4.2.2 Classification and Evolution

• Classification

  The process of naming and organising organisms into groups based on their characteristics
• Classification hierarchy

  Domain -> kingdom -> phylum -> class -> order -> family -> genus -> species
• Binomial naming

  Generic name - genus the organism belongs to, two closely related species will share the same genus

  Specific name - the species the organism belongs to
• Binomial naming system

  • universal
  • the same everywhere in the world
• Five Kingdoms

  Prokaryote, Protoctista, Fungi, Plantae, Animalia
• Three Domains

  Bacteria, Archaea, Eukarota
• How are organised into a kingdom?

  Based on similarities in observable characteristics
• How was the domain system of classification developed?

  By analysing molecular differences between organisms to determine their evolutionary relationships (phylogeny)
• Classification and phylogeny

  Classification - sorting organisms into groups

  Phylogeny - investigates evolutionary relationships between organisms
• Natural Selection

  • random mutations result in new alleles
  • some alleles provide an advantage against selection pressures
  • individuals are more likely to survive and reproduce
  • offspring receives the new allele and 'evolve' a new characteristics
• Darwin and Wallace


  • observed that birds have different beak shapes
  • concluded that birds with beak shapes most suited to the food they eat are more likely to survive and pass this beak shape to their offspring
• Fossil Evidence of Evolution

  Allows us to compare extinct organisms to today's organisms
• Genomic DNA evidence of Evolution

  Sequencing of genomes have shown how closely related we are to primates
• Molecular Evidence of Evolution

  Proteins are composed of the same 20 amino acids in all organisms
• Variation

  • Genetic - mutations, random fertilisation
  • Environment - climate, diet, culture
• Intraspecific variation


  variation within the SAME species
• Interspecific


  variation between DIFFERENT species
• Continuous variation


  Variation exists as a gradual change over a range (height, root length)
• Discontinuous


  Variation exists as distinct categories (blood group, bacteria shape)
• Spearman's rank correlation coefficient


  To measure correlation between two variables (the extent to which changing one variable affects the other variable)
• Interpreting Spearman's rank results

  • closer to 1 - more positive correlation
  • closer to -1 - more negative correlation
  • around 0 - no correlation
• Anatomical adaptation


  changes to body structure (e.g. oily fur)
• Physiological adaptation


  changes to bodily processes (e.g. venom production)
• Behavioural adaptation


  changes to actions (e.g. hibernation)
• Marsupial and Placental moles

  • live in different continents
  • share similar anatomical features as they adapted to similar environments
• Bacteria antibiotic resistance


  means that infections are harder to treat
• Pesticide resistance

  means entire crops could be destroyed