Causes of variation

• Variation is the differences that exist between individuals in a population, most variation is due to individuals having different combinations of alleles producing different phenotypes

  • Can be caused by environmental or genetic causes, most is caused by a combination of both
• Genetic variation - The variation in the DNA sequence in each of our genomes
• Causes of variation: Environmental

  • Climate change
  • Availability of food/water (animals)
  • Intensity of light, availability of water and nutrients in soil (plants)
• Genetic cause of variation: Mutation

  • Random changes in DNA or changes to structure or number of chromosomes
• Genetic cause of variation: Meiosis

  • Through independent assortment of homologous chromosomes creating variation in gametes
  • Crossing over creating different allele combinations on chromosomes
• Genetic cause of variation: Fertilisation of gametes

  • This is random, and the new combinations of genes are produced by chance