What is evolution?

1. What is evolution? • Change • Evidences • Mutation • Heredity • Time • DNA • Environment • Adaptations

2. What evolution is NOT • Is not a faith, ideas are derived from evidences • Does not negate the existence of a higher power • Does not imply that humans came from apes • Does not imply that organisms change to their environment but that the environment selects certain varieties of organisms to live.

3. So WHAT is evolution? The process of biological change by which descendants come to differ from their ancestors.

4. So, it is JUST a theory… A theory is a concept that is supported by a great deal of evidence and experimentation and has not been disproved.

5. The comprehensive definition… Evolution is hereditary (DNA) changes (mutations) in groups (not individuals) of organisms over time (gradual) in response to the environment.

6. So, who developed a theory to explain how evolution or change over time occurs in living things?

7. Charles Darwin

8. Darwin • A nonacademic student but a curious naturalist • Hired at 22 as a naturalist on the ship HMS Beagle for a 5 year journey • Collected many specimens • Read Geology books about earth changes • Questioned the relatedness of species rather than individual creation of species

9. The last data Darwin needed for a theory of evolution lay in the Galápagos Islands off the west coast of South America. He found its plant and animal life had grown apart from that in South America. Its evolution had been isolated.

10. Darwin’s Observations • Let’s consider 4 observations • Tortoises • Rhea, Emu and Ostrich • Finches • Fossils of animals

11. Darwin’s Observations Galapagos Tortoises Live in different environments on different islands. Domed tortoise- live in Areas with low vegetation Saddle-backed tortoises can stretch their necks to reach tall vegetation.

12. Emus - Australia Rheas - South America Ostriches - Africa Why were the similarities of these birds surprising to Darwin?

13. Darwin’s finches

14. Finch beak adaptations

15. Why are finches in the Galapagos Islands similar to those in S. America?

16. Darwin observed fossils of huge animals such as Glyptodon, a giant armadillo.

17. Sloths Natural selection over time. Present day

18. Skeleton of giant sloth in a museum

19. Species can vary • Locally • Globally • Over time

20. What is a species anyway? • For a group to be in the same species, they must: • Reproduce • Have fertile offspring

21. All dogs are in the same species. How many of these were artificially selected?

22. Was Darwin the first one to think about the concept of a changing group of organisms? • NO • Darwin was influenced by several naturalists and geologists of the time

23. In the early 1800’s, prevailing thoughts about nature including living organisms and the earth was • The idea of “fixed and nonchangeable” organisms • The age of the earth was 6000 years old

24. But…People were challenging these ideas!

25. The times were a-changin’ • 18th and 19th centuries were periods of great social, political, and scientific change • 1776 – Declaration of Independence • 1789 – French Revolution • 1848 – Marx and Engels Communist Manifesto • 1866 – Mendel publishes research on genetics

26. Erasmus Darwin, Charles’ grandfather, was a physician. He had the idea of a changing group of organisms instead of fixed organisms. 1770 In his Zoonomia and Temple of Nature, he offered a speculative theory of evolution that was widely denounced for religious and political reasons

27. Carolus Linnaeus • Proposed a system of classification based on similarities • New organisms could arise by hybridization He grouped organisms into categories based on what they looked like.

28. Lamarck 1774-1829 • proposed that organisms change in response to their environment

29. However, he was incorrect in that… His theory was based on the • Inheritance of acquired characteristics • Use and disuse of parts

31. Influence of geologists • Earth is millions of years old • Processes that change the earth today (volcanism, erosion, etc) are the same ones that changed the earth in the past

32. James Hutton Proposed that earth was very old and changes in the earth were gradual (gradualism)

33. Charles Lyell • Argued that the processes that changed Earth in the past are the same ones that change the earth today – uniformitarianism • This made Darwin think that life forms could change too.

34. Thomas Malthus • A sociologist that argued if the human population continued to grow unchecked, it would run out of living space and food. • Struggle for existence

35. The importance of variation • Artificial – man selects which organisms to breed (selective breeding) • Natural – nature selects which organisms to breed

36. Darwin based his work on breeding animals and plants. The process in which humans change species by selective breeding is called artificial selection. Darwin also noticed that in order for selection to occur, the trait must be inherited.

37. Darwin studied artificial selection (man selected) traits and applied this to his theory of natural selection Artificial Selection I think I like this one!

38. What two conditions must be true for a group of animals to be considered the same species? • They must reproduce. • They must have fertile offspring.

39. Variations – difference in physical traits of an individual from those of other individuals in the group Variations among different species INTERSPECIFIC

40. Variations among members of the same species INTRASPECIFIC variation

41. Adaptation-a feature that allows an organism to better survive in its environment • Which finch eats large, hard-shelled nuts?

42. Bird Beak Adaptations

43. How does evolution work? The mechanism for evolution as determined by Darwin is natural selection.

44. What are the four components of natural selection? Presence of genetic variation Overproduction of offspring Struggle for existence Differential survival (survival of the fittest) and reproduction based on adaptations

45. Theory of Natural Selection 4 Principles: 1. variation- heritable differences, or variations that exist in every population 2. overproduction- increases the competition for resources 3. adaptation 4. descent with modification- adaptations that are beneficial increase with the next generation

46. What determines an individual hummingbird’s length?

47. What do the researchers use to determine the evolutionary history of the hummingbirds? DNA Sequences

48. What Darwin called evolution…..Descent with modification A heritable trait becomes common in a population causes branches from common ancestors

49. Darwin’s Tree of Life All organisms have a common ancestor (the trunk) but due to the environment, organisms change (become the branches). He called this “Descent with Modification”.

50. Evolution as Envisioned by Darwin The Origin of Species (1859) Ch.IV Divergence of Character Notebook B, ~July, 1837