Biodiversity, Evolution & Classification

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Biodiversity

  • human alteration to habitat is the single greatest threat to biodiversity
    • destroying tropical rainforests
    • overfishing
    • clearing lands for crop production/human populations
  • extinction is a natural process occuring since the first life evolved
    • current rate underlies biodiversity problems
    • human activity increasing rate of extinction at alarming rate
    • mass destruction for farming agriculture urbanisation forestry mining drilling pollution
  • earlier extinctions e.g dinosaurs where a result of climatic geological biotic changes
  • main causes of loss of large mammals are loss of habitat over hunting and competition from introduced species, and deforestation pollution and wetland drainage
  • each species can represent an important human asset
    • food, chemicals, disease resistant genes
    • extinction of plant species with potential medicinal properties before being fully investigated could be an incalcuable loss
    • need for species consrvation and preservation of wildlife
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Evolution

  • processes that have transformed life on Earth from its early beginings tovast diversity of fossilised and living forms known
  • theory proposed by Charles Darwin
    • travelled to south america and galapogas islands formed in recent geological time by volcanic activity
    • studied flora and fauna on both lands- any plants on the islands must have reached via the mainland
    • observe describe and classify his findings, colecting fossils showing the different life forms of the past
    • natural selection was the force to cause changes in the populations
    • studied finches onislands, which are unable to fly long distances as such to reach the mainland
      • acestors of the finches reached the island by prevailing winds species flourished due to no other bird species and a variety of food individual finches differed in size and shape of beaks related to type of food eaten seeds fruit insects
      • characteristics best suited to the finch where passed to offspring, all finches had common ancestor type of beak developed through adaptie radiation via food
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Taxonomy & Phylogeny

  • sorting living groups of organisms into groups of a managable size
  • look for differences and similarities between organisms placing similar organisms close and different ones apart
  • hierarchical system devised to distinguish large groups of organisms with a series of rank names
  • kingdom, phylum, class, order, family, genus, species

phylogeny

  • taxonomic ranks based on evolutionary line of descent
  • phylogenic relationships represented by a tree 
  • oldest speces at the base while recent at the ends
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Binomial System

  • naming according to the binomial system based on latin 
  • each organism has two names, genus and species
  • precise identification worldwide
  • each organism has unique scientific name and allows for easy identification of relation to other species
    • genus name is the fiirst word and has a capital
    • species name comes second with no capital
    • first time used in a scientific text should be names in full afterwards it can be abbreviated
    • printed in italics or underlined
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5 Kingdom Classification

prokaryote

  • unicellular organisms incl. bacteria and blue green algae
  • no organelles
  • cell wall not of cellulose

proctoctista

  • small eukaryotic organisms
  • membrane bound organelles and nucleus
  • not plant animals or fungi incl. algae mouldss slime protozoa

fungi

  • eukaryotic with a body of a sytem of threads called hyphae forming a mycelium
  • rigid cell wall of chitin
  • no photosynthetic pigments; feed heterotrophically- saprophytic/parasitic
  • reproductionby spores w/o flagellum yeast mushroom
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5 Kingdom Classification p2

Plants

  • multicellular
  • carry out photosynthesis
  • eukaryotes with cellulose walls, vacuoles with cell sap & chloroplasts with photosynthetic pigments
  • mosses liverworts frns conifers flowering plants

animals 

  • multicellular
  • heterotrophic eukaryotes
  • cells do not have cell walls
  • nervous coordination
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Animal Kingdom Phyla - annelida

  • non-chordates/invertebrates 
  • chordates- vertebrates with a vertebral column

annelida

  • earthworms leeches
  • long thin segmented ringed body separated internally by septa
  • fluid filled body cavity
  • hydrostatic skeleton
  • head with primative brain/nervous system
  • thin permeable skin for gaseous exchange
  • closed circulatory system with repiratory pigment
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Arthropoda

  • body divided into segments
  • well developed brain
  • open circlatory system/cavity surrounding body organs
  • hard outer exoskeleton
  • paired jointed legs
  • key features 
    • joined legs modified for a variety of functions swimming jumping walking
    • exoskeleton for protection of internal organs, attachment of muscle, suppor, reducing water loss
    • exoskeleton does not grow- must be shed leaving animal vunerable
  • classes
    • crustacea 10-20 pairs of legs
    • spiders 4 pairs
    • insects 3 pairs
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Arthropoda Insecta

  • most successful group- inhabt most habitats and air
  • adult insects have different features to other arthropods
    • 3 pairs of legs, one to each segment of thorax
    • head has antennae and compound eyes
    • gas exchange by gills in aquatic forms and tracheae in terrestrial
    • evolved wings, only invertebrate to fly
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Chordata

  • frogs snakes eagles humans
  • vertebral column or backbone
  • well developed brain enclosed in a cranum
    • fish- scales gills fins aquatic
    • amphibians- first land vertebrates, semi terrestrial, soft moist skin, eggs fertilised externally in water. young are aquatic with gills adults normally terrestial with simple lungs
    • reptiles- mainly terrestial with dry scaly skin, lungs and internal fertilisation of eggs with a shell and laid on land
    • birds- fly and have feathers, forelegs adapted as wings, lungs, and eggs with hard shell
    • mammals- skin with hair, born alive and fed on milk, lungs
      • marsupials- kangaroo- young born immaturely and develop in pouch
      • placentals- young born developed from womb, recieve nourishment via placenta before birth
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Common Ancestry

  • structures that may have different functions but are similar suggest common origin= homologous. pentadactyl limb of chordata adapted to the need of the vertebrate= human arm, bat wing, whale flipper, horse leg
  • possible to construct evolutionary trees
  • similar structures developed as a result of environmental conditions performing the same function= analogous bird and insect wings
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Genetic Evidence

  • new speices develops differences in the sequencing of nucleotide bases in DNA 
  • over time these differences accumilate as a result of evolution
  • DNA anaylsis confirms evolutionary relationships reducing the number of mistakes in classification due to convergent evolution
  • DNA hybridisation involves extraction and comparison of DNA of two species, sequence of bases compared and the more alike the more closely related
  • sequence of amino acids determined by DNA degree of similarity n amino acid sequence of the same protein in 2 species reflects the relationship
  • enables scientists to draw evolutionary tree for mammals
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Immunological Techniques

  • antibodies of one species respod to antigens on proteins in the blood of another
  • when they respond a precipitate is formed
  • more precipitate= more closely related
  • human serum injected into bunny>rabbit serum containing anti-human antibodies> added to other species serum
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