Chapter 23

Question 1

Genetic Varitation

Answer 1

diversity in gene frequencies

variation within a population
variation between populations

Question 2

Variation within a population

Answer 2

can be measured both at whole gene level and molecular level

Question 3

what makes up variation within a population

Answer 3

gene variability

Nucleotide variability

Question 4

what is gene variability?

Answer 4

average heterozygosity

Question 5

average heterozygosity measures…?

Answer 5

the average percent of loci that are heterozygous in a population

Question 6

what is nucleotide variability measure by?

Answer 6

comparing DNA sequences of two individuals in a population and then averaging the data from many such comparisons

Question 7

variation between populations

Answer 7

exists as geographic variation

Question 8

geographic variations

Answer 8

differences in genetic composition of separate populations

Question 9

Mutations (evolution)

Answer 9

changes in the nucleotide sequence of DNA

ultimate source of new alleles

Question 10

sexual reproduction

Answer 10

shuffles existing alleles into new combinations

contributes by providing unique combination

Question 11

Hardy-Weinberg

Answer 11

no differences = real population isnt evolving

differences = real population is evolving

Question 12

what are the conditions for Hardy-Weinberg equilibrium

Answer 12

no mutation
random mating
no natural selection
large population size
no gene flow

Question 13

3 mechanisms that alter allele frequency

Answer 13

Natural Selection
Genetic Drift
Gene Flow

Question 14

natural selection

Answer 14

individuals in a pop. exhibit variation in their heritable traits
better suited traits = more offspring

Question 15

genetic drift

Answer 15

when chance events cause allele frequencies to fluctuate unpredictably

Question 16

what are 2 types of genetic drift

Answer 16

founder effect

bottleneck effect

Question 17

founder effect

Answer 17

when few become isolated from a large population

Question 18

bottleneck effect

Answer 18

sudden reduction in population size

Question 19

gene flow

Answer 19

movement of alleles among populations

reduces differences in populations over time

Question 20

sexual selection

Answer 20

a form of natural selection

individuals with certain heritable characteristics are more likely to obtain a mate

Question 21

what are the 2 types of sexual selection

Answer 21

intrasexual selection

intersexual selection

Question 22

Intrasexual Selection

Answer 22

competition between 1 sex for a mate of the opposite sex (often males)

Question 23

Intersexual Selection

Answer 23

“mate choice”

occurs when individuals of one sex are choosy in selectung their mate

Question 24

ways to preserve genetic variation

Answer 24

Diploidy
Balancing Selection
Neutral Variation

Question 25

Diploidy

Answer 25

maintaining genetic variation in the form of hidden recessive alleles

Question 26

Balancing Selection

Answer 26

occurs when natural selection maintains stable frequencies of two or more phenotypic forms in a population

Question 27

What are two ways of balancing slelection

Answer 27

Heterozygous Advantage

Frequency-Dependent slection

Question 28

Heterozygous advantage

Answer 28

occurs when heterozygotes have a higher fitness then both homozygotes

Question 29

what is an example of heterozygous advantage?

Answer 29

sickle cell

Question 30

frequency-dependent selection

Answer 30

the fitness of a phenotype declines if it becomes to common

Question 31

neutral variation

Answer 31

genetic variation that appears to show no selective advantage or disadvantage