Chapter 16 - Evolution of Populations

Question 1

What is a gene pool?

Answer 1

Consists of all genes, including all the different alleles, that are present in a population

Question 2

What is the relative frequency of an allele?

Answer 2

the number of times that the allele occurs in a gene pool, compared with the number of times other alleles for the same gene occur

Question 3

How is relative frequency expressed as?

Answer 3

percentage

Question 4

In genetic terms, what is evolution?

Answer 4

any change in the relative frequency of alleles in a population

Question 5

What are the 2 main sources of genetic variation?

Answer 5

Mutations and genetic shuffling from sexual reproduction

Question 6

The number of phenotypes produced for a given trait depends on what?

Answer 6

How many genes control the trait

Question 7

What is a single-gene trait?

Answer 7

a trait controlled by a single gene

Question 8

How many phenotypes does a single-gene trait have?

Answer 8

2

Question 9

What is a polygenic trait?

Answer 9

trait controlled by 2 or more genes

Question 10

What is directional selection?

Answer 10

Individuals at one end of the curve have higher fitness than individuals in the middle or at the other end

Question 11

What is stabilizing selection?

Answer 11

Individuals near the center of the curve have higher fitness than the individuals at either end of the curve

Question 12

What is disruptive selection?

Answer 12

Individuals at the upper and lower ends of the curve have higher fitness than individuals near the middle

Question 13

What is genetic drift?

Answer 13

random change in allele frequency (chance)

Question 14

What size population does genetic drift mostly affect?

Answer 14

smaller ones

Question 15

How does genetic drift occur in small populations?

Answer 15

individuals that carry a particular allele may leave more descendants than other individuals just by chance

Question 16

What is founder effect?

Answer 16

a situation in which allele frequencies change as a result of the migration of a small subgroup of a population

Question 17

What is genetic equilibrium?

Answer 17

Situation in which allele frequencies remain constant

Question 18

What are the 5 conditions of the Hardy-Weinberg principle to remain genetic equilibrium?

Answer 18

1) must be random mating
2) large population
3) no movement into or out of the population
4) no mutations
5) no natural selection

Question 19

What is speciation?

Answer 19

formation of new species

Question 20

How does speciation occur?

Answer 20

The species have to become separated and isolated from each other

Question 21

What is reproductive isolation?

Answer 21

members of 2 populations cannot interbreed and produce fertile offspring

Question 22

What is behavioral isolation?

Answer 22

when 2 populations are capable of interbreeding but have differences in courtship rituals or reproductive behaviors

Question 23

What is geographic isolation?

Answer 23

2 populations are separated by geographic barriers such as rivers, mountains, or bodies of water

Question 24

What is temporal isolation?

Answer 24

2 or more species reproduce at different times