Evolution

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Evolution

• JP Slovak
• Texas A M University Commerce

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Early Observations

• Fossils of organisms that no longer exist
• fossilferous rock is stratified
• different organisms in different strata
• arrangement similar over different locales

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Misconceptions

• Individuals evolve into new forms
• evolution is simply the generation of new species
• species evolve to cope with the environment
• violates the 2nd law of thermodynamics

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Darwins postulates of natural selection

• There is heritable variation
• many offspring produced, not all survive
• some variants more likely to survive
• survivors pass on variations
• over long periods, favored characteristics prevail

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Mayrs inferences

• F1 potential exponential increase of
  populations
• F2 observed steady state of populations
• F3 limitation of resources
• I1 struggle for survival
• F4 uniqueness of the individual
• F5 heritability of much of individual variation
• I2 differential survival, i.e. natural
  selection
• I3 through many generations evolution

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Evidence

• Fossil record
• shows transitional forms
• constitutes millions of years
• will always be incomplete
• comparative anatomy
• convergent evolution
• divergent evolution
• analogous structures
• wings of birds and insects
• penguin and seal shapes
• homologous structures
• bat wing, dolphin fin, dog limb, human limbs
• vestigial structures
• molars in vampire bats, pelvic bones in whales
  and some snakes

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Evidence

• Biochemical and genetic analysis
• all cells have DNA
• life uses same amino acids to build proteins
• Evidence for natural selection
• artificial selection
• Dogs
• pesticide resistance
• antibiotic resistance
• types of selection
• stabilizing
• disruptive
• Directional
• sexual

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Other evolutionary concepts

• Gene pool
• variety
• mutation,crossing over, independent assortment,
  sexual reproduction
• gene flow
• genetic drift
• bottle necks
• founder effect
• inbreeding depression
• need reproductive isolation(stop gene flow) for
  speciation
• prezygotic and postzygotic

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