Evolution

• Natural selection


  A process in which individuals with favorable inherited traits are more likely to survive and reproduce
• Descent with modification


  Darwin's perception of the unity of life, referring to the view that all organisms are related through descent from an ancestor that lived in the remote past
• Darwin's theory of evolution

  • Explains the unity of life, the diversity of life, and the match between organisms and their environment
• Darwin never used the word 'evolution' in the first edition of The Origin of Species
• Artificial selection


  The process where humans modify other species by selecting and breeding individuals with desired traits
• If some heritable traits are advantageous

  These will accumulate in a population over time, increasing the frequency of individuals with these traits
• Natural selection


  Increases the match between organisms and their environment over time
• Individuals do not evolve, populations evolve over time
• Natural selection can only increase or decrease heritable traits that vary in a population
• Adaptations vary with different environments
• Evidence for evolution


  • Direct observations, homology, the fossil record, biogeography
• Direct observations of evolutionary change

  • Soapberry bugs in Florida and Australia
  • Evolution of drug-resistant bacteria
• Homology


  Similarity resulting from common ancestry
• Homologous structures


  • Anatomical resemblances that represent variations on a structural theme present in a common ancestor
• Convergent evolution


  The evolution of similar, or analogous, features in distantly related groups
• Convergent evolution


  • Sugar glider and flying squirrel
• Fossils can document important transitions, such as the transition from land to sea in the ancestors of cetaceans
• Biogeography


  The scientific study of the geographic distribution of species, providing evidence of evolution
• Darwin's theory of evolution by natural selection integrates diverse areas of biological study and stimulates many new research questions
• Ongoing research adds to our understanding of evolution