Evidence for evolution

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    Khads <3

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    • What is evolution?
      + slow change in organisms and happens over long periods of time
      + all earth life evolved form simple life forms existed around 3 bya
      + happens natural selection
    • How does natural selection work?
      + species show variation
      + 'better adapted' ones survive
      + then have offspring with the 'better' phenotypes
    • What were Darwin's main ideas?
      + individuals organism in species show a wide range of variation for each characteristic
      + reproduction always gives more offspring than environment supports
      + pass on characteristics that enabled them to survive to the next generation when 'fittest' breed
      + they did not know alleles are passed on
    • What were the controversies of Darwin's work?
      + published work in 1859
      + challenged theory that God made all life on Earth
      + not much evidence
      + mechanism of natural selection (genes) not know until around 50 years later
    • Describe Wallace's work on speciation.
      + Wallace is best know for his work on warning colours (lets other animals know if they are poisonous or dangerous) in speciation
      + an example of speciation known as geographic isolation
    • How does speciation occur by geographic isolation?
      + population of same species become isolated from each other
      + environmental conditions differ e.g. food available
      + individuals most suited to environment in population are more likely to breed successfully
      + over time the pop. has more phenotypic differences
      + species - pop. becomes so genetically different they cannot breed internally and produce fertile offspring
    • What is palaeontology?
      study of fossils and fossil records
    • What do fossils show?
      + gradual change and form fossil record
      + oldest fossils are simplest life forms and more recent are more complex organisms
      + sequence of discovery corresponds to ecological links
      + investigate differences between extinct and extant (living) species
    • What are fossils?
      + remains of ancient organisms from millions of years ago in rocks
      + may form from parts of organisms not yet decayed or conditions for decay not present (e.g. oxygen and water)
      + preserved traces of organisms -> footprints, burrows and rootlet traces (plant traces)
      + when parts of organisms are replaced by mineral as they decay
    • Why are there incomplete fossil records?
      + early life forms are soft bodied and few traces remain
      + organisms mainly not fossilised due to rare conditions for fossilisation needed
      + still discovering fossils
      + traces destroyed by geological activity e.g. earthquakes, volcanic eruptions
    • How can fossils be used to observe DNA?
      the animals not decayed to form fossils can have DNA extracted and compare to modern organisms
    • What can fossils show?
      + can show how much an organism change since life developed
      + radioisotopes (radioactive isotopes of an element) can date fossils
      + very few complete fossils records for few animals
      + helps scientists to predict ecology, climate and environment years ago
      + shows some animals not change very much e.g. sharks due to similar environment
    • How can comparative anatomy be used to prove evolution?
      + similarities and differences in anatomy
      + use of homologous structures - superficially different (may have different functions) in diff organisms but same underlying structure e.g. pentadactyl limb
      + provide evidence for divergent evolution = two groups of same species evolve different traits within groups due to different selection pressures
    • How can molecular evidence be used to prove evolution?
      + some important molecules highly conserved (almost unchanged) among species
      + slight changes help identify evolutionary links
      + gradual changes in DNA base sequence cause evolution
      + organisms diverged away from each other have more similar DNA sequences
    • What is neutral evolution?
      when there is a neutral base pair substitutions
      neutral mutations are not beneficial or detrimental to the activity of the organism to survive and reproduce
    • How can mutations cause biomolecular differences?
      + change DNA sequence affect amino acid sequence
      + organisms more recently diverged have more similarities in amino acid of cytochrome c ( one of the main mitochondrial proteins involved in aerobic respiration and PCD) as less time is passed
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