Variation and Selection

Question 1

What is variation?

Answer 1

The differences that exists between individuals. Variation within a species can show a wide range of different phenotypes

Question 2

What causes genetic variation?

Answer 2

Mutations
Meiosis
Random fertilisation of gametes

Question 3

What is natural selection?

Answer 3

When the frequency of an allele in a population changes by evolution

Question 4

Explain the process of natural selection

Answer 4

1. Individuals of the same species vary due to different alleles
2. Predation, disease and competition create a struggle for survival
3. Individuals with phenotype that increases chance of survival are more likely to survive, reproduce and pass on their gene
4. Higher proportion of next generation will inherit the beneficial alleles
5. Frequency of beneficial allele in gene pool with increase from generation to generation

Question 5

Name the different types of natural selection

Answer 5

Stabilising selection
Directional selection
Disruptive selection

Question 6

What is stabilising selection?

Answer 6

Individual with alleles for characteristics towards the middle of the range are more likely to survive and reproduce. Occurs when an environment isn’t changing. Reduces range of possible phenotypes

Question 7

What is directional selection?

Answer 7

Individuals will alleles for a single extreme phenotype are more likely to survive and reproduce. In response to changes in the environment

Question 8

What is disruptive selection?

Answer 8

Individuals with alleles for extreme phenotypes at either ends of the range are more likely to survive and reproduce. Occurs when an environment favours more than 1 phenotype