1. Summary from the last lectures
We have a reliable method for determining the age of rocks and fossils.
As a result we know:
The Earth and the solar system are 4.6 billion years old.
The oldest fossil organisms on Earth (bacteria) are 3.5 billion years old.
There is plenty of time for evolution
And the data do not support the hypothesis of Devine Creation of a 6,000 year old universe.

2. I believe this is the way the world is

3. Not this

4. Biogeography= the study of the distribution of organisms

5. From Wallace’s 1876 book
The Geographical Distribution of Animals

6. How do we explain these distribution patterns?
Proteaceae family

7. Flying squirrel distribution

8. Cichlid fish distribution

9. Wolverine distribution

10. How do organisms get to where they are found?
Created (evolved) there.
Active Immigration: under their own power (walking, swimming, flying).
Passive immigration carried by water, air, or land movement.
a. floating rafts of debris.
b. birds carrying seeds
c. insects carried by air currents
d. tectonic plates
e. humans carrying domestic animals & plants
invasive species

11. Test: Look at distribution patterns of organisms
Deduction (Prediction)
If the Hypothesis of Creationism is correct then there was a single Center of Creation .
And places with similar environments should have similar organisms
Test: Look at distribution patterns
of organisms

12. Creationist argument: Biblical Flood led to recolonization of the world when organisms disembarked from Noah’s Ark

13. The conventional explanation that species had been created with adaptations to their particular climate made no sense to Wallace because he knew similar climatic regions had very different animals in them.
Instead, he found that closely related species were found together even though they might be in different habitats.

14. If the Hypothesis of Creationism is correct then places with similar environments should have similar organisms.
Linnaeus (1701—1778) Father of Taxonomy
Different species live in different areas
Buffon (1707—1788) French Naturalist
Mammals of Africa & South America are different.
Humboldt (1769—1859)
Plants of Africa & South America are different.

15. No species are alike in Africa & South America
Lattreille (1762—1833) French zoologist
Insects are different in Africa & South America
Cuvier (1769—1832) French Paleontologist
Reptiles are different in Africa & South America
No species are alike in Africa & South America
even though their climates are similar.
They are in distinct Biogeographic Zones

16. Biogeographic Zones

17. There is no single center for Creation
Evaluation:
Data do not support the hypothesis of Devine Creation.
There is no single center for Creation

18. Test: Look at distribution patterns of organisms
Deduction (Prediction)
If the Hypothesis of Evolution is correct then related species should live near one another
Or distribution patterns should be explained by the geological record—barriers and diffusion
Test: Look at distribution patterns
of organisms

19. Distance between related species
Data:
Darwin in South America found species living close together are more similar than those living farther apart. X X
Similarity
Index X X X X X X X X X X
Distance between related species

20. Real Data for Gastropods (Snails Etc.)

21. Patterns of Distribution
Cosmopolitan Distribution (found almost everywhere in the world)
Brown rat

22. Patterns of Distribution
Continuous Distribution (found spread over a large range. E.g. starlings over Europe and N. America

23. Patterns of Distribution
Continuous zonal distribution (found throughout certain climatic zones.
E.g. moose spread throughout the Northern latitudes

24. Patterns of Distribution
Endemic Distribution (highly restricted to one area)
e.g. lemurs are restricted to Madagascar

25. Patterns of Distribution
Discontinuous (= Disjunct) Distribution
(found in a few separated areas)
e.g. bog turtle

26. The challenge is to explain how a once continuous population became discontinuous. Two answers:
Dispersal—population spreads out to distant places—flying, swimming, carried by wind or water or animals.
Vicariance—population gets split up by continental drift, glaciers, mountain building, rivers, and the intervening populations become extinct.

27. Patterns of Distribution
Scattered Distribution (small local populations)
e.g. Bighorn sheep

28. History matters How can we explain these distributions?
The creation model doesn’t help us.
But the evolution model plus the geological record should help us.
History matters

29. Abiotic Factors What are the factors that determine distribution?
1. Physical factors (e.g temperature, light, soil, fire, currents)
Abiotic Factors
2. Chemical factors (e.g. water, oxygen, salinity, pH, soil nutrients)
3. Biological factors (e.g. predators, parasites, disease, competition, food.)
4. Geographical & geological barriers to dispersal
(e.g. rivers, mountains, glaciers, oceans)

30. Patterns of interchange between biotic provinces.
Corridors = large areas where free migration can occur.
e.g. the animals of Western Europe , North China and North America are similar.

31. Land Bridges—Bering Strait
Asia
North America

32. Patterns of interchange between biotic provinces.
Filter bridge = an area of exchange between two areas that is restricted.
e.g. The Isthmus of Panama restricts movement between North and South America.
30—120 miles across
Formed 3 mya when South American continent collided with North America

33. Filter Land Bridges—Isthmus of Panama

34. Filter Land Bridges—Isthmus of Panama

35. Patterns of interchange between biotic provinces.
Sweepstakes Route = a route of exchange that is rare
Volcanic Islands are populated like this.
e.g. Galapagos Islands.
~600 miles from Ecuador
Animals and plants are like the mainland species

36. Island biogeography: Effect of distance from mainland
Bird species in the Lesser Antilles (D. Lack's data)

37. Species number and Island Area
Reptiles and Amphibians in the Caribbean Islands

38. So we can explain island biogeography on the basis of immigration into islands and extinction.
Immigration depends upon the distance from colonizing source (e.g. mainland). The more isolated the islands, the fewer species.
Extinction depends on the area available for speciation and niche specialization (The greater the island area, the more species can specialize and survive.)

39. Fragmentation of the environment producing islands
A big take a way message of this island study is that the smaller the island is, the fewer the species will survive.
As humans alter their environment with more houses, agricultural fields, parking lots and towns, they break up the environment into smaller and smaller parcels of land.
They fragment the environment into islands. And fewer and fewer species can exist.

40. How do we explain this? Mysterious case of Mesosaurus
Freshwater reptile living in lakes and steams.
One meter long.

41. Mysterious case of Mesosaurus.
Biogeography is forever seeking explanations of distributions using the principles of evolution, ecology, and geology.

42. Explained by continental drift !
Mysterious case of Mesosaurus
Explained by continental drift !

43. Continental
Drift

45. Continental
Drift

46. Plate Tectonics explains this

47. Flying squirrel distribution
Convergent evolution
explains this
Flying squirrel distribution

48. How do we explain this?

49. Wallace Line
A line separating the Asian and Australian biogeographic zones

50. The evidence from biogeography
Conclusion
There is no single center of distribution as you would expect with the Biblical Story of Creation.
The model of evolution can explain the patterns of distribution of organisms with the help of geology, ecology, evolution, and radiometric dating.
The evidence from biogeography
supports the model of
evoltuion

51. Next Time
Evidence from
Anatomy & Embryology