Topic 7

• Theory of evolution

  The basis of modern biology
• Evidence for evolution

  • Drawn from biogeography
  • Fossil record
  • DNA/protein arrangements
  • Homology
  • Embryology
• Biogeography


  1. Studying the distribution of species across space and time

  2. Matching geographic patterns of species to their geological history

  3. Indicating relationship between common ancestry and environmental adaptation
• Australian marsupials and other placental mammals


  • Exemplify how evolution has shaped life in response to different ecosystems
• The evidence for evolution is compelling and extensive
• Biogeography


  The study of how and why organisms live where they do
• Geographic distribution of organisms

  Follows patterns best explained by evolution and movement of tectonic plates
• Broad groupings of organisms

  • Distributed worldwide if evolved before Pangaea breakup
  • Appear uniquely in smaller regions if evolved after Pangaea breakup
• Galápagos finches


  • Descended from one bird that arrived on the islands from South America
  • Evolved into many finch species, each adapted for a different type of food
• Adaptive radiation


  The process by which a single species evolves into many new species to fill available ecological niches
• Fossil record

  • Records the advancement of less complex to more complex living beings
  • Uncovers transitional shapes that give concrete evidence of developmental moves
• Fossils provide solid evidence that organisms from the past are not the same as those found today, and fossils show a progression of evolution
• Evolution of humans and horses

  • Highly detailed fossil records showing the evolution of form over millions of years
• Comparative genomics

  Reveals shared genetic codes and sequences, underscoring the relatedness of species
• Homology

  Similarity in anatomical structures or genetic sequences between different species, indicating shared developmental origins
• Pentadactyl appendage in different vertebrates

  • Homologous structures with shared developmental beginnings
• Leaves of plants

  • Modified through evolution to have different shapes and serve different functions
• Embryology


  The study of the development of the anatomy of an organism to its adult form
• Similarities in embryonic development among diverse species reveal shared genetic pathways
• Homologous structures


  Structures that share the same overall construction despite changes in shape and size over time, evidence of descent from a common ancestor
• Vestigial structures


  Unused structures without function, residual parts from a past ancestor
• The evidence supporting evolution draws from biogeography, the fossil record, DNA/protein arrangements, homology, and embryology
• The unity of life, woven through shared parentage and slow alterations over time, stands as a confirmation of the explanatory power and observational strength of the theory of evolution
• Charles Darwin first comprehensively assembled the evidence for evolution, convincing his scientific contemporaries of the fact of descent with modification
• Since Darwin, genetics has joined the synthesis, and evolution in natural populations has proven to occur sufficiently rapidly that it can be observed on human timescales
• The most direct evidence of evolution comes from the fossil record, in which the dynamic changes of life over time are recorded, including many transitions between major taxa
• A host of phenomena in comparative biology that otherwise appear inexplicable or anomalous are readily explained under the hypothesis of descent with modification
• Direct observation of natural and artificial populations shows the process of evolutionary change in action
• Together, these sources of evidence lead to a "consilience of inductions" that makes the fact of evolution one of the most securely established generalizations in science