Lecture 20- Population Genetics

Question 1

True or false: Phenotypes are either represented or not represented. There is no in between.

Answer 1

False; phenotypes often occur in a gradient (contrary to Mendelian genetics)

Question 2

What are the two ways in which a population can end up very small?

Answer 2

The bottleneck effect and the founder effect

Question 3

True or False: Rapid asexual reproduction often has frequent mutations

Answer 3

True

Question 4

What is consanguineous mating?

Answer 4

Mating between individuals who are closely related

Question 5

What does p represent in the Hardy-Weinberg equation?

Answer 5

Dominant homozygous frequency

Question 6

What is gene flow and what does it result in?

Answer 6

Movement of genetic information (alleles) between populations (tends to reduce the differences between populations over time)

Question 7

What is a fixed allele?

Answer 7

A fixed allele is an allele that is the only variant that exists for that gene in all the population (a fixed allele is homozygous for all members of the population)

Question 8

What does q represent in the Hardy-Weinberg equation?

Answer 8

Recessive homozygous frequency

Question 9

True or False: The recombination of chromosomes that occurs during sexual reproduction leads to new alleles

Answer 9

False; the only source of new alleles are mutations

Question 10

What is the founder effect?

Answer 10

The loss of genetic variation that occurs when a new population is established by a very small number of individuals from a larger population (limits number of alleles in the next generation)

Question 11

What is stabilizing selection?

Answer 11

Type of natural selection in which the population means stabilizes on a particular non-extreme trait (occurs when the extremes of a trait are selected against)

Question 12

What does pq represent in the Hardy-Weinberg equation?

Answer 12

Heterozygous frequency

Question 13

What is a gene pool?

Answer 13

All alleles of all genes in a population

Question 14

What is non-random mating?

Answer 14

Occurs when the probability that two individuals in a population will mate is not the same for all possible pairs of individuals (some choice/preference)

Question 15

What is allele frequency?

Answer 15

Relative proportion of a specific allele in a population

Question 16

True or False: Hardy-Weinberg equilibrium describes a population that is evolving

Answer 16

False; the Hardy-Weinberg equilibrium describes a population that is not evolving

Question 17

What is directional selection?

Answer 17

Mode of natural selection in which a phenotype is favored over other phenotypes, causing the allele frequency to shift over time in the direction of that phenotype

Question 18

What is a silent mutation?

Answer 18

Change in DNA sequence without a subsequent change in the amino acid or function of the protein

Question 19

What is the difference between the two Hardy-Weinberg formulae?

Answer 19

One formula yields the frequency of organisms (individuals) in a population whereas the shorter formula yields the frequency of alleles

Question 20

What is random mating?

Answer 20

Describes a situation in which all individuals of one sec are equally potential partners of all members of the opposite sex (mate choice has nothing to do with genotype)

Question 21

What is disruptive selection?

Answer 21

Type of natural selection that selects against the average individual in a population. This population would show phenotypes if both extremes but have very few individuals in the middle

Question 22

What is genetic drift?

Answer 22

Variation in the relative frequency of different genotypes in a small population (alleles are lost/ random events can dictate who survives/reproduces)

Question 23

What is the bottleneck effect?

Answer 23

Sharp reduction in the size of a population due to environmental effects (catastrophic event can lead to few survivors and subsequently limits the number of alleles in the next generation)

Question 24

What effect would the lack of gene flow have on population?

Answer 24

No gene flow (isolated populations)-> accumulation of differences between populations

Question 25

True or False: Allele frequencies in a gene pool tend to stay constant until altered by an outside force

Answer 25

True

Question 26

What are the differences between microevolution and macroevolution?

Answer 26

Microevolution refers to the shift of allele frequencies over generations (small gradual changes), whereas macroevolution results in changes significant enough to transcend the boundaries of a single species (taxonomic group)