Genetic diverstiy

• What is genetic diversity?

  Number of different alleles of genes in a population
• What are alleles and how do they arise?

  ● Variations of a particular gene (same locus)→ different DNA base sequence

  ● Arise by mutation
• What is a population?

  A group of interbreeding individuals of the same species.
• Explain the importance of genetic diversity

  ● Enables natural selection to occur

  ● As in certain environments, a new allele of a gene might benefit its possessor

  ● By resulting in a change in the polypeptide coded for that positively changes its properties

  ● Giving possessor a selective advantage (increased chances of survival and reproductive success)
• What is evolution?

  ● Change in allele frequency over many generations in a population

  ● Occurring through the process of natural selection
• Explain the principles of natural selection in the evolution of populations

  1 Mutation = Random gene mutations can result in new alleles of a gene

  2. Advantage= In certain environments, the new allele might benefit its possessor→ organism has a selective advantage

  3. Reproductive success = Possessors are more likely to survive + have increased reproductive success

  4. Inheritance = Advantageous allele is inherited by members of the next generation

  5. Allele frequency = Over many generations, allele increases in frequency in the population
• Describe 3 types of adaptations

  ● Anatomical- structural / physical features that increase chance of survival

  ● Physiological- processes / chemical reactions that increase chance of survival

  ● Behavioural- ways in which an organism acts that increase chance of survival
• Explain Direction selection

  ●Example : Antibiotic resistance in bacteria

  ●who has a selective advantage? Organisms with an extreme variation of a trait eg. bacteria with high level of resistance to a particular antibiotic

  ●Change in environment? Yes, usually eg. antibiotic introduced

  ●Effect on population over many generations:

  ○ Increased frequency of organisms with / alleles for extreme trait

  ○ Normal distribution curve shifts towards extreme trait
• Explain stabilising selection

  ●Example: Human birth weight

  ● who has a selective advantage?:Organisms with an average / modal variation of a trait eg. babies with an average weight

  ●Change in environment?: no, usually stable

  ●Effect on population over many generations

  ○ Increased frequency of organisms with / alleles for average trait

  ○ Normal distribution curve similar, less variation around the mean