Genes within populations

Question 1

What is frequency dependent selection?

Answer 1

Fitness of phenotype depends on frequency

Question 2

What is negative frequency dependent selection?

Answer 2

Rare phenotype is favored. May go unnoticed by predators. May have fewer competitors. Leads to increased variation.

Question 3

What is positive frequency dependent selection?

Answer 3

Common phenotype favored.
May attract less attention. Reduces variation.

Question 4

What is oscillating selection?

Answer 4

Favors different phenotypes at different times. Maintains variation.

Question 5

What is heterozygote advantage?

Answer 5

Selection which favors individuals with both alleles. Heterozygote is favored over homozygote. Maintains variation-maintains both alleles in population.

Question 6

What are the three types of selection?

Answer 6

1. Disruptive
2. Directional
3. Stabilizing

Question 7

What is disruptive selection?

Answer 7

Eliminates immediate forms

Question 8

What is directional selection?

Answer 8

Eliminates one extreme, often occurs when environment changes.

Question 9

What is stabilizing selection?

Answer 9

Eliminates extremes. Intermediate becomes more common.

Question 10

What is genetic variation?

Answer 10

Differences in alleles of genes found within individuals of a population.

Question 11

Natural selection can lead to what?

Answer 11

Changes in allele frequencies

Question 12

What are allele frequencies?

Answer 12

Frequencies of alleles of a gene from generation to generation.

Question 13

What was historically used as a proxy for genetic variation?

Answer 13

Morphological variation

Question 14

What are single nucleotide polymorphisms?

Answer 14

Single nucleotide differences between individuals

Question 15

Proportions of genotypes in a population do not change as long as what?

Answer 15

1. No mutation takes place
2. No genes are transferred from other source
3. Random mating is occurring
4. The population is very large
5. No selection occurs

Question 16

Population that meet those 5 criteria are said to be what?

Answer 16

Be in the Hardy-Weinberg equilibrium

Question 17

What is the equation for the 2 alleles?

Answer 17

p2+2pq+q2=1

Question 18

When violated these assumptions become?

Answer 18

Agents of evolutionary change

Question 19

What are mutations?

Answer 19

Changes in a cell’s DNA

Question 20

What is gene flow?

Answer 20

Movement of alleles from one population to another.

Question 21

What is nonrandom mating?

Answer 21

Mating with specific genotypes

Question 22

What is assortative mating?

Answer 22

When phenotypically alike individuals mate

Question 23

What is disassortative mating?

Answer 23

When phenotypically different individuals mate.

Question 24

What is sexual selection?

Answer 24

Certain genotypes are favored because of their competitive advantage in mating.

Question 25

What is genetic drift?

Answer 25

Random fluctuations overtime by chance. Magnitude of genetic drift is based on population size.

Question 26

What is the founder effect?

Answer 26

When few individuals found a new population. Small allelic pool.

Question 27

What is the bottleneck effect?

Answer 27

Drastic reduction in population and therefore gene pool size.

Question 28

What are the 3 things that have to happen for natural selection to occur?

Answer 28

1. Variation must exist among individuals in a population
2. Variation among individuals must result in differences in number of offspring surviving in next generation.
3. Variation must have a genetic basis

Question 29

What is fitness?

Answer 29

Measure of a probable genetic contribution to succeeding generations.

Question 30

Fitness is a combination of what 3 things?

Answer 30

1. survival
2. mating success
3. number of offspring per mating