genetic diversity and natural selection

• genetic diversity is the number of different alleles of genes in a population
• natural selection only occurs if there is genetic diversity in the population]
• what is genetic diversity?

  number of different alleles of genes in a population
• adaptations can be

  • anatomical
  • physiological
  • behavioural
• natural selections

  1. new alleles for a gene created by random mutations
  2. if the new allele increases chances of survival in the environment then they are more likely to reproduce
  3. the advantageous allele is passed over generations
  4. the new allele will increase in frequency
• what are the 2 different types of selection

  directional selection and stabilising selection
• directional selection

  • one of the extremes has the selective advantage
  • occurs when there is a change in environment
  • the modal trait changes
  • an example Is antibiotic resistance
• stabilising selection

  • modal trait had the selective advantage
  • occurs when there's no change in environment
  • modal trait remains the same
  • standard deviation decreases as the extreme traits decreases
  • eg. human birth weights
• what is evolution?

  change in allele frequency over many generations