1. (Survival of the Fittest)
DARWIN’S THEORY of
NATURAL
SELECTION
(Survival of the Fittest)

2. HOW DOES NATURAL SELECTION LEAD TO EVOLUTION?
In this section you will want to find the answers for:
HOW DID DARWIN EXPLAIN THE DIFFERENCES BETWEEN SPECIES ON THE GALAPAGOS ISLANDS AND ON MAINLAND SOUTH AMERICA?
HOW DOES NATURAL SELECTION LEAD TO EVOLUTION?
HOW DO NEW SPECIES FORM?

4. In 1831, Charles Darwin set sail on the HMS Beagle for a 5 year trip around the world
Darwin collected and studied numerous marine organisms during this famous voyage...

5. Observations he made on the Beagle expedition also provided him with the ideas that he later used to formulate his theory of evolution and natural selection.

6. Group of similar organisms that can mate and produce offspring
VOCABULARY
SCIENTIFIC THEORY:
a well tested concept (idea) that explains a wide range of observations
What is the difference between an idea, theory and fact?
SPECIES:
Group of similar organisms that can mate and produce offspring

7. DARWIN’S THEORY:
Species gradually change over many generations and become better adapted to new conditions

9. THE GALAPOGOS ISALNDS ARE A GROUP OF VOLCANIC ISLANDS

10. HOW DID DARWIN THINK PLANTS...

11. ...AND ANIMALS ORIGINALLY CAME TO GALAPAGOS ISLAND?

12. Ancestors of today’s plants & animals on the islands were brought from the mainland by wind, currents, or on floating debris...

13. FROM MAINLAND RELATIVES DUE TO RESOURCES AVAILABLE.
ONCE THEY REACHED ILSANDS, THEY REPRODUCED & OFFSPRING BECAME DIFFERENT
FROM MAINLAND RELATIVES DUE TO RESOURCES AVAILABLE.
Island Turtles
Mainland Turtle

14. THIS BRINGS US TO DARWIN’S THEORY OF NATURAL SELECTION

15. Natural Selection
Individuals that are better adapted to their environment are more likely to survive.

16. SURVIVAL OF THE FITTEST
WHAT ARE FACTORS THAT AFFECT SURVIVAL?
Differences in species (variations)
Over production of same species
Competition for resources

17. HOW DOES THIS APPLY TO THE GALAPAGOS ISLANDS?
SO….
HOW DOES THIS APPLY TO THE GALAPAGOS ISLANDS?

18. Organisms that were on the Islands first had NO competition for resources (food, shelter, H2O) because no other species was there.

19. Darwin studied finches found on these islands
Darwin studied finches found on these islands. This played an important role in his recognition of the evolutionary process.

20. by studying the finches - Darwin
showed how species are related to other species

21. over long periods of time natural selection can lead to evolution.
...And
over long periods of time natural selection can lead to evolution.
VARIATIONS IN ORGANISMS GRADUALLY ACCUMULATE WHILE UNFAVORABLE ONES DISAPPEAR.
HOW?

22. As you can see in the next photos, Darwin's finches share similar size color, and habits - the difference is size and shape of their beak.

23. The
F I N C H E S

24. WARBLER FINCHES

31. Lava Finch Galapagos Volcanoes

33. WHAT ARE SOME OTHER WAYS NEW SPECIES COULD HAVE FORMED?
CONTINENTAL
DRIFT

34. SEPARATION by:
RIVERS

35. SURVIVAL of the FITTEST

36. How is each organism suited to play a certain role in a certain habitat?
ADAPTATIONS:
inherited features that let organisms survive & produce young

38. Camouflage:
Adaptations that allow organisms to blend in w/environment.

39. What’s right w/these pics?

42. What’s the problem here?

43. What’s wrong w/this pic?

44. ANOTHER ADAPTATION SEEN IN ANIMALS AND PLANTS:
MIMICRY

45. KING SNAKE

46. CORAL SNAKE

47. WHICH IS WHICH?
CORAL KING

49. WHAT MAKES AN IDEA A THEORY?
CRITICAL THINKING
WHAT MAKES AN IDEA A THEORY?
HOW IS A THEORY DIFFERENT FROM A FACT?
UPON WHAT FACTS DID DARWIN BASE HIS THEORY OF EVOLUTION?