GEN BIO SA2 REVIEWER

• Significant Individuals in the History of Evolutionary Thought

  • Aristotle
  • Buffon
  • Hutton
  • Cuvier
  • Lamarck
  • Lyell
  • Darwin & Wallace
  • Georges-Louis LECLERC
  • Carolus LINNAEUS
  • Erasmus DARWIN
  • Georges CUVIERL
  • James HUTTON
  • Charles LYELL
  • Jean LAMARCK
  • Thomas MALTHUS
  • Charles DARWIN
• Aristotle


  • Individuals in a species are basically identical and species are unchanging
• Buffon


  • Species change as they spread from their original location
• Hutton


  • Changes in nature are gradual; uniformitarianism
• Cuvier


  • Species reappear after catastrophes; fossils represent extinctions
• Lamarck


  • New species come from existing species through environmental forces
• Lyell


  • All changes in nature are gradual; renewed uniformitarianism
• Darwin & Wallace


  • Individuals in a population are different; species arise through the process of natural selection
• Georges-Louis LECLERC


  44 volume natural history series describing plants and animals that provided evidence of evolution
• Carolus LINNAEUS


  • Developed binomial nomenclature and classification system for living organisms
  • Believed in scala naturae (great chain of being) and fixity of species

  
• Erasmus DARWIN


  • Formulated one of the first formal theories on evolution in zoonomia
  • Based on conclusions on change in animals during development, animal breeding by humans and presence of vestigial structures
• Georges CUVIERL


  • Established sciences of comparative anatomy and paleontology
  • Developed theory of catastrophes where animal and plant species are destroyed by these and new species evolve after that
• James HUTTON & Charles LYELL

  Developed the concept of uniformitarianism: earth's landscapes like mountains and oceans formed over long periods of time through gradual processes
• Jean LAMARCK


  • Believed that acquired characteristics are inheritable
  • Proposed 2 principles: (1) law of use and disuse and (2) inheritance of acquired characteristics
  • His theory explains that environment can produce physical changes in an organism during its lifetime which can be inherited in the next generation
• Thomas MALTHUS


  "An Essay on the Principle of Population" proposing that the size of human populations is limited by available resources that can support it
• Charles DARWIN


  • Theory of evolution by natural selection became the foundation of modern evolutionary studies
  • Observed the world in his journey of the HMS Beagle where his theories originated in observations made on the Galapagos Islands
• Observations made by Charles Darwin

  • Geology and Fossils
  • Biogeographical Observations
  • Publication of "On the Origin of Species"
  • Logic of Natural Selection
• Genetic Variation


  No 2 individuals are exactly alike, some variation is heritable
• Limited resources


  Every habitat has limited supplies of resources required for survival
• Overproduction of offspring


  More individuals are born than survive to reproduce
• Struggle for existence


  Individuals compete for limited resources to survive
• Unequal reproductive success (natural selection)


  Inherited traits of some individuals make them more likely to obtain resources, survive, and reproduce
• Descent with modification


  A population's characteristics can change by natural selection, giving rise to new species
• Modern Synthesis Theory of Evolution unifies ideas about DNA, mutations, inheritance and natural selection
• Gene pool


  • Combination of all genes (including alleles) present in a reproducing population or species
  • Large gene pool has extensive genomic diversity and is better able to withstand environmental challenges
• Allele Frequency


  • Relative frequency of an allele at a particular locus in a population
  • Fraction of all chromosomes in population that carry that allele over the total population or sample size

  
• Hardy-Weinberg Equilibrium


  • Population in which allele frequencies do not change over time, stable and non evolving state
  • Factors disrupting genetic equilibrium: Mutations, Natural selection, Non random Mating, Genetic Drift, Gene flow

  
• Evolution is a change in allele frequencies in a population over generation but a population in HWE is not evolving

  
• Microevolution


  Evolutionary change within populations
• Causes of Microevolution


  • Natural Selection
  • Mutation
  • Gene Flow
  • Genetic Drift
  • Non-Random Mating

  
• Directional Selection


  Extreme phenotype is favored and the frequency distribution curve shifts in that direction
• Disruptive Selection


  2 or more extreme phenotypes are favored over any intermediate phenotype
• Stabilizing Selection


  Intermediate phenotype is favored
• Sexual Selection


  • Adaptive changes in males and females that lead to an increased ability to secure a mate
  • Intrasexual Selection: members of 1 sex compete among themselves for access to opposite sex, strongest males are most likely to pass their alleles
  • Intersexual Selection: members of 1 sex choose their mates from among multiple individuals of the opposite sex, brightest males get more opportunities to mate
• Macroevolution


  • Patterns and processes associated with evolutionary change at and above the species level
  • Results in speciation or the formation of new species occurs when members of a population can no longer interbreed with the rest of the group
• Patterns of Macroevolution


  • Divergent evolution
  • Convergent Evolution
  • Parallel Evolution
  • Coevolution
• Reproductive Isolating Mechanisms


  • Prezygotic Isolation
  • Postzygotic Isolation
• Prezygotic Isolation


  • Occurs before the formation of a zygote
  • Prevent reproductive attempts and make it unlikely that fertilization will be successful if mating is attempted
• Types of Prezygotic Isolation

  • Habitat Isolation
  • Temporal Isolation
  • Behavioral Isolation
  • Mechanical Isolation
  • Gametic Isolation
• Postzygotic Isolation


  Prevent hybrid offspring from developing or breeding even if reproduction attempts are successful