Variation and selection mind map

Variation and selection

• Variation
  • Variation
    • Differences within a species
  • Continuous
    • Range between extremes
    • Body length, mass
    • Genes and environment
  • Discontinuous
    • No intermediates
    • ABO blood groups
    • Pea seed shape, colour
    • Genes only
  • Mutation
    • Genetic change
    • New alleles
  • Increase mutation rate
    • Ionising radiation
    • Some chemicals
  • Gene mutation Supplement
    • Random change in base sequence
  • Sources of variation Supplement
    • Mutation
    • Meiosis
    • Random mating
    • Random fertilisation
• Adaptive features
  • Adaptive feature
    • Inherited
    • Helps survive and reproduce
  • Polar bear
    • White fur camouflage
    • Fat insulation
  • Cactus
    • Spines
    • Thick stem stores water
  • Hydrophytes Supplement
    • Air spaces
    • Stomata on upper surface
  • Xerophytes Supplement
    • Thick waxy cuticle
    • Reduced leaf area
    • Water storage
• Selection
  • Natural selection
    • Variation
    • Many offspring
    • Struggle for survival
    • Alleles passed on
  • Adaptation Supplement
    • Population more suited over generations
  • Antibiotic resistance Supplement
    • Mutation
    • Resistant survive
    • Allele passed on
  • Selective breeding
    • Select
    • Cross
    • Select offspring
    • Many generations
  • Natural vs artificial Supplement
    • Environment selects
    • Humans select