Ch 25 Population Genetics

Question 1

branch of genetics that studies genetic makeup of groups of individuals and how genetic composition of a group changes over time

Answer 1

population genetics

Question 2

group of interbreeding, sexually reproducing individuals that have a common set of genes

Answer 2

Mendelian population

Question 3

what leads to a loss of genetic variation?

Answer 3

genetic drift

Question 4

what is the basis for all evolution?

Answer 4

genetic variation

Question 5

what are the assumptions of the Hardy-Weinberg law?

Answer 5

• large population
• randomly mating
• not affected by mutation, migration, or natural selection

Question 6

if a population is in Hardy-Weinberg equilibrium, what does it mean about the population?

Answer 6

the population is not evolving

Question 7

when is the heterozygote frequency at its maximum?

Answer 7

when each allele frequency (p & q) are 0.5

Question 8

if a population is in Hardy Weinberg equilibrium, have forces (natural selection, mutation, and migration) have acted since random mating last took place?

Answer 8

no, these forces have no acted since random mating last took place

Question 9

describe the two types of nonrandom mating

Answer 9

positive assortment mating - tendency for like individuals to mate
negative assortment mating - tendency for unlike individuals to mate

Question 10

preferential mating between related individuals

Answer 10

inbreeding

Question 11

preferential mating between unrelated individuals

Answer 11

outcrossing

Question 12

when inbreeding occurs, does the heterozygote population increase or decrease?

Answer 12

heterozygotes decrease

Question 13

describe inbreeding depression and what causes it

Answer 13

decreased fitness of a population due to inbreeding, often because of increased appearance of lethal or deleterious traits

Question 14

describe how mutations change allelic frequencies

Answer 14

mutations can increase the allele frequency at one locus, thus decreasing the frequency of the other, until they eventually reach mutational equilibrium

Question 15

what is gene flow/migration?

Answer 15

movement of genes from one population to another

Question 16

what are the two overall effects of migration?

Answer 16

• prevents populations from being genetically different from one another
• increases genetic variation within a population

Question 17

what is genetic drift?

Answer 17

change in allele frequencies due to chance when sample size is small

Question 18

what is founder effect?

Answer 18

establishment of a population by a small number of individuals, where the genes depend on the genes of the founders

Question 19

what is bottleneck effect?

Answer 19

a population undergoes a drastic reduction in size, where the genes depend on the survivors

Question 20

what are the effects of genetic variation?

Answer 20

• change in allelic frequencies
• reduction in genetic variation within populations
• different populations diverge genetically from one another

Question 21

occurs when an allele reaches a frequency of 1; all are homozygous for that one allele

Answer 21

fixation

Question 22

what is natural selection?

Answer 22

differential reproduction of genotypes, where individuals with adaptive traits reproduce more than others

Question 23

relative reproductive success of a genotype

Answer 23

fitness