Theory of evolution notes

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  • 1. Theory of Evolution Natural Selection
  • 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. 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. What is wrong with this idea?
  • 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. 2. Natural Selection: proposes that NATURE orenvironmental conditions DETERMINE andindividual’s CHARACTERISTICS, which in turnleads to EVOLVING population over time
  • 7. 4 Mechanisms of Natural Selection
  • 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. o INDIVIDUALS WITH MORE SUCCESSFUL TRAITS WILL PASS TRAITS ON TO OFFSPRING -in turn, will increase the success of the population
  • 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. 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. Examples of “fitness”• Bacterial resistance to antibiotics
  • 13. • Pesticide resistant insects
  • 14. • Skin color - melanin
  • 15. Summing Up Natural Selection