1. Evidence for evolution
Darwin’s theories

2. Darwin – Evolution by Natural selection
Survival of the fittest.
The ones that are most “fit” are adapted to survive, have more offspring and pass on the traits to those offspring

3. Darwin or Lamarck?

4. “Origin of Species” 2 main points of Darwin
1) Descent with modification
2) Natural selection – A differential success in reproduction caused by an interaction between the environment and the phenotypes of a population

5. Darwin’s big adventure!
He sailed around the world

6. He sailed on the Beagle
No, Not that beagle!!!!!!!

7. HMS Beagle
This one

8. Darwin observed
There was a change in diversity as he sailed. There was more diversity close to equator which became less as he sailed toward poles

9. Galapagos islands

10. He studied lots of interesting creatures

11. Especially finches

12. Darwin’s Finches Finches on different islands developed
type beaks due to
natural selection
according to type
of food available.

13. Finches Ground finch – Seed eater Small tree finch – Insect eater
Woodpecker finch – Tool user

14. Beak Variation
Throughout many generations the beak shape changes depending on the available food sources.
The changes are reflected in the genetic differences of the finches.
The finches adapt to the food source that is available

15. Natural selection requires three conditions to be met
Variation must exist in the population
These variations lead to differences in reproductive success of individuals
These variations are transmitted to the next generation

16. The Peppered Moth Studied for the last two hundred years.
Majority had light colors, camouflage while on trees and lichen.
Pollution in England caused lichens to die during the Industrial Revolution.
Trees became black with soot causing moths to die off due to predators.
This helped the darker moths flourish because they were ability to hide on dark trees.

17. Peppered moth
Moths adapt to pollution on tree bark better camouflaged survive
Problem: peppered moths do not rest on tree trunks!

18. Examples of natural selection
Evolution of drug resistance in HIV

19. Antibiotic Resistant bacteria

21. Artificial selection The breeding of domestic plants and animals
Traits are SELECTED by scientists, or breeders

22. Corn artificially selected

23. Evidence for evolution
Fossil Evidence
Anatomical Evidence
Vestigial structures
Embryological Homology
Molecular Homologies

24. 1. Fossil Evidence
Fossilization is an event that preserves evidence of past living organisms
Fossilization is relatively rare in softer tissue
There are fossils found that appear to be possible ancestors of modern organisms
Some transition fossils (intermediates) have been found, but never as many as Darwin predicted

25. archaeopteryx Winged reptile.
Possible link between reptiles and birds.
Probably a type of velociraptor

26. Horse evolution
Has more fossil evidence than any other but still has several gaps.

27. 2) Anatomical Evidence Homologous structures Analogous structures
Vestigial organs

28. Homologous structures
Homologies
Structural resemblance that possibly indicate related ancestry of species
Ex. Bat wing, cat leg

29. Analogous structures Analogies-
Structures that are similar in function but different in development and don’t indicate relationship
Ex. Bird wing and insect wing

30. Analogies or homologies

31. Analogies or homologies

32. Analogies or homologies

33. 3) Vestigial structures
Structures that have little or no use in an organism. (historical remnants)
Ex. Whales and snakes with vestigial hip bones

34. 4) Embryological Homologies
Haeckel (1874) Said all vertebrate classes pass through an identical evolutionarily progression though out development

35. Proved NOT true
Actual photographs

36. However
There are some similarities between all vertebrate embryos at early development. Pharyngeal pouches (similar to gill slits) and tails

37. 5) Molecular Homologies
Similar DNA and Proteins
The Primary evidence to determine relatedness

38. Similarities in DNA Sequence38 38

39. Comparative hemoglobin structure
Why compare DNA & proteins across species?
The sequence in DNA & proteins is a molecular record of evolutionary relationships. 10 20 30 40 50 60 70 80 90
100
110
120
Lamprey
Frog
Bird
Dog
Macaque
Human 32 8 45 67
125
Comparative hemoglobin structure
Why compare these genes?
Molecular Record
What are we comparing here? - comparing DNA (base sequence) & proteins (amino acid sequence)
What assumption do we make about genes and relatedness?  the more closely related, the more DNA bases & amino acids you have in common
have to compare genes for protein the organisms have in common… can’t compare genes for proteins you don’t have
compare common genes
cytochrome C (respiration)
hemoglobin (gas exchange)
Number of amino acid differences between
hemoglobin (146 aa) of vertebrate species and that of humans

40. Patterns of Evolution Co-evolution Convergent evolution
Divergent evolution

41. Co-evolution when 2 organisms evolve together
Ex. star orchid and hawk moth
Each Have specific structures adapted to each other for pollination

42. coevolution Host – parasite Hook worm – lives in humans
Can provide humans with disease prevention and lower bad immune response

43. Convergent evolution
Organisms that appear similar but are not closely related. Developed similar structures for same environment independently
Ex. Shark and porpoise = fish and mammal

44. Divergent evolution
–When related species become more and more different.
Ex. German shepherd and poodle = both dogs

45. Elephant and mammoth Called divergent parallel evolution
Thought to have a common ancestor long ago, and then evolved similarly

46. Biogeography Geographic isolation leads to differences
                              
Biogeography
Geographic isolation leads to differences
The flying lizards (genus Draco) of Southeast Asia. Differ in size according to location