1. The History and Development of Evolutionary Theory

2. Fossil Fraud In The News

3. Charles Darwin Medical Student Later attended Cambridge
Interest in medicine waned
Interest in natural history grew
Later attended Cambridge
Accepted position as naturalist for voyage of discovery on H.M.S. Beagle

4. Voyage of the Beagle

5. Darwin’s Voyage Initially convinced that species did not change
Observed many phenomenon
Fossils of extinct animals
Similar geographic areas had different species
Began to change his ideas about species change

6. Species
Group of interbreeding natural populations that are reproductively isolated from other such groups

7. Fossil Relatives

8. Similar Species, Different Places
Galapagos finch
Mainland finch

9. Darwin’s Realizations
Organisms of past & present are related
Factors play a role in development of diversity
Members of a species change slightly when geographically isolated
Organisms from islands often resemble those on a nearby mainland

10. Change in Earth Over Time
Charles Lyell (1830s)
Uniformitarianism
Today’s Earth results from gradual change
Challenged catastrophism
Fossils are similar, but different than living organisms
Evidence that change has occurred

11. Artificial Selection A clue for Darwin
Breeder can select for desired characters
Depends upon natural variation

12. Choosing Parents Changes Species

13. Population Growth has Limits
Thomas Malthus ( )
Populations can increase exponentially
Food supplies increase arithmetically
Factors limit population growth

14. Darwin’s Associations
Processes of artificial breeding
Factors limiting survival
Reproduction within natural populations
Environmental factors affect natural populations
Traits could be naturally selected

15. Darwin’s Conclusion
Individuals with attributes well suited to their environment are more likely to survive and pass those attributes to offspring

16. Adaptations Naturally occurring heritable traits
Favorable to survival and reproduction

17. Natural Selection
Process by which organisms having adaptive traits reproduce in greater numbers than those without such traits
Changes the species with time

18. Evolution by Natural Selection
Populations change over time
Change is driven by natural selection for best adapted individuals
Descent with modification from common ancestors

19. Darwin’s Finches Example of natural selection
Found on Galapagos Islands
Show change from common ancestor
Beaks are adaptations to food source
All are thought to be from a single common ancestor from the mainland

21. Adaptive Radiation
Population changes as it occupies different habitats within a region

22. Darwin’s Finches still Evolving
Rosemary & Peter Grant’s work
Galapagos island of Daphne Major
Documented evolution of beak size
Observing evolution in progress

23. Evolution Before Darwin
Darwin was not the first to observe evolution
Jean-Baptiste Lamark ( )
Inheritance by acquired characteristics
Inaccurately concluded change was due to need
Correctly observed that species change, incorrectly defined process of change

24. Alfred Russel Wallace Independently discovered natural selection
Influenced by same factors as Darwin
Naturalist working in Malaysia
Jointly presented theory with Darwin

25. Darwin’s Book On the Origin of Species by Means of Natural Selection
Published in 1859
Started many debates
Evidence continues overwhelming support

26. Evidence for Evolution
Fossils
Comparative anatomy
Comparative embryology
Molecular evidence

27. Fossils Preserved evidence of past life Soft parts are rare as fossils
Remains
Impressions
Traces
Soft parts are rare
as fossils

28. Fossil Record Rock layers provide an ordered record
New layers deposited on top of old layers
Provides for relative dating

29. Fossil Evidence Past living forms can be observed
Change through time can be documented

31. Fossil Dating Direct dating methods are available
Example: carbon dating
Gives accurate time relationship
Shows that time existed for organisms to develop from ancestral forms

32. Age of Earth
Until Darwin’s time most thought earth was 6,000 to 10,000 years old
Earth is know to be about 4.6 billion years old

33. Comparative Anatomy
Related organisms have same structure as common ancestor
Modifications reflect adaptations
Homologous structures
Same embryological origin
Same underlying anatomy, different function

35. Vestigial Structures Homologous structure no longer useful
Diminished over time
Example: snake’s vestigial leg bone

36. Analogous Structures Structures that appear similar
Found in organisms that do not share embryological origin or underlying anatomy

37. Convergent Evolution Creates analogous structures
Change in organisms with different ancestors
Structures appear similar

38. Comparative Embryology
Similarities among embryos point to common ancestors
Similar genes with new instructions over time

39. Molecular Evidence All life has DNA as hereditary material
Species with similar DNA are closely related

40. Phylogeny Evolutionary history of an organism Phylogenetic tree
Depiction of phylogeny
Pattern of evolutionary
relationships
Ernst Haeckel first used
tree depiction

41. Taxon
Named group of organisms

42. Phylogenetic Trees Tips represent taxa
Branches represent evolution over time
Nodes represent common ancestors

44. Methods to Construct Phylogeny
Comparative characters
Genetic information

45. End chapter 15