Topic 7

Question 1

What is a change in allele frequencies in populations over generations?

Answer 1

Microevolution

Question 2

A _ is the combination of two alleles.

Answer 2

Gene

Question 3

The term for all the alleles present in all individuals in the population is:

Answer 3

Gene pool

Question 4

New genes and alleles arise by:

Answer 4

i) mutation

ii) gene duplication

Question 5

T/F: Mutations occur randomly and create new alleles

Answer 5

True

Question 6

What is something that can shuffle existing alleles into new combinations?

Answer 6

Sexual reproduction

Question 7

What are three major factors that alter allele frequencies and bring the most evolutionary changes?

Answer 7

i) Natural selection
ii) Genetic drift
iii) Gene flow

Question 8

What is directional selection?

Answer 8

It is natural selection that favours individuals at one end of the phenotypic range (one extreme phenotype)

Question 9

What is disruptive selection?

Answer 9

It is natural selection that favours individuals at both extremes of the phenotypic range

Question 10

What is stabilizing selection?

Answer 10

It is natural selection that favours intermediate or common (median) phenotypes

Question 11

Is variance larger in disruptive selection or stabilizing selection?

Answer 11

Disruptive selection since there are two extremes that allow for variation whereas in stabilizing there is one median phenotype that is passed on

Question 12

What is genetic drift?

Answer 12

Random changes in allele frequency in a population (regardless of natural selection)

Question 13

Is genetic drift more likely in small or large populations?

Answer 13

Small (greater chance of deviation)

Question 14

T/F: Rare alleles are more likely to be lost due to genetic drift

Answer 14

True

Question 15

T/F: Genetic drift increases genetic variation in a population

Answer 15

False (decreases)

Question 16

T/F: Genetic drift causes evolutionary changes and creates adaptations

Answer 16

False (does not create adaptations)

Question 17

What effect is a sudden reduction in population size due to a change in the environment?

Answer 17

Bottleneck Effect

Question 18

What is the effect of the Bottleneck Effect?

Answer 18

Allele frequency in the next generation is different than the previous generation because there are only a few individuals that contribute to the next generation

Question 19

T/F: The bottleneck effect increases genetic variation in the surviving populations.

Answer 19

False (reduces)

Question 20

What effect occurs when a few individuals become isolated from a larger population?

Answer 20

Founder Effect

Question 21

What is the effect of the Founder Effect?

Answer 21

The small founding population has a small fraction of the total genetic variation present in the original population

Question 22

What is the movement of alleles between populations?

Answer 22

Gene flow

Question 23

What is an example of gene flow?

Answer 23

Ex. interbreeding, migration, pollen, etc

Question 24

T/F: Gene flow introduces new variation into the receiving population

Answer 24

True

Question 25

T/F: Gene flow counteracts genetic drift

Answer 25

True

Question 26

T/F: Gene flow speeds up adaptation of the receiving population

Answer 26

False

It slows adaptation of the receiving population

Question 27

T/F: Gene flow reduces variation in populations over time

Answer 27

False

Gene flow reduces variation BETWEEN populations over time

Question 28

What is genetic variation that does not confer a selective advantage or disadvantage?

Answer 28

Neutral variation

Question 29

What occurs when natural selection maintains stable frequencies of two or more alleles in a population?

Answer 29

Balancing selection

Question 30

What are two mechanisms of balancing selection?

Answer 30

i) Heterozygote advantage

ii) Frequency-dependent selection

Question 31

What occurs when heterozygotes have higher fitness than both homozygotes?

Answer 31

Heterozygote advantage

Ex. AS individuals in sickle cell anemia in malarial regions

Question 32

What do you call when fitness of phenotype declines if it becomes too common in the population? (Rare phenotype is more beneficial)

Answer 32

Frequency-dependent selection