Theory of evolution notes
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Natural selection is the driving force behind evolution. According to Charles Darwin's theory of natural selection: 1) There is genetic variation within populations. Traits that increase reproductive success will be passed on more frequently. 2) Individuals with traits better suited to the environment will have greater access to resources and be more likely to reproduce. 3) Over time, individuals with traits that increase reproductive success will comprise a greater proportion of the population, leading populations to evolve.
Theory of evolution notes
- 1. Theory of Evolution Natural Selection
- 2. Genetic variation is the driving force behind evolution. There are many ideas of why populations change overtime. These changes may be due to mutation, movement of alleles between populations, interbreeding, isolation, and natural selection
- 3. Theories of Evolution A. 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 Evolution B. Charles Darwin 2 Major Theories: 1. Descent with Modification: stated that ALL new species were ALTERED DESCEDENTS of OLDER ANCESTORS and arose from similar geographic locations
- 6. 2. Natural Selection: proposes that NATURE or environmental conditions DETERMINE and individual’s CHARACTERISTICS, which in turn leads 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