Ch. 23 - The Evolution of Populations

Question 1

A change in allele frequencies in a population over generations

Answer 1

Microevolution

Question 2

Differences among individuals in the composition of their genes or other DNA sequences

Answer 2

Genetic variation

Question 3

A measure of the genetic variability within a population

Answer 3

Average heterozygosity

Question 4

Genetic variation at the whole-gene level

Answer 4

Gene variability

Question 5

Differences among populations in genetically based traits across the natural geographic range of a species

Answer 5

Geographic variation

Question 6

Differences in DNA sequence that do not confer a selective advantage or disadvantage

Answer 6

Neutral variation

Question 7

A measurable gradient in a single character of a species across its geographical range

Answer 7

Cline

Question 8

A change in the nucleotide sequence of an organism’s DNA

Answer 8

Mutation

Question 9

A group of individuals of the same species that live in the same area and interbreed, producing fertile offspring

Answer 9

Population

Question 10

All copies of every type of allele at every locus in all members of the population

Answer 10

Gene pool

Question 11

In a population that is not evolving, allele and genotype frequencies will remain constant from generation to generation, provided that only Mendelian segregation and recombination of alleles are at work

Answer 11

Hardy-Weinberg equilibrium

Question 12

A process in which traits that enhance survival or reproduction tend to increase in frequency over time

Answer 12

Adaptive Selection

Question 13

A process in which chance events cause unpredictable fluctuations in allele frequencies from one generation to the next.

Answer 13

Genetic Drift

Question 14

When a few individuals become isolated from a larger population, this smaller group may establish a new population whose gene pool differs from the source population

Answer 14

Founder Effect

Question 15

Genetic drift that occurs when the size of a population is reduced, as by a natural disaster or human actions. Typically, the surviving population is no longer genetically representative of the original population.

Answer 15

Bottleneck Effect

Question 16

The transfer of alleles into or out of a population due to the movement of fertile individuals or their gametes.

Answer 16

Gene Flow

Question 17

The contribution an individual makes to the gene pool of the next generation relative to the contributions of other individuals.

Answer 17

Relative Fitness

Question 18

Natural selection in which individuals at one end of the phenotypic range survive or reproduce more successfully than do other individuals.

Answer 18

Directional Selection

Question 19

Natural selection in which individuals on both extremes of a phenotypic range survive or reproduce more successfully than do individuals with intermediate phenotypes.

Answer 19

Disruptive Selection

Question 20

Natural selection in which intermediate phenotypes survive or reproduce more successfully than do extreme phenotypes.

Answer 20

Stabilizing Selection

Question 21

A process in which individuals with certain inherited characteristics are more likely than other individuals of the same sex to obtain mates.

Answer 21

Sexual Selection

Question 22

Differences between the secondary sex characteristics of males and females of the same species.

Answer 22

Sexual Dimorphism

Question 23

A form of natural selection in which there is direct competition among individuals of one sex for mates of the opposite sex.

Answer 23

Intrasexual Selection

Question 24

A form of natural selection in which individuals of one sex (usually the females) are choosy in selecting their mates from the other sex; also called mate choice.

Answer 24

Intersexual Selection

Question 25

Genetic variation that does not provide a selective advantage or disadvantage.

Answer 25

Neutral Variation

Question 26

Natural selection that maintains two or more phenotypic forms in a population.

Answer 26

Balancing Selection

Question 27

Selection in which the fitness of a phenotype depends on how common the phenotype is in a population.

Answer 27

Frequency-Dependent Selection

Question 28

Greater reproductive success of heterozygous individuals compared with homozygotes; tends to preserve variation in a gene pool.

Answer 28

Heterozygote Advantage

Question 29

# Define the following term: Microevolution

Answer 29

A change in allele frequencies in a population over generations

Question 30

# Define the following term: Genetic variation

Answer 30

Differences among individuals in the composition of their genes or other DNA sequences

Question 31

# Define the following term: Average heterozygosity

Answer 31

A measure of the genetic variability within a population

Question 32

# Define the following term: Gene variability

Answer 32

Genetic variation at the whole-gene level

Question 33

# Define the following term: Geographic variation

Answer 33

Differences among populations in genetically based traits across the natural geographic range of a species

Question 34

# Define the following term: Neutral variation

Answer 34

Differences in DNA sequence that do not confer a selective advantage or disadvantage

Question 35

# Define the following term: Cline

Answer 35

A measurable gradient in a single character of a species across its geographical range

Question 36

# Define the following term: Mutation

Answer 36

A change in the nucleotide sequence of an organism's DNA

Question 37

# Define the following term: Population

Answer 37

A group of individuals of the same species that live in the same area and interbreed, producing fertile offspring

Question 38

# Define the following term: Gene pool

Answer 38

All copies of every type of allele at every locus in all members of the population

Question 39

# Define the following term: Hardy-Weinberg equilibrium

Answer 39

In a population that is not evolving, allele and genotype frequencies will remain constant from generation to generation, provided that only Mendelian segregation and recombination of alleles are at work

Question 40

# Define the following term: Adaptive Selection

Answer 40

A process in which traits that enhance survival or reproduction tend to increase in frequency over time

Question 41

# Define the following term: Genetic Drift

Answer 41

A process in which chance events cause unpredictable fluctuations in allele frequencies from one generation to the next.

Question 42

# Define the following term: Founder Effect

Answer 42

When a few individuals become isolated from a larger population, this smaller group may establish a new population whose gene pool differs from the source population

Question 43

# Define the following term: Bottleneck Effect

Answer 43

Genetic drift that occurs when the size of a population is reduced, as by a natural disaster or human actions. Typically, the surviving population is no longer genetically representative of the original population.

Question 44

# Define the following term: Gene Flow

Answer 44

The transfer of alleles into or out of a population due to the movement of fertile individuals or their gametes.

Question 45

# Define the following term: Relative Fitness

Answer 45

The contribution an individual makes to the gene pool of the next generation relative to the contributions of other individuals.

Question 46

# Define the following term: Directional Selection

Answer 46

Natural selection in which individuals at one end of the phenotypic range survive or reproduce more successfully than do other individuals.

Question 47

# Define the following term: Disruptive Selection

Answer 47

Natural selection in which individuals on both extremes of a phenotypic range survive or reproduce more successfully than do individuals with intermediate phenotypes.

Question 48

# Define the following term: Stabilizing Selection

Answer 48

Natural selection in which intermediate phenotypes survive or reproduce more successfully than do extreme phenotypes.

Question 49

# Define the following term: Sexual Selection

Answer 49

A process in which individuals with certain inherited characteristics are more likely than other individuals of the same sex to obtain mates.

Question 50

# Define the following term: Sexual Dimorphism

Answer 50

Differences between the secondary sex characteristics of males and females of the same species.

Question 51

# Define the following term: Intrasexual Selection

Answer 51

A form of natural selection in which there is direct competition among individuals of one sex for mates of the opposite sex.

Question 52

# Define the following term: Intersexual Selection

Answer 52

A form of natural selection in which individuals of one sex (usually the females) are choosy in selecting their mates from the other sex; also called mate choice.

Question 53

# Define the following term: Neutral Variation

Answer 53

Genetic variation that does not provide a selective advantage or disadvantage.

Question 54

# Define the following term: Balancing Selection

Answer 54

Natural selection that maintains two or more phenotypic forms in a population.

Question 55

# Define the following term: Frequency-Dependent Selection

Answer 55

Selection in which the fitness of a phenotype depends on how common the phenotype is in a population.

Question 56

# Define the following term: Heterozygote Advantage

Answer 56

Greater reproductive success of heterozygous individuals compared with homozygotes; tends to preserve variation in a gene pool.