Capter 21 - Microevolution

Question 1

Microevolution

Answer 1

A heritable change in the genetics of the population

Question 2

Gene pool

Answer 2

All of the alleles for every gene in a given population

Question 3

G.H. Hardy and Wilhelmina Weinberg proposed that a population will achieve genetic equilibrium if the following conditions are met:

If all five conditions are met, then the allele and genotype frequencies will never change.

Answer 3

1. No mutations occur
2. No natural selection(all offspring survive and reproduce)
3. Population size is infinitely large
4. No migration occurs between different populations
5. Mating is random

Question 4

Gene flow

Answer 4

Occurs when individuals migrate between populations with different allele frequencies

Question 5

Genetic drift

Answer 5

Will occur faster in smaller populations and reduced genetic variations through the loss of alleles

Question 6

To evaluate reproductive success, a member is given

Answer 6

A relative fitness

Question 7

Relative fitness

Answer 7

The number of surviving offspring g that an individual produces compared with the number left by others in the population

Question 8

Three modes of natural selection

Answer 8

1. Directional selection
2. Stabilizing selection
3. Disruptive selection

Question 9

1. Directional selection

Answer 9

Individuals at one extreme of a phenotypic range have a greater reproductive success in a particular environment

Question 10

2. Stabilizing selection

Answer 10

Favors the survival of individuals with intermediate phenotypes

Extreme values of a trait are selected against

Question 11

3. Disruptive selection

Answer 11

Favors the survival of both extreme phenotypes

Question 12

Sexual selection often

Answer 12

Exaggerates showy structures on males

Question 13

Sexual selection can occur in one of two ways

Answer 13

1. Intrasexual selection

2. Intersexual selection

Question 14

Intrasexual selection

Answer 14

Between members of the same sex

Males directly compete for mating opportunities or territories

Question 15

Intersexual selection

Answer 15

Between members of the opposite sex

Female chooses certain showy characteristics in males

Question 16

Two ways to maintain genetic variations

Answer 16

1. Heterozygous advantage

2. Frequency-dependent selection

Question 17

Heterozygote advantage

Answer 17

Occurs when heterozygotes have higher relative fitness than either homozygote

Example: individuals who are heterozygous for sickle cell have a higher relative fitness

Question 18

Frequency-dependent selection

Answer 18

Sometimes, genetic variability is maintained in a population because rare phenotypes have high relative fitness than the more common phenotypes.

When predators focus their attention on the most common type of prey, the phenotype with the low frequency has a selective advantage