Darwinian Revolution — Unit 3
THE REVOLUTION COMPLETED

  • Mendel and the birth of genetics       Mendel*
    • Older ideas of "blending"
    • Mendel's experiments:
      • precautions
      • single-gene crosses: dominance, segregation
      • two-gene crosses: independent assortment
    • August Weismann
    • Rediscovery of Mendel in 1900 (Correns, Czermak, DeVries)
    • DeVries and mutations
    • Morgan's fruit flies
    • Sutton, Morgan, and the chromosomal theory of inheritance:
      • Linkage and mapping
      • Proof of crossing over (Creighton & McClintock; Stern )
  • Microevolution:   changes in gene frequencies within populations
    • Hardy-Weinberg equilibrium
    • Departures from Hardy-Weinberg:
      • mutations (unbalanced)
      • migrations
      • nonrandom mating (assortment, inbreeding)
      • genetic drift
      • natural selection
  • Natural selection demonstrated:       Selection*
  • Era of Controversy       Controversy*
    ...and birth of the Modern Synthesis      
    • Biometrical school & continuous variation
    • The rise of population genetics
    • Fisher (1930): The Genetical Theory of Natural Selection
    • Ecotypic variation (Clausen & al); L.R. Dice
    • Russian school (Chetverikov, Philipchenko, Dubinin, Dobzhansky)
    • Dobzhansky's Genetics and the Origin of Species
    • Ernst Mayr's Systematics and the Origin of Species (speciation theory)
    • Julian Huxley: The New Systematics;
      Evolution, the Modern Synthesis
  • Geographic variation within species       Geographic variation*
    • Geographic variation:
      • Importance of geographic variation
      • Occurence of (or absence of) geographic variation
      • Gene flow at ecotones
        example: mine entrances (Antonovics)
      • Altitudinal "races"
      • Insular & continental patterns
    • Clines, subspecies and species
      • Subspecies and polytypic species; pocket gophers and other examples
      • Clines
      • Hybrids
    • Species definitions: morphological, biological
      • biological species definition
      • reproductive isolation
      • reproductive isolating mechanisms (premating, postmating)
      • example: mallards and pintails
      • sibling species
  • Geographical speciation
    • What is speciation?
      • Phyletic transformation (anagenetic; no new RIM)
      • True speciation or splitting (cladogenetic; new RIM must evolve)
    • Geographic speciation.       Speciation*
      Speciation powerpoint         Longer powerpoint
      • Stages of geographic speciation.
      • Incomplete speciation:
        1. clines of reproductive isolation (e.g., Rana pipiens)
        2. clines with circular overlap (e.g., Parus major,   Ensatina)
        3. species in statu nascendi (e.g., Drosophila paulistorum)
      • Character displacement
      • Synchronic species problems
    • Alternative models of speciation.
      • SUDDEN speciation:
        • Genic (DeVries, Goldschmidt)
        • Chromosomal: aneuploidy? (no);   polyploidy (esp. in higher plants)
      • GRADUAL speciation:
        • Sympatric speciation (claimed in various cases)
        • Nonsympatric speciation (spectrum of possibilities):
          • Parapatric
          • Alloparapatric
          • Allopatric:
            • by crossing pre-existing barriers
            • with new barriers developing
            • by extinction of intervening populations in a cline
          • ?Symparapatric ("stasipatric")
      • allochronic species problems
    • Hybridism and polyploidy.
      • hybridism and its effects
      • speciation by polyploidy

  • Macroevolution         Macroevolution       Macroevolution* images
    • The geologic record. Lineages & trends.
      • Relative & absolute dating. Geologic time.
      • Fossils and stratigraphy
      • Lineages and trends:
        • primitive vs advanced
        • generalized vs specialized
        • anagenesis vs cladogenesis
      • Descent with modification
      • Family trees and classification
    • Directionalism versus opportunism.
      • Directionalism, teleology, finalism, and trends.
      • Branching evolution & opportunism; meaning of opportunism
      • Evidence for opportunism:
        • adaptive radiation
        • mosaic evolution
        • multiple solutions
        • vestigial organs,
        • imperfect adaptations
    • Adaptiveness of trends:
      Parallelism, convergence, homologies, variations in rates.
    • Evolutionary rates:
      Anagenetic & cladogenetic rates; evolutionary retrogression.
    • Example: horses
      • Evolutionary trends
      • Adaptive radiations
      • Variation in rates and direction
    • Dollo's law and historical laws in general
    • Phylogenetics and cladistics       Example: Animal Phyla
  • Highlights of vertebrate evolution
    • Vertebrate origins       Illustrations-- Vertebrates
    • Early jawless vertebrates
    • Origin of jaws; fish evolution
    • Amphibians and the transition to land
    • Reptiles and the amniote egg
    • Birds and flight
    • Mammals and homeothermy
  • Adaptive shifts and adaptive radiation;   Spandrels
  • Pleiotropy; deformities in domestic breeds
  • Further examples: insect evolution       Illustrations-- Insects
  • Origin of life--   Miller's experiment



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