4.4 Genetic diversity and adaptation

Question 1

What is genetic diversity?

Answer 1

Number of different alleles in a population

Question 2

What are alleles?

Answer 2

• Variations of a particular gene / different DNA base sequence
• Arise by mutation

Question 3

What is a population?

Answer 3

• A group of organisms of the same species in a particular space at a particular time
• That can potentially interbreed to produce fertile offspring

Question 4

What is evolution?

Answer 4

• Change in allele frequency over many generations in a population
• Occurring through the process of natural selection

Question 5

How does natural selection occur?

Answer 5

• Random gene mutations result in new NAMED allele
• In certain environments, this new allele may benefit possessor, giving organism a selective advantage
• Possessors are more likely to survive and reproduce (increased reproductive success)
• Advantageous allele is inherited by offspring
• Over many generations, NAMED allele increases in frequency in the population

Question 6

What types of adaptations are there?

Answer 6

• Anatomical / structural
• Physiological / chemical
• Behavioural

Question 7

Directional selection

Answer 7

Organisms with an extreme variation of a trait have a selective advantage (eg. Bacteria with high level of antibiotic resistance)
Increased frequency of alleles for extreme trait
Normal distribution curve shifts towards extreme trait

Question 8

Stabilising selection

Answer 8

Organisms with average variation of a trait (eg. Babies with average birth weight)
Increased frequency of alleles for average trait
Normal distribution curve similar but less variation around the mean