Chapter 7 - Factors affecting alleles in a population

Question 1

What is evolution?

Answer 1

Any change in the heritable characteristics of a population over a number of generations.

This can be explained as a change in allele frequencies in a population

Question 2

Does evolution occur in individuals?

Answer 2

No.
Evolution occurs in populations not individuals

Question 3

How can evolution be analysed/measured?

Answer 3

By measuring allele frequencies in the population

Question 4

What is an allele frequency?

Answer 4

The number of time a particular allele is present in a population

Question 5

How is the allele frequency represented as?

Answer 5

A percentage or fraction of the population

Question 6

What is a gene pool?

Answer 6

All the alleles present in a population

Question 7

What are the three main ways new alleles are created?

Answer 7

• Mutation
• Genetic drift
• Gene flow

Question 8

State three criterias needed for a mutation to remain in the population.

Answer 8

• The mutation is germline mutation (heritable)
• Individuals with the new allele survive and reproduce
• The new allele is passed onto the offspring

Question 9

What is genetic drift?

Answer 9

The process of allele frequencies changing as a result of random chance/events.

It causes random changes to allele frequencies

Question 10

Is genetic drift always directional?

Answer 10

Not always.
Allele frequency can increase, decrease or stay the same.

Question 11

Is the effect of genetic drift for significant in smaller or larger populations?

Answer 11

Genetic drift is more significant in smaller populations

Question 12

How does genetic drift affect variation in a population?

Answer 12

Many alleles become fixed (are the only allele for that gene), or are lost from the gene pool.

Question 13

What are the two forms of genetic drift?

Answer 13

• Bottleneck effect
• Founders effect

Question 14

What is the bottleneck effect?

Answer 14

Occurs when the population is drastically reduced in size by a sudden & unexpected environmental change.
example - flood, bushfires, storms

It is unlikely the allele frequency will ever be the same as the original

Question 15

What is the founders effect?

Answer 15

Occurs when a small portion of the original population moves to a new location.

The allele frequencies of the founding population are not the same as the original population

Question 16

What is gene flow?

Answer 16

Gene flow is the movement of individuals and the alleles they carry, into or out of the population.

The more gene flow between populations, the more similar the allele frequencies.