8- gene pools

Question 1

changes in allele frequencies can be due to

Answer 1

• Selection pressures acting on a gene pool: Stabilising selection / disruptive selection.
• Chance: Genetic drift.
• Small population sizes: Genetic bottleneck / founder effect.

Question 2

gene pool

Answer 2

The total number of alleles of all genes present in a population at a given time.

Question 3

how does selection pressures acting on a gene pool

Answer 3

• Stabilising selection:
- Reduces variation in the population.
- Selects against extreme phenotypes.
- Conserves phenotypes already present.
• Disruptive selection:
- Increases variation in the population.
- Selects for extreme phenotypes.
- May result in 2 separate species if it occurs over a very long period of time.

Question 4

genetic drift

Answer 4

• A change in allele frequency due to the random nature of mutations.
• Occurs in and has a greater impact on smaller populations.
• Chance dictates which alleles are passed on.

Question 5

small population sizes- genetic bottleneck

Answer 5

• An event that causes a big reduction in a population’s size.
• This reduces the gene pool and genetic diversity.
• Survivors are often not genetically representative of the original population.

Question 6

small population sizes- founder effect

Answer 6

• The loss of genetic diversity when a few individuals start a new population.
• This reduces the gene pool and genetic diversity.

Question 7

conditions for HW equation

Answer 7

• No mutations.
• Random mating.
• Large isolated population.
• No selection pressure.

Question 8

equation for a population in genetic equilibrium

Answer 8