DARWIN'S THEORY OF EVOLUTION

DARWIN'S THEORY OF EVOLUTION

1. 5 THEORIES

   • NATURAL SELECTION
     • favourable variations would be preserved & unfavourable ones destroyed
     • variational theory of change
   • populational change
   • common descent
   • gradualism
   • characteristics of lineages of organisms change over time

2. main 2 components

   • pattern
     • divergent descent with modifications from common ancestors
       • explains diversity of life
   • process
     • natural selection - preferential survival & reproductive success

3. MICROEVOLUTION

   • mutation, recombination, natural selection & other processes operating with species
   • evolutionary patterns & processes evident within species as well as those leading to evolution of new species

4. MACROEVOLUTION

   • origin of new species & major long-term features of evolution
   • evolutionary patterns & process evident above level of species

5. GENETIC DRIFT

   • random changes in frequencies of different alleles in population
     • arise solely from chance sampling effects in their transmission from generation to generation, rather than from changes due to natural selection

6. EVIDENCE FOR EVOLUTION

   • hierarchical organisation of life
   • homology
   • embryological similarities
   • vestigial characters
   • convergence
   • sub-optimal design
   • geographic distributions
   • intermediate forms

7. COMPETITION

   • Pressure of competition favours use of different foods or habitats by different species
   • interaction within or between species resulting in one group consuming resources that could have been exploited by the other group, with negative consequences for fitness

8. PATTERNS OF EVOLUTION

   • common themes frequently inferred as associated with evolution of organisms, i.e. divergence, convergence, allometry, heterochrony, etc

9. STASIS

   • little or no evolutionary change within a lineage
     • major component of punctuated equilibrium model