1. EVOLUTION

2. Charles Darwin

3. Question for Thought
Earth has millions of other kinds of organisms of every imaginable shape, size, and habitat.
This variety of living things is called biodiversity.
How did all these different organisms arise?
How are they related?

4. In your own words, describe what YOU think the theory of evolution means…

5. Darwin’s Theory of Evolution
Evolution, or change over time, is the process by which modern organisms have descended from ancient organisms.
A scientific theory is a well-supported testable explanation of phenomena that have occurred in the natural world.

6. How do you think Darwin came up with his theory?

7. Voyage of Beagle Dates: February 12th, 1831 Captain: Charles Darwin
Ship: H.M.S. Beagle
Destination: Voyage around the world.
Findings: evidence to propose a revolutionary hypothesis about how life changes over time

9. The Galapagos Islands
The smallest, lowest islands were hot, dry, and nearly barren-Hood Island-sparse vegetation
The higher islands had greater rainfall and a different assortment of plants and animals-Isabela- Island had rich vegetation.

10. The Galapagos Islands
Darwin was fascinated in particular by the land tortoises and marine iguanas in the Galápagos.
Giant tortoises varied in predictable ways from one island to another.
The shape of a tortoise's shell could be used to identify which island a particular tortoise inhabited.

12. Animals found in the Galapagos
Land Tortoises
Darwin Finches
Blue-Footed Booby
Marine Iguanas

13. Animals

14. The Journey Home
Darwin Observed that characteristics of many plants and animals vary greatly among the islands
Hypothesis: Separate species may have arose from an original ancestor

15. Lamarck

18. Population Growth Thomas Malthus-19th century English economist
If population grew (more babies born than die)
Insufficient living space
Food runs out
Darwin applied this theory to animals

19. Natural Selection & Artificial Selection
Natural selection-differences among individuals of a species caused by nature
Artificial selection- nature provides the variation among different organisms, and humans select those variations they find useful.

20. Evolution by Natural Selection
The Struggle for Existence-members of each species have to compete for food, shelter, other life necessities
Survival of the Fittest-Some individuals better suited for the environment

21. Natural Selection
Over time, natural selection results in changes in inherited characteristics of a population. These changes increase a species fitness in its environment

22. Evidence of Evolution The Fossil Record
Geographic Distribution of Living Things
Homologous Body Structures
Similarities in Early Development

23. We found the fossil — no joke!
Land Mammal ?
Complete series of transitional fossils ?
Where are the intermediate fossils? ? ?
There are innumerable intermediate & transitional forms
Whales as land creatures returning to the water….
Where are the intermediate forms of whale ancestors?
Cartoon making fun of this idea.
The cartoons disappeared years ago when this fossil was found.
Ambilocetic natans = “Walking whale who likes to swim”
4-5 intermediate forms all found in last 2 decades
Indus River valley in between India & Pakistan.
Someone’s idea of a joke!
Ocean Mammal
But the joke’s on them!!

24. Evolution from sea to land
2006 fossil discovery of early tetrapod
4 limbs
Missing link from sea to land animals

25. 3. Anatomical record Animals with different structures on the surface
But when you look under the skin…
It tells an evolutionary story of common ancestors

26. How could these very different animals have the same bones?
Compare the bones
The same bones under the skin
limbs that perform different functions are built from the same bones
How could these very different animals have the same bones?

28. Homologous structures
Structures that come from the same origin
homo- = same
-logous = information
Forelimbs of human, cats, whales, & bats
same structure
on the inside
same development in embryo
different functions
on the outside
evidence of common ancestor

29. But don’t be fooled by these…
Analogous structures
look similar
on the outside
same function
different structure & development
on the inside
different origin
no evolutionary relationship
How is a bird like a bug?
Solving a similar problem with a similar solution

30. Analogous structures Dolphins: aquatic mammal Fish: aquatic vertebrate
both adapted to life in the sea
not closely related
Watch the tail!

31. Because they used to walk on land!
Vestigial structures
Hind leg bones on whale fossils
Why would whales have pelvis & leg bones if they were always sea creatures?
Because they used to walk on land!

32. Vestigial structures
Structures on modern animals that have no function
remains of structures that were functional in ancestors
evidence of change over time
some snakes & whales have pelvis bones & leg bones of walking ancestors
eyes on blind cave fish
human tail bone

35. Comparative embryology
Development of embryo tells an evolutionary story
similar structures during development
all vertebrate embryos have a “gill pouch” at one stage of development

36. Comparative Embryology

37. Figure 11.14
Comparative embryology. All vertebrates go through an embryonic stage in which they have four limb buds and a tail. From top to bottom: human, mouse, bat, chicken, and alligator embryos.
Human

38. Mouse
Figure 11.14
Comparative embryology. All vertebrates go through an embryonic stage in which they have four limb buds and a tail. From top to bottom: human, mouse, bat, chicken, and alligator embryos.

39. Bat
Figure 11.14
Comparative embryology. All vertebrates go through an embryonic stage in which they have four limb buds and a tail. From top to bottom: human, mouse, bat, chicken, and alligator embryos.

40. Figure 11.14
Comparative embryology. All vertebrates go through an embryonic stage in which they have four limb buds and a tail. From top to bottom: human, mouse, bat, chicken, and alligator embryos.
Chicken

41. Figure 11.14
Comparative embryology. All vertebrates go through an embryonic stage in which they have four limb buds and a tail. From top to bottom: human, mouse, bat, chicken, and alligator embryos.
Alligator

42. 3. Molecular record Comparing DNA & protein structure
everyone uses the same genetic code!
DNA 10 20 30 40 50 60 70 80 90
100
110
120
Lamprey
Frog
Bird
Dog
Macaque
Human 32 8 45 67
125
compare common genes
compare common proteins
number of amino acids different from human hemoglobin

43. Building “family” trees
Closely related species are branches on the tree — coming from a common ancestor

44. “descendants” of wild mustard
Artificial selection
How do we know natural selection can change a population?
we can recreate a similar process
“evolution by human selection”
“descendants” of wild mustard

45. “descendants” of the wolf
Selective Breeding
Humans create the change over time
“descendants” of the wolf

46. I liked breeding pigeons!
Artificial Selection
…and the examples keep coming!
I liked breeding pigeons!

47. Artificial Selection gone bad!
Unexpected consequences of artificial selection
Pesticide resistance
Antibiotic resistance

48. Insecticide resistance
Spray the field, but…
insecticide didn’t kill all individuals
What caused the variation?
mutation
resistant survivors reproduce
resistance is inherited
insecticide becomes less & less effective
The evolution of resistance to insecticides in hundreds of insect species is a classic example of natural selection in action.
The results of application of new insecticide are typically encouraging, killing 99% of the insects.
However, the effectiveness of the insecticide becomes less effective in subsequent applications. The few survivors from the early applications of the insecticide are those insects with genes that enable them to resist the chemical attack. Only these resistant individuals reproduce, passing on their resistance to their offspring. In each generation the % of insecticide-resistant individuals increases.

50. Any Questions??