ch. 21 (population and evolutionary genetics)

Question 1

The probability that two alleles present in a zygote are descended from a common ancestor.

Answer 1

coefficient of inbreeding (F)

Question 2

A selective force that changes the frequency of an allele in a given direction, either toward fixation or toward elimination.

Answer 2

directional selection

Question 3

Simultaneous selection for phenotypic extremes in a population, usually resulting in the production of two phenotypically discontinuous strains.

Answer 3

disruptive selection

Question 4

A measure of the relative survival and reproductive success of a given individual or genotype.

Answer 4

fitness

Question 5

A form of genetic drift. The establishment of a population by a small number of individuals whose genotypes carry only a fraction of the different alleles present in the parental population.

Answer 5

founder effect

Question 6

The total of all alleles possessed by the reproductive members of a population

Answer 6

gene pool

Question 7

A drastic reduction in the size and genetic variation present in a population. These events can be triggered by environmental disasters (volcanic eruptions, earthquakes, floods, etc.) or human activity (habitat destruction, hunting to near-extinction, etc.). Also known as a population bottleneck.

Answer 7

genetic bottleneck

Question 8

Random variation in allele frequency from generation to generation, most often observed in small populations.

Answer 8

genetic drift

Question 9

The principle that genotype frequencies will remain in equilibrium in an infinitely large, randomly mating population in the absence of mutation, migration, and selection.

Answer 9

Hardy-Weinberg law

Question 10

Mating between closely related organisms.

Answer 10

inbreeding

Question 11

In evolutionary studies, a method that counts the number of differences in DNA or protein sequences as a way of measuring the time elapsed since two species diverged from a common ancestor.

Answer 11

molecular clock

Question 12

The idea that most of the genetic variation present within and between species is caused by random fixation of alleles that are not acted on by natural selection and are therefore selectively neutral or nearly neutral mutations.

Answer 12

neutral theory

Question 13

The extraction and analysis of DNA from the fossils of extinct organisms.

Answer 13

paleogenomics

Question 14

A local group of actually or potentially interbreeding individuals belonging to the same species.

Answer 14

population

Question 15

A factor that prevents or reduces inbreeding by acting after fertilization to produce nonviable, sterile hybrids or hybrids of lowered fitness.

Answer 15

postzygotic isolation mechanism

Question 16

A factor that reduces inbreeding by preventing courtship, mating, or fertilization.

Answer 16

prezygotic isolation mechanism

Question 17

The set of environmental, physiological, behavioral, or mechanical impediments that prevent or reduce interbreeding between populations.

Answer 17

reproductive isolating mechanisms

Question 18

The process by which new species arise.

Answer 18

speciation

Question 19

A group of actually or potentially interbreeding individuals that is reproductively isolated from other such groups.

Answer 19

species

Question 20

Preferential reproduction of individuals with genotypes close to the mean for the population. A selective elimination of genotypes at both extremes.

Answer 20

stabilizing selection