BY2:1 Biodiversity

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  • BY2:1
    • Biodiversity
      • 'A measure of the number of species in a given area'
      • Number of species per square km increases as one moves form the poles to the tropics
      • Important because species are linked within ecosystems
      • If one species increases or decreases in number, it will effect other species within the ecosystem
    • Species
      • 'A group of organisms that share a large number of common characteristics and can interbreed and produce fertile offspring'
    • Species Diversity
      • 'The number of different species and the proportion of each species in a  given area'
    • Biodiversity Hotspots
      • 25 hot spots of biodiversity around the world
      • Tropical rainforests and coral reefs are the most biodiverse places in the world
    • Extinction
      • The fossil record shows that most species are now extinct
      • Natural process that has been occuring since life began, it is the current rate of extinction that is creating the biodiversity crisis
      • 'Loss of species'
      • Reason: Loss of habitat due to deforestation
      • Reason: Loss of habitat due to pollution
      • Reason: Loss of habitat due to drainage of wetlands
      • Reason: Over hunting by humans
      • Reason: Competition from the introduction of an alien species
    • Evolution
      • 'The process by which new species are formed from pre-existing ones over a period of time'
      • Gives rise to variation
      • Involves a change in an organisms genotype (genes) and phenotype (physical characteristics)
      • SInce the mess extinctions, the fossil records show that biodiversity has increased and new species have radiated out from a common ancestor
      • Natural selection brings about the evolution of species from a common ancestor
      • Evolutionary history shows there have been 5 mass extinctions: bottlenecks in biodiversity
    • Adaptive Radiation
      • 'The emergence of a new species from a common ancestor introduced to an environment'
      • It occurs: Following mass extinctions and when a species moves to a new area with lots of ecological opportunities
      • Darwins FInches
        • In 1832, Darwin travelled to South America studying organisms there, including 14 varieties of finches
          • Darwin noticed that individual finches differed from one island to the next, the main difference being the size and shape of their beaks, relating to the different foods available on the island
            • It seemed that on each island, the characteristics that best suited a finch to it's environment were inherited by the offspring. Darwin suggested that the different finches had developed from one common ancestor and the type of beak had developed over time and become specialised for one food source.
    • Naural Selection
      • Darwin's observations of variation within a population lead to the development of natural selection and the belief it drives evolution of new species
      • Basic principle of natural selection is that organisms better suited to their environment will survive are reproduce to produce successful offspring
    • Taxonomy
      • Classification:The arrangement of organisms into groups based on shared features
      • 'The branch of biology concerned with naming and classifying the diverse forms of life'
      • Linnaean Taxonomy
        • Carl Linnaeus was the first scientist to introduce a formal system of taxonomy
          • System with two main characteristics: Uses hierarchy approach and binomial system
            • Binomial Nomenclature
              • The last two taxa are used to give the organism it's name
                • Biological name is always written in italics when printed, underlined or handwritten
                • Binomial System used to avoid confusion of local common names and languages
            • Hierarchy involves: a larger group of organisms sub-divided into smaller groups
              • Members of a group sharing features unique to that group and no overlap between groups
              • 7 catagories within this system, each successive group from kingdom to species containing less organisms and being more closely related
              • Kingdom Phylum   Class      Order       Family Genus    Species
              • Animalia Chordata Mammalio Primate Hominidae Homo Sapien
    • Phylogenetic Classification
      • Biological classification of organisms
        • Shared Characteristics
          • Morphology and the presence of homologous structures
            • e.g Pentadactyl limb in vertebrates
            • Dangers of using morphology to classify organisms
              • Some physical characteristics can appear the same on the surface and therefore suggest organisms are related but on furthur investgation the structures are quite different
              • Homologous Structures
                • May not have same function
                • Same fundamental structure
                • Evolved from a common ancestor
              • Analogous Structures
                • Differ in fundamental structure
                • Have same function
                • Superficial resembelance
          • Biochemical make up
            • e.g. DNA fingerprinting and amino acid sequences of common proteins are used to estimate relatedness between species
            • To overcome the problems that can be caused by classification by morphology alone
            • Compare the sequence of amino acids in common proteins
            • Compare the sequence of bases in the DNA of genes (DNA fingerprinting)
      • Evolutionary Relationships
        • Fossil records and biochemical analysis are used to work out the evolutionary relationships between organisms
          • Fossil: 'preserved remains of dead plants and animals'
        • It is believed that all organisms come from a commom ancestor
        • Species with many common characteristics are closley related and share a recent common ancestor
      • Phylogenetic tree
        • Shows the ancestry of groups or points of divergence
        • Key to phylogenetic classification is looking for the sorts of common features that must be due to common ancestors and not due to environmental presures
        • The closer the branches of the tree, the more recent the points of divergence of the species and the closer the evolutionary relationships

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