1. Changes in Organisms Over Time1

2. Age of Earth
Scientist believe that the Earth is 4.6 Billion years old.
Rock data, environmental changes
Evidence:
CLIP 2

3. Natural Selection Also know as “survival of the fittest”.
Ones that are most suited to the environment.
Only certain members of the population will survive and reproduce 3

4. What if the environment changes?
The organisms that are most suited will survive, the others will die.
This is a very slow process….does not occur over night…many generations must past before any change in the population can be seen. 4

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6. 6

7. 7

8. Example: Peppered Moth
Two versions of the moth-
Black and Peppered
During the industrial revolution on England
Population of moths changed
WHY??? 8

9. 9

10. Decent with modifications
Organisms that were once the same have now grown “apart” and have become different organisms.
Overtime natural selection produces organisms that have different structures.
These changes increase a species’ fitness in their environment. 10

11. History
James Hutton Propsed that he Earth is millions of years old.
Thomas Malthus populations outgrew food supplies, causing competition and a struggle for one species to survive against another
Jean-Baptiste Lamark -inheritance of acquired characteristics 11

12. History Continued
Lylle plant and animal species had arisen, developed variations, and then became extinct over time
Alfred Russel Wallace idea of competition for resources as the main force in natural selection
Charles Darwin Publishes “On the Origin of Species” 12

13. Charles Darwin British Naturalist 1809 -1882 13
“I have called this principle, by which each slight variation, if useful, is preserved, by the term Natural Selection.” —Charles Darwin from "The Origin of Species" 13

14. 1831 to 1836-Darwin served as naturalist aboard the H. M. S
1831 to 1836-Darwin served as naturalist aboard the H.M.S. Beagle on a British science expedition around the world.
In South America Darwin found fossils of extinct animals that were similar to modern species.
Galapagos Islands - noticed many variations among plants and animals of the same general type as those in South America.
CLIP 14

15. 15 Humans select and breed for certain traits.
Artificial selection- intentional breeding for certain traits
People have been artificially selecting domesticated plants and animals for thousands of years.
Examples: Broccoli and brussels sprouts bear little superficial resemblance to their wild mustard relatives (left).
Humans select and breed for certain traits.
Examples: The largest hog, the cow that gives the most milk, or fastest horse. 15

16. Evidence for Change Over Time
Fossil Record
Fossils that show how the same organism looked millions of years ago.
Use rock layers
Isotope dating 16

17. Relative Dating 17

18. 18

19. Homologous structures
Structures that have different mature forms in different organisms but have developed from the same type of tissue. 19

20. Embryology
Early development of an organism 20

21. Stages of development from an embryo21

22. Vestigial organs
Organs or structures that do not seem to be used by the organism any longer.
They are usually reduced in size. 22

23. Evidence in Genetics to Show Change Over Time
DNA sequences in organisms are close
Sources of genetic variation in species:
Mutations
Gene Shuffling
Crossing over
during meiosis 23

24. Speciation is the evolution of a new species 24
occurs when interbreeding happens, or when the production of fertile offspring is prevented
natural barriers form and cause the breakup of populations to form smaller populations
Examples: Volcanoes, sea-level changes, and earthquakes 24

25. Speciation Mechanisms25
Behavioral Isolation
Populations are capable of interbreeding, but have different courtship rituals or other type of behavior.
Geographic Isolation
Separated by bodies of water or mountains.
Temporal Isolation
Reproduction takes place at different times of the year
Overtime they can change so much that they become unable to breed as they adapt to their environment.

26. 26 Gene Pool Combined genetic information of a particular population.
All the genes present with in a population
Can change 26

27. Changes in allele frequency within a population
Genetic drift
Random changes in allele frequency that occurs in small populations
Also know as the “founder effect”
Populations may move into a new area and the alleles that carry with them will be passed on to their offspring. 27

28. 3 Types of Evolution
1) Divergent
2) Convergent
3) Co-Evolution

29. Divergent Evolution
Divergent evolution is the process of two or more related species becoming more and more dissimilar.
Ex:The red fox and the kit fox provide and example of two species that have undergone divergent evolution.
Red Fox 29
Kit Fox

30. Convergent Evolution
the emergence of biological structures or species that exhibit similar function and appearance but that evolved through widely different evolutionary pathways.
examples include the multiple origins of wings (bats, birds) and eyes. 30

31. 31 Coevolution Examples: Predators and their prey
Parasites and their hosts
Plant-eating animals and the plants upon which they feed
plants and the animals that pollinate them.
Coevolution is the joint change of two or more species in close interaction. 31

32. Evolution is the change in a species over time.32

33. Phylogenetic Trees 33 Shows how closely organisms are related
Are whales more closely related to camels or humans?
Are snakes more closely related to birds or camels? 33

34. Phylogenetic Trees (cont.)
Which are more closely related, sharks and amphibians or sharks and ray-finned fish?
Which 2 species are the most closely related because they have hair? How did you know 34

35. Rates of Evolution
Gradualism
Punctuated Equilibrium 35

36. Gradualism & Punctuated Equilibrium
A species can evolve by only one of these, or by both.
CLIP
Species with a shorter evolution evolved mostly by punctuated equilibrium
Species with a longer evolution evolved mostly by gradualism. 36

37. Punctuated equilibrium
Gradualism
Very gradually, over a long time....
Small variations that fit an organism slightly better to its environment are selected for
Change is slow, constant, and consistent.
Punctuated equilibrium
change comes in spurts.
period of very little change, and then one or a few huge changes occur
often through mutations in the genes of a few individuals. 37

38. Resistance in Bacteria due to Evolution38
Read page p403.

39. 39

40. Two main sources of genetic variation
Mutations
Genetic Shuffling 40

41. EOCT- It is important that you are able to explain how the concepts of genetics provide the basis for explaining natural selection and evolution. This will help you answer questions like this:
What is the end result of natural selection?
A increased number of offspring of a given phenotype that survive
B changes in the frequency of alleles in a population
C fossil formation through extinction
D environmental changes of a habitat 41

42. Although the Arctic fox and the kit fox are closely related, they look very different because the individuals
A acquired traits during their lifetimes that contributed to survival
B with traits most suited to their environments reproduced most successfully
C migrated long distances to environments that most suited their traits
D passed on to their offspring acquired behaviors that were helpful 42

43. 43 Fossils of Archeopteryx show that this
animal had feathers, like a bird. It also
had a bony tail, teeth, and claws on
its wings, like a reptile. This fossil
is evidence that supports the idea that
A birds and reptiles have a common ancestor
B birds have changed very little over 150 million years
C reptile species are more advanced than bird species
D reptiles are warm-blooded like birds 43

44. Horses and tapirs have a common ancestor, but now look very different
Horses and tapirs have a common ancestor, but now look very different. Horses now are grassland animals adapted for grazing on grass and shrubs. Tapirs are jungle animals that live in dense forests and eat fruit, leaves and aquatic vegetation. Which of the following led to the development of such differences in the two species?
A selective breeding
B convergent evolution
C DNA hybridization
D natural selection 44