1. Natural Selection Charles Darwin’s “suggestion” about how species change over time.

2. Evolution refers to changes in a SPECIES, not an individual

3. 4 Key Features to Charles Darwin’s theory of Natural Selection:  Variation  Competition  Fitness  Adaptation

4. Part 1: Variation  Individual members of a population have HERITABLE DIFFERENCES: small differences in the base sequence of their DNA  The differences that individuals have in their DNA gets passed on to their offspring  Happens because of –Random mutations –Sexual reproduction: combinations of gametes

5. Peppered moths

7. Part 2: Competition  The struggle for survival  The amount of resources in a habitat is fixed –Food, water, living space, mates, sunlight, minerals, shelter  MANY more individuals are produced during reproduction than will survive  There is a limit to how large a population can grow for a given area= carrying capacity

8. During spring, oak trees have FLOWERS, which produce pollen and egg cells. Pollen will fertilize the egg cells, producing the oak tree seed= the ACORN In one single year, an oak tree may produce up to 2000 acorns. MOST will not grow to be mature oak trees

9. What eats acorns?  Blue jays  Pigeons  Ducks  Mice  Squirrels  Chipmunks  Skunks  Raccoons  Deer  Bears  possums  Crows  Wild pigs  Moth larva  Weevil larva  NOT HORSES: acorns are toxic to them!

10. Mice  A single field mouse can have up to 17 litters of babies each year  Each litter can have up to 13 babies  That’s 221 baby mice per year from one female  MOST get eaten or die: –Hawks, owls, foxes, weasels, snakes

12. Sunflower  One sunflower plant can produce up to 1000 seeds  MOST get eaten!!

13. Part 3: Fitness  Genetically, some individuals have traits, either physical or behavioral, that make them better at surviving and reproducing  What determines which traits it is good to have??? –THE ENVIRONMENT

14. Part 4: Adaptation  Eventually, as more and more time goes by, and more and more individuals inherit a particular trait, ADAPTATION of the population occurs

17. Neck stretching

19. Natural selection?