4.3 Classification and Evolution

• Classification 


  process of naming and organising organisms based on their characteristics
• Eight classification groups

  1. Domain
  2. Kingdom
  3. Phylum
  4. Class
  5. Order
  6. Family
  7. Genus
  8. Species
• Advantage of binomial naming system

  Universal - same everywhere in the world
• Five Kingdoms


  1. Prokaryote
  2. Protoctista
  3. Fungi
  4. Plantae
  5. Animalia
• Three Domains


  1. Bacteria - prokaryotes, peptidoglycan cell walls no membrane bound organelles
  2. Archaea - closer to eukaryotes that bacteria, no peptidoglycan wall, in extreme environments
  3. Eukaryota - nucleas and membrane bound organelles, animals plants etc. more complex cell
• How was the classification system developed

  Analysing molecular differences to determine evolutionary relationships
• What is phylogeny 


  Investigates evolutionary relationships
• Natural selection 


  • Random mutations - new alleles
  • Some alleles provide advantage against selection pressures, making individual more likely to survive and reproduce
  • Offspring receive new allele
• Evidence for theory of evolution

  1. Darwin and Wallace's Theory of Evolution
  2. Fossils - compare extinct organisms to todays organisms
  3. Genomic DNA - sequence of genomes have show how closely related species are. highly conserved and found in all organisms
  4. Molecular - proteins composed of the same 20 amino acids in all organisms
• Causes of variation

  1. Genetic - mutations, random fertilisation
  2. Environmental - Climate, diet, culture
• Intraspecific variation

  variation within the same species
• Interspecific variation

  Variation between different species
• Continuous Variation

  1. Exists as gradual changes over a range
  2. Eg. height, foot length
• Discontinuous variation

  1. Variation as distinct categories
  2. Eg. Blood group and bacteria shape
• Spearman's Rank

  1. Measure correlation between two variables
  2. Closer to 1 - more positive correlation
  3. Closer to -1 - more negative correlation
  4. 0 - no correlation
• Three Types of Adaptation

  1. Anatomical - changes to body structure - oily fur
  2. Physiological - changes to bodily processes - venom production
  3. Behavioural - changes to actions - hibernation
• Taxonomy 


  Identifying, classifying and naming different organisms
• 3 Features of prokaryote

  1. unicellular
  2. no nucleus and membrane bound organelles
  3. 70s ribosomes
• Features of protoctista 


  1. unicellular
  2. nucleus and membrane bound organelles
  3. auto/heterotrophic
  4. eukaryotic
• Features of fungi


  1. chitin cell wall
  2. nucleus and membrane bound organelles
  3. no photosynthesis
  4. hyphae
• Advantages of phylogenetic classification

  1. can be done without reference to Linnaean classification
  2. Produces continuous tree
  3. Hierarchical
• Three pieces of evidence by the fossil record

  1. simple organisms found in oldest rocks
  2. more complex in recent rocks
  3. Similarities in anatomy show close relation between extinct and living organisms
• Why is the fossil record not complete

  1. soft bodied and decompose quickly
  2. Conditions for fossil formation not present
  3. destroyed by earthquake
  4. Undiscovered
• Divergent evolution


  Common ancestors evolving to different environment
• How does meiosis cause genetic variation

  • Independentant assortment
  • crossing over of alleles
• T-test

  Compare the means of data values of 2 populations
• Null hypothesis 


  Prediction that there is no significant difference between specified populations
• Convergent Evolution


  unrelated species share similar traits. Organisms adapt to similar environments/selection pressures
• Classification and Phylogeny

  • Classification is the process of grouping organisms based on shared characteristics
  • phylogeny is the evolutionary relationships
  • Modern classification systems aim to reflect phylogeny but grouping organisms that share a recent common ancestor
• Why might organisms from different taxonomic groups show similar anatomical features

  1. Convergent evolution
  2. similar environmental/selection pressures
  3. Anatomical features preform the same function but have different evolutionary origins
• Variation?

  Continuous

  
• Variation?

  Discontinuous