Causes Of Evolution

Question 1

Describe evolution

Answer 1

• a change in the phenotypical or genotypical composition of a population over time
• occurs when allele frequencies in populations change
• evolution occurs between generations

Question 2

Describe random genetic drift

Answer 2

Random variation in allele frequencies from one generation to the next caused by;
- mandelian segregation and finite population size

The impact of genetic drift is proportional to population size
- drift is greater in small populations

Question 3

Describe founder effect and bottleneck in terms of random genetic drift

Answer 3

Founder effect: the reduced genetic diversity which results when a population is descended from a small number of colonising ancestors

Bottleneck: an event that drastically reduces the size of a population

Question 4

Define biological fitness

Answer 4

• the biological fitness of a genotype is a measure of the individuals ability to survive and reproduce

Question 5

Define relative fitness

Answer 5

The ability of a genotype to survive and reproduce compared with other genotypes in the population

Question 6

Name two consequences of selection

Answer 6

• the allele with the higher average fitness increases the population
• the course of selection only depends on the relative fitness of the genotypes

Question 7

Describe mutation

Answer 7

• mutation is the fundamental source of genetic variation which provides the fuel for natural selection
• increases the frequency of mutant alleles

Question 8

Describe equilibrium

Answer 8

• Many forces are acting together - mutation, random genetic drift, selection
• there is often an equilibrium reached between these forces