Mechanisms of Evolution

Question 1

What are the 5 “violations” of Hardy-Weinberg equilibrium that cause changes in the makeup of a population’s gene pool?

Answer 1

1-No mutations
2-No migration into or out of the population(GENE FLOW)
3-Population is infinitely large
4-There’s random mating in the population
5-There is No natural Selection acting on the population

Question 2

What is the main source of new alleles?

Answer 2

Mutations

Question 3

What are common causes of DNA mutations?

Answer 3

UV exposure, X-rays, Smoking, etc.

Question 4

Are DNA mutations all that common?

Answer 4

No it doesn’t happen very often. B/c the rate of mutations is generally low
(About 10^-8 or 10^-9 changes per base pair of DNA per generation)

Question 5

How might a “beneficial” mutation be preserved in the gene pool?

Answer 5

May become advantageous if they enhance an organisms chances of survival and reproduction
(Ex. Parents pass of to offspring if mutation in the egg/sperm resulting in it getting into the gene pool)

Question 6

How does gene flow contribute to change in the genetic makeup of a population?

Answer 6

Those who come into a population bring their alleles with them, altering allele frequencies.

Question 7

Why is the impact of genetic drift” stronger” on a small population compared to a larger one?

Answer 7

___

Question 8

Explain: Why genetic drift is of particular concern to conservation biologists.

Answer 8

____

Question 9

Once an allele has been “lost” in a gene pool, what are the two ways in which it may “return” to the gene pool?

Answer 9

Mutations and through gene flow.

Question 10

How does assortative mating affect the genetic makeup of a population?

Answer 10

It Increases the Homozygotes and Decreases the Heterozygotes. Since its choosing mates w/ similar phenotypes to oneself.

Question 11

What is the effect of disassortative mating on a population?

Answer 11

It Decreases Homozygotes, and Increases the Heterozygotes.

Question 12

How does inbreeding affect genetic variability?

Answer 12

It increases the probability of lethal genotypes.

Question 13

Describe experimental evidence that demonstrates the importance of sexual selection in a population.

Answer 13

preserves the integrity of the gene pool of the species

Question 14

What does it mean when an organism is “fit” with respect to natural selection?

Answer 14

able to successfully reproduce certain phenotypes

Question 15

What are the 3 modes of action of Natural Selection?

Answer 15

• Stabilizing selection
• directional selection
• disruptive selection

Question 16

Stabilizing Selection-

Answer 16

reduces variation

Question 17

Directional Selection-

Answer 17

phenotype favors one extreme environment

Question 18

Disruptive Selection-

Answer 18

favors both extremes.

Intermediate phenotypes are not populous