer 3

Evolutionary change above the species level. Examples: the origin of a new group of organisms through a series of speciation events and the impacts of mass extinctions on the diversity of life and its subsequent recovery.

Question 4

Biological Species Concept

Answer 4

Definition of a species as a group of populations whose members have the potential to interbreed in nature and produce viable, fertile offspring, but do not produce viable, fertile offspring with members of other such groups.

Question 5

Species

Answer 5

A population or group of populations whose members have the potential to interbreed in nature and produce viable, fertile offspring with members of other such groups.

Question 6

Reproductive Isolation

Answer 6

The existence of biological factors (barriers) that impede members of two species from producing viable, fertile offspring.

Question 7

Hybrid

Answer 7

Offspring that results from the mating of individuals from two different species or from two true-breeding varieties of the same species.

Question 8

Prezygotic barrier

Answer 8

A reproductive barrier that impedes mating between species or hinders fertilization if interspecific mating is attempted.

Question 9

Postzygotic Barrier

Answer 9

A reproductive barrier that prevents hybrid zygotes produced by two different species from developing into viable, fertile adults.

Question 10

Morphological Species Concept

Answer 10

A definition of species in terms of measurable anatomical criteria.

Question 11

Ecological Species Concept

Answer 11

A definition of species in terms of ecological niche, the sum of how members of the species interact with the nonliving and living parts of their environment.

Question 12

Phylogenetic Species Concept

Answer 12

A definition of species as the smallest group of individuals that share a common ancestor, forming one branch on the tree of life.

Question 13

Allopatric Speciation

Answer 13

The formation of new species in populations that are geographically isolated from one another.

Question 14

Sympatric Speciation

Answer 14

The formation of new species in populations that live in the same geographic area.

Question 15

Polyploidy

Answer 15

A chromosomal alteration in which the organism possesses more than two complete chromosome sets. It is the result of an accident of cell division.

Question 16

Autopolyploid

Answer 16

An individual that has more than two chromosome sets that are all derived from a single species.

Question 17

Tetraploid

Answer 17

Can produce fertile tetraploid offspring by self-pollinating or by mating with other tetraploids.

Question 18

allopolyploid

Answer 18

A fertile individual that has more than two chromosome sets as a result of two different species interbreeding and combining their chromosomes. They represent a new biological species.

Question 19

Habitat Differentiation

Answer 19

Sympatic speciation can occur when genetic factors enable a subpopulation to exploit a habitat or resource not used by the parent population.

Question 20

Sexual Selection

Answer 20

Sympatic speciation can be driven by sexual selection. ex. females select males based on appearance.

Question 21

Hybrid Zone

Answer 21

A geographic region in which members of different species meet and make, producing at least some offspring of mixed ancestry.

Question 22

Three Outcomes for Hybrid Zone

Answer 22

Reinforcement of barriers, fusion of species, or stability.

Question 23

Reinforcement

Answer 23

In evolutionary biology, a process in which natural selection strengthens prezygotic barriers to reproduction, thus reducing the chances of hybrid formation. Such a process is likely to occur only if hybrid offspring are less fit than members of the parent species.

Question 24

Punctuated Equilibria

Answer 24

In the fossil record, long periods of apparent stasis, in which a species undergoes little or no morphological change, interrupted by relatively brief periods of sudden change.