1. Homologous structures
Structures on different organisms are homologous when they have similar base structures but have different functions.

2. Homologous structures
Human Arm
Bat Wing
Whale Flipper

4. Analogous Structures Similar functions but NOT structurally related.
Insects are arthropods and birds are vertebrates.
The wing of a bird and the wing of a butterfly are examples of analogous structures.

6. Comparative embryology

7. Vestigial Structures
A structure in an organism that has lost all or most of its original function

8. Transition fossils

9. The Panda's Thumb A classic example of evolution.
The giant panda is a bear that adapted to eating bamboo.

10. The panda’s opposable thumb
Giant pandas have a thumb pad on the hand
This thumb pad is used by the panda to grasp bamboo shoots
It uses its thumb to hold and manipulate the bamboo while eating

11. The Panda has not always had this opposable thumb
The Panda has not always had this opposable thumb. Fossil evidence shows that this has evolved over thousands of years.

12. Comparing bones.

14. Unrelated species evolve similar traits even though they live in different parts of the world, or at different times in Earth’s history

15. Analogous Structures = Convergent Evolution

16. Analogous Structures = Convergent Evolution

17. Analogous Structures = Convergent Evolution

18. Divergent Evolution: one species gives rise to many species

19. Divergent Evolution
One species gives rise to many species in response to the creation of new habitat or other ecological opportunity
Gives rise to homologous structures

20. Geographic isolation: prevents individuals of a species in different populations from mating

21. Geographic isolation prevents a mix of genes with the original species.
Example: Kodiak Brown Bears
This group of bears have evolved into a sub-species, that is different form all other grizzly bears.

22. An archipelago is a landform which consists of a chain or cluster of islands.

23. Adaptive radiation:
many species appear to be related to a single ancestral species.

26. Reproductive Isolation: prevents individuals from reproducing with each other
Prezygotic isolating mechanisms : prevent reproduction before fertilization
Postzygotic isolating mechanisms: prevent reproduction after fertilization

27. GRADUALISM
Living things change very slowly in small, gradual steps: GRADUALISM

28. PUNCTUATED EQUILIBRIUM
Sometimes species will remain the same for a long period of time and then change very quickly.
This is usually the result of some catastrophic disaster like an earthquake or volcano.

29. GALAPAGOS FINCHES

30. THE EVOLUTION OF BEAK SHAPE IN GALAPAGOS FINCHES
Darwin first thought about evolution while studying in the Galapagos
13 species of finches in the Galapagos islands
Islands are barriers that separate each group of the species- “Geographic Isolation”
size and shape of the beak has an important consequence for fitness. (What is Fitness?)

31. Darwin’s finches Medium Ground Finch Cactus Ground Finch
                      
Medium Ground Finch
Cactus Ground Finch
Medium Tree Finch
Warbler Finch

33. GALAPAGOS FINCHES Each species has a highly characteristic beak shape.
Darwin focused his study on the link between the shape of the beak, the food and the habitat of each species.
This research of his was to result in the theory of evolution and the 14 finches became "stars" in their own right.

38. The Case of the Galapagos Finches
All species of finch derive from the same original species.
The observation: despite their strong resemblance, each species of finch has a highly characteristic beak shape.
The evolutionary factors: geographic isolation, ecological environment, food sources, competition.