Chapter 21

Question 1

What’s microevolution?

Answer 1

microevolution is when the ALLELE FREQUENCY changes in a population over GENERATIONS

Question 2

What’s GENETIC DRIFT?

Answer 2

genetic drift are CHANCE EVENTS that change the allele frequency

Question 3

What’s GENE FLOW?

Answer 3

gene flow is the TRANSFER OF ALLELES between populations

Question 4

What do mutations do?

Answer 4

form new alleles

Question 5

What’s a POPULATION?

Answer 5

a population is a group of individuals of the same species that live together and make offspring together.

Question 6

What’s a GENE POOL?

Answer 6

a gene pool is all the alleles in a population

Question 7

What’s a FIXED allele?

Answer 7

a fixed allele is when only one allele exists for a particular locus in a population

Question 8

When is a system in hardy-weinberg equilibrium?

Answer 8

a system is in hardy-weinberg equilibrium when a population WON’T EVOLVE if only MENDELIAN SEGREGATION and ALLELE RECOMBINATION occur

Question 9

What’re the conditions of hardy-weinberg? (5)

Answer 9

conditions of hardy-weinberg:

1. no mutations
2. there’s random mating
3. no natural selection
4. the population is large
5. no gene flow

Question 10

What happens if a system does not meet the conditions of hardy Weinberg and isn’t in hardy-weinberg equilibrium?

Answer 10

then that system EVOLVES

Question 11

What’s the founder effect?

Answer 11

the founder effect is when a few individuals are isolated and create a new and different gene pool

Question 12

What’s the bottleneck effect?

Answer 12

the bottleneck effect is when a severe drop in the population size decreases genetic variation

Question 13

What’re the effects of genetic drift?

Answer 13

effects of genetic drift:

1. genetic variation decreases
2. some alleles become fixed
3. some alleles are lost by chance

Question 14

What’s an organism’s relative fitness?

Answer 14

relative fitness is the contribution an individual makes to the gene pool of the next generation relative to the contributions of other individuals

Question 15

What’s DIRECTIONAL selection?

Answer 15

directional selection is when conditions favor individuals at ONE EXTREME of a phenotypic range

Question 16

What’s DISRUPTIVE selection?

Answer 16

disruptive selection is when conditions favor individuals at BOTH EXTREMES of a phenotypic range.

Question 17

What’s STABILIZING selection?

Answer 17

stabilizing selection is when conditions favor individuals in the MIDDLE of a phenotypic range.

Question 18

What does sexual selection result in?

Answer 18

Sexual selection results in SEXUAL DIMORPHISM

Question 19

What’s sexual dimorphism?

Answer 19

sexual dimorphism is when males and females have DIFFERENT sexual characteristics.
- size, color, etc.

Question 20

What’s INTRASEXUAL selection?

Answer 20

intrasexual selection is when members of one sex COMPETE WITH OTHERS for mates

Question 21

What’s INTERSEXUAL selection?

Answer 21

intersexual selection is when members of one sex CHOOSE their mates

Question 22

What’re NEUTRAL variations?

Answer 22

neutral variation are differences in DNA that don’t give you an advantage OR disadvantage
- they have no effect on fitness.

Question 23

What’s the HETEROZYGOTE ADVANTAGE?

Answer 23

the heterozygote advantage is when heterozygotes are more fit than homozygotes.

Question 24

What’s FREQUENCY-DEPENDENT selection?

Answer 24

frequency-dependent selection is when the fitness of a phenotype depends on how common it is in the population.