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What is evolution?. Evolution is…. Change over time Process by which modern organisms have descended from ancient organism THEORY!! Simply stated. Creationism. Theory that life on Earth was formed by a divine being. Science vs. Faith (not mutually exclusive). Hutton & Lyell.

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evolution is
Evolution is…
  • Change over time
  • Process by which modern organisms have descended from ancient organism
  • THEORY!!
  • Simply stated
  • Theory that life on Earth was formed by a divine being.
  • Science vs. Faith (not mutually exclusive)
hutton lyell
Hutton & Lyell
  • Concluded that the Earth is extremely old and that the processes that changed the Earth in the past are the same SLOW processes that operate in the present.
  • Reasoned that if the human population grew unchecked, there wouldn’t be enough living space and food for everyone.
  • Evolution by acquired traits
    • Organisms developed traits during their lifetime .
    • Give those traits (big muscles) to their offspring.
  • Example
    • In reaching higher leaves giraffes stretch their necks & give the acquired longer neck to offspring.
  • Not accepted as valid
darwin s view of evolution
Darwin’s view of Evolution

  • Father of modern evolution theory
    • Giraffes that alreadyhave long necks survive better.
    • Leave more offspring who inherit their long necks.
    • Believed in descent with modification.
    • Wrote a book: The Origin of Species
descent with modification
Descent with modification
  • All species—living and extinct– are descended from ancient common ancestors.
  • Over many generations, adaptations could cause successful species to evolve into new species making them better suited for their environment.
  • Examples: tiger’s claws; colors, like those that make camouflage or mimicry possible; or physiological functions, like the way a plant carries out photosynthesis.
survival of the fittest
“Survival of the fittest”
  • If you are better fit for your environment, you will survive.
  • You will reproduce.
  • Over time, population will be more like you.
  • Fitness: the ability to survive and reproduce.
voyage of the hms beagle
Voyage of the HMS Beagle
  • Stopped in Galapagos Islands
    • 500 miles off coast of Ecuador
darwin found many unique species
Darwin found…many unique species

Many of Darwin’s observations made him wonder… Why?

galapagos islands
Galapagos Islands
  • Example: Finches
    • 13 species of finches
    • Found on different islands
    • Beak size and shape varied
    • Ate different food
  • Finches had adapted to best obtain food in their environment.
natural selection
Natural Selection
  • Organisms with variations well suited to the environment survive and leave more offspring at a fast rate.
      • You have the genes to be successful in your environment or you don’t
  • Variety already exists, some varieties better fit to environment than others.
variety is the spice of life
Variety is the spice of life…
  • Variation: differences between members of the same species
  • Cause of variation = mutations
  • Variation is important to survival!
  • Example: Peppered Moth

Population A

Population B

Which population of hares has a better chance of survival as a species?

population b
Population B
  • Because it has more genetic variation than population A so there will be some individuals that are more fit if the environment were to change. Thus the species has a higher chance of survival.
take home message

Genetic variation increases a species’ chance of survival




artificial selection
Artificial Selection

The selective breeding of domesticated plants and animals by man. Provides variations that humans find useful.

Example: Dog breeds, & flowers