Principles of Evolution

The bigger picture

1. Definition
2. Examples of evolution in action
   • Drug-resistant bacteria
   • Dog breeds
3. A historical perspective
   • Cuvier (a paleontologist) & catastrophism
   • Lamarck: inheritance of acquired characteristics
   • Darwin: Descent with modification + natural selection

Evidence for evolution comes from:

1. Fossil record
2. Biogeography
3. Comparative anatomy
   • vestigial structures
   • homologous structures
   • analogous structures
4. Comparative embryology
5. Molecular biology

Mechanism of evolution

1. Populations have inherent, heritable variation
2. Populations produce more offspring than the environment can support
3. Individuals that are better adapted to the environment tend to survive longer and produce more offspring
   • "Survival of the fittest"
   • Natural selection
   • Artificial selection
4. Traits of the better-adapted individuals are passed on more frequently; populations adapt

Evolution works on populations

1. Evolution requires variation
   • How do you do natural selection on a population of clones?
2. Genetic variation arises by
   1. Mutation
   2. Recombination
3. Evolution acts on a population's gene pool
   1. The sum of all the genes & their alleles
   2. Calculating allele frequencies in a population
      • The Hardy-Weinberg equilibrium
   3. The ratio of alleles tends to stay the same under these conditions:
      • No mutation
      • No gene flow
      • Random mating
      • No genetic drift
      • No selection

Microevolution: changing the gene pool

1. Genetic drift
2. Bottleneck effect
3. Founder effect
4. Gene flow
5. Mutation
6. Natural selection
   • Diversifying
   • Stabilizing
   • Directional

The origin of species

1. Defining "species"
   • Biological species concept
2. Speciation and reproductive barriers
   • temporal isolation
   • behavioral isolation
   • habitat isolation
   • mechanical isolation
   • gametic isolation
   • Hybrid inviability
   • Hybrid sterility
3. Patterns of speciation
4. Mechanisms
   • Allopatric speciation
   • Sympatric speciation
5. Tempo of speciation
   • Gradualism
   • Punctuated equilibrium

Macroevolution

1. Biological novelty arises
   • Homeotic genes
   • Development
   • Exaptation
2. The changing earth
   • Oxygen
   • Climate changes
   • Mass extinctions
   • Continental drift
3. The diversity of life