19.2 The cause of gene pool change

Question 1

Genetic diversity

Answer 1

The degree of genetic variation within a species of population

Question 2

The conditions of the Hardy Weinberg represents

Answer 2

an ideal situation that rarely, if ever, occurs in natural populations.

Question 3

Process that cause changes in gene pools:

Answer 3

genetic mutations
gene flow
non-random mating
genetic drift
natural selection

Question 4

Mutation

Answer 4

Change that occurs in the DNA of an individual

Question 5

An inheritable mutation

Answer 5

Has the potential to affect an entire gene pool

Question 6

Back mutations

Answer 6

These mutations reverse the effects of former mutations
- If the number of mutations from A to a are equal to the number of back mutations from a to A, then there are no net mutations

Question 7

The more genetic variation there is in a population….

Answer 7

the greater the chance that a variation will be present and provide a selective advantage in a changing environment.

Question 8

Gene Flow

Answer 8

describes the net movement of alleles from one population to another due to the migration of individuals

Question 9

The five agents of evolutionary change:

Answer 9

(A) mutation, a change in DNA
(B) gene flow, the migration of alleles from one population to another
(C) non-random mating, such as self-fertilization in flowers
(D) genetic drift, a change in allele frequencies in a small population due to a chance event
(E) natural selection for favourable variations.

Question 10

While gene flow increases genetic diversitiy in one population,….. as a result….

Answer 10

it reduces the genetic differences among populations.

adjacent populations tend to share many of the same alleles

Question 11

Random Mating (2)

Answer 11

• there is no way to predict which males will mate with which females or which females will mate with which males.
• The probability of any individuals with a specific genotype mating with another individual with a specific genotype depends on the allele frequencies in the population

Question 12

Inbreeding (with ex)

Answer 12

when closely related individuals breed together

- Self fertilization

Question 13

Genetic drift

Answer 13

a change in allele frequencies due to chance events in a small breeding population

Question 14

In general, large populations do not experience genetic drift because:

Answer 14

chance events are unlikely to affect overall allele frequencies

Question 15

Founder effect (4)+ex

Answer 15

• The gene pool change that occurs when a few individuals start a new isolated population
• New populations are formed by only a few individuals (founders)
• Ex: a single pregnant fruitfully gets carried by the wind to an unpopulated island where her offspring and her found a new colony
• Founders carry some but not all of the alleles in the original population’s gene pool.
• Lack of genetic diversity

Question 16

Bottleneck effect (2)+ex

Answer 16

Gene pool change that results from a rapid decrease in population size

survivors have only a subset of the alleles that were present before the population declined, the gene pool will lose diversity

• Overhunting had reduced the number of northern elephant seals to as few as 20

Question 17

Natural selection

Answer 17

The only process that leads directly to evolutionary adaptation.

occurs when a mutation produces a phenotype that gives one individual a survival advantage over another