Unit 2; Continuity of Species; Classification

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  • Classification
    • Phylogenic Classifiation
      • look at history to group closely related animals
      • on a tree the further up you go, the further forward in time & branches represent common ancestors
    • Hierarchical Classification
      • breaks large groups into progressively smaller groups
      • Domain, Kingdom, Phylus, Class, Order, Family, Genus, Species
      • moving down from domain, organisms more closely related
    • Pros on Classification
      • infers evolutionary relationships
      • easy & quick
      • predict characteristics of new species
      • easy for conservation analysis
      • BUT some species fit in 1+ taxa e.g. platypus
    • 3 Domain
      • Eubacteria: prokaryotes
      • Archaea: prokaryotes with unusual metabolism
      • Eukaryota: plants, animals, fungi
    • 5 Kingdoms
      • Prokaryota: unicellular, no nucleus
      • Protoctista: unicellular, nucleus
      • Plantae: reproduce with spores or seeds
      • Fungi: multicellular decomposers
      • Animalia: heterotrophs
    • Relatedness of Organisms
      • homologous features; dif functions but similar structure & origin e.g. pentadactyl limb
        • show divergent evolution as evolved o dif structures
      • separate groups have common ancestor so share basic features
      • analogous features have structures evolve sim properties but from dif origin
        • convergent evolution as dif species adapted to similar environments
    • Assessing Relatedness
      • DNA sequences:
        • related species have DNA base sequence similarities
      • DNA Hybridisation:
        • DNA removed, cut to fragments & mixed with other species' DNA to form complementary base pairs
      • Amino acid sequencing:
        • degree of sim in amino acid sequence in same protein in 2 species
      • Immunology
        • mix species 1 antigens with species 2 antibodies
        • produce a precipitate, the more precipitate, the more closely related
    • Concept of Species
      • Morphological def:
        • if 2 organisms look similar then likely to be same species
        • takes 'sexual' dimorphism into account
      • Reproductive def:
        • same species if can interbreed to produce fertile offspring
    • Binomial System
      • taxonomy is identifcation & allows us to:
        • discover biological diversity
        • investigate evolutionary relationships
        • classify to show evo-relations
      • 2 identifying names
        • unambiguous meaning
        • Latin used world-wide
        • implies relatedness


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