11.5 - Calculating Genetic Biodiversity

Question 1

As the number of alleles change (up or down) what happens to genetic biodiversity?

Answer 1

As number of alleles increase genetic biodiversity increases

As number of alleles decrease genetic biodiversity decreases

Question 2

What factors increase genetic biodiversity?

Answer 2

1. Mutation(s) – of organism’s DNA (change in genetic material of organism affecting phenotype)
2. Gene flow – the transfer of alleles from one population to another by interbreeding (e.g. individuals of one population migrate to the habitat of another breed, and then mate)

Question 3

State the names of factors which decrease genetic biodiversity.

Answer 3

• Selective breeding
• Captive breeding
• Rare breeds
• Artificial cloning
• Natural selection
• Genetic bottlenecks
• Founder effect
• Genetic drift

Question 4

Define:

• Selective breeding
• Captive breeding
• Rare breeds

Answer 4

1. Selective breeding (artificial selection) –individuals of a population with desirable characteristics are chosen to be bred
2. Captive breeding – in zoos/conservation centres. Only a small number of captives are available for breeding – this is due to the wild population being endangered
3. Rare breeds – when selective breeding has been used, and the once desirable characteristics are no longer desirable, the breed numbers fall rapidly. Only have specific alleles for traits that were desirable - genetic biodiversity will be low as the individuals and their offspring have specific alleles.

Question 5

Define:

• Founder effect
• Natural selection
• Artificial cloning

Answer 5

1. Artificial cloning – asexual reproduction – e.g. using cuttings to clone farmed plants.
2. Natural selection – species will evolve only to contain characteristics that have been advantageous, the less advantageous alleles will be lost mostly lost from the population
3. Founder effect – small numbers of species create a new colony, geographically isolated from their original habitat, making the initial gene pool small

Question 6

Define

• Genetic bottlenecks
• Genetic drift

Answer 6

1. Genetic drift – occurs in populations with low genetic biodiversity
   
   • change in frequency of an allele in a population
   • it is purely chance which alleles are passed from parents to offspring
   • So in a population with low genetic diversity, higher chance alleles are lost from the population
   • population more likely to be extinct due to disease or environmental change
2. Genetic bottlenecks – When a significant event occurs (e.g. disease or natural disaster) - many alleles are lost when population drops (reduces gene pool)
   
   • current population exists from few survivors so only their alleles are passed onto future generations

Question 7

How is genetic biodiversity measured?

Answer 7

• Measure polymorphism
  
  • polymorphic genes have >1 allele,
    
    • e.g. immunoglobin gene has different alleles – responsible for determining human blood type.
• Most genes are not polymorphic, they are monomorphic (only one allel for this gene)

Question 8

What formula is used to quantify genetic biodiversity?

Answer 8

Loci – position of gene on chromosome

proportion of polymorphic gene loci = no. of polymorphic gene loci/total no. of loci