Theory of evolution notes

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Theory of evolution notes

  1. 1. Theory of Evolution Natural Selection
  2. 2. Genetic variation is the driving force behindevolution. There are many ideas of why populationschange overtime. These changes may be due tomutation, movement of alleles betweenpopulations, interbreeding, isolation, and naturalselection
  3. 3. Theories of EvolutionA. Jean Baptist LamarckEvolution occurs due to inheritance of ACQUIRED TRAITS FROM A COMMON ANCESTOR, not from changes in the environmentIdea that variation in a population is created by experienceEx. Individuals passed on to offspring body and behavior changes acquired during life
  4. 4. What is wrong with this idea?
  5. 5. Theories of EvolutionB. Charles Darwin2 Major Theories:1. Descent with Modification: stated that ALLnew species were ALTERED DESCEDENTS ofOLDER ANCESTORS and arose from similargeographic locations
  6. 6. 2. Natural Selection: proposes that NATURE orenvironmental conditions DETERMINE andindividual’s CHARACTERISTICS, which in turnleads to EVOLVING population over time
  7. 7. 4 Mechanisms of Natural Selection
  8. 8. o GENE VARIATION EXISTS WITHIN A POPULATION Only if variation is GENETICALLY BASED will natural selection lead to evolution -MUTATIONS and RECOMBINATION of genes may produce beneficial changes and INCREASE gene variation within a population
  9. 9. o INDIVIDUALS WITH MORE SUCCESSFUL TRAITS WILL PASS TRAITS ON TO OFFSPRING -in turn, will increase the success of the population
  10. 10. o INDIVIDUALS MOST ADAPTED TO THE ENVIRONMENT WOULD GET THE BASIC RESOURCES FOR LIFE -ADAPTATION: individuals response to environmental pressures – may reduce competition within a population
  11. 11. o INDIVIDUALS THAT ARE MOST “FIT” HAVE GREATEST POTENTIAL TO REPRODUCE SUCCESSFULLY AND INCREASE POPULATION NUMBERS OVER TIME –”survival of the fittest”-FITNESS: reproductive success of one individuals genetic contribution to the next generation
  12. 12. Examples of “fitness”• Bacterial resistance to antibiotics
  13. 13. • Pesticide resistant insects
  14. 14. • Skin color - melanin
  15. 15. Summing Up Natural Selection

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