Variation

• What is variation in biological terms?

  Variation is the sum of differences within and between species
• What is variation between species called?

  Interspecific variation
• What is variation within species called?

  Intraspecific variation
• What are the main causes of variation?

  • Genetic causes:
  • Alleles
  • Mutations (changes in DNA)
  • Meiosis (independent assortment and crossing over)
  • Sexual reproduction (alleles from different individuals)
  • Chance (random fertilization)
  • Environmental causes:
  • Factors affecting growth and development (e.g., sunlight, nutrition)
• How do sexually reproducing species compare in terms of variation?

  Sexually reproducing species show greater variation
• What are examples of traits influenced by both genetic and environmental factors?

  • Height
  • Skin colour
• How do genetic and environmental factors interact to cause variation?

  Most variation is caused by a combination of genetic and environmental factors