1. What does the word “theory” mean in everyday language?
2.  What does the word “theory” mean in science?
3.  What is evolution?

2. Evolution Evolution is JUST a theory?
Theories are the single highest level of scientific achievement and nothing is just a theory.

3. Evolution Evolution: A Change Over Time Essential Questions:
 How can there be so many similarities among organisms yet so many different kinds of plants, animals, and microorganisms?
How does biodiversity affect humans?

4. Evolution Theory in Science
In science, theories are statements or models that have been tested and confirmed many times.
Theories have some important properties:
­  They explain a wide variety of data and observations.
­  They can be used to make predictions.
 They are not absolute.
­  They serve as a model of understanding the world and can be changed as the world view changes.

5. Evolution Some questions that can be answered by evolution.
Why do so many different animals have the same structures?
The arm bones in a human are the same bones as a flipper in a whale.

6. Evolution Some questions that can be answered by evolution.
Why do organisms have structures they no longer use, like the appendix or tailbone in a human ?

7. Evolution Some questions that can be answered by evolution.
Why are there bones and fossil
evidence of creatures that no
longer exist? What happened to
these
creatures?

8. Evolution Some questions that can be answered by evolution.
Why is the sequence of DNA very similar in some groups of organisms but not in others.

9. Evolution Some questions that can be answered by evolution.
Why do the embryos of animals look very similar at an early stage?

10. Evolution
The Theory of Evolution is considered a Unifying Theory of Biology, because it answers many of these questions and offers an explanation for the data.

11. Evolution
Evolution begins with variation.
NO VARIATION = NO EVOLUTION

12. Evolution What is variation? What causes variation? • Mutation
• Sex • Migration

13. Evolution þ1. Mutations may: A. Have positive effects
B.  Have negative effects
C.  Have no effect
D.  All of the above

14. Evolution 2. Whether a mutation is positive or
negative depends on the location of the mutation in the genome:
A. True
B. False

15. Evolution
þ3. Whether a mutation is positive or negative depends on the environment that the organism lives in.
A. True
B. False

16. Evolution Which of the following statements is false:
A.  Mutations occur all the time.
B.  Everyone has mutations.
C.  Mutations always lead to a decrease in success of the organism.
D.  Mutations can be caused by a variety of factors.

17. Evolution
Meiosis and fertilization allow for great diversity in sexual species compared to asexual species.
In evolutionary terms, sex is more important than life itself. Sex fuels evolutionary change by adding variation to the gene pool. The powerful urge to pass our genes on to the next generation has likely changed the face of human culture in ways we're only beginning to understand.

18. Evolution
Traits can be positive, negative or neutral in a given environment.
The alleles coding for negative traits are likely to be reduced in the presence of alleles for more favorable ones.

19. Evolution Biologically speaking, what is “success?”
Success is passing on your genes to offspring.

20. Evolution Essential requirements for Evolution
2 Variation: All life forms vary genetically within a population. It is this genetic variation upon which selection works.
2 Inheritance: Genetic traits are inherited from parents and are passed on to offspring.
2 Selection: Organisms with traits that are favorable to their survival get to live and pass on their genes to the next generation.
2 Time: Evolution takes time. Evolution can happen in a few generations, but major change, such as speciation, often takes long periods of time.

21. Evolution When you think of Evolution what person comes to mind?
CHARLES DARWIN

22. Evolution CHARLES DARWIN – 1809-1882
•  English naturalist and geologist
•  He established that all species of life have descended over time from common ancestors
•  Published his theory of evolution with compelling evidence in his 1859 book: “On the Origin of Species, overcoming scientific rejection of earlier concepts of transmutation of species.”
•  His five-year voyage on HMS Beagle established him as an eminent geologist and publication of his journal of the voyage made him famous as a popular author.

23. Evolution
Voyage of the HMS Beagle Stopped in Galapagos Islands 500 miles off coast of Ecuador.

24. Evolution What’s so important about the Galapagos Islands?
First, because they are extremely isolated, the Galapagos Islands are home for dozens of species of both plants and animals found nowhere else in the world.

25. Evolution
The Galapagos Tortoise is the largest reptile found anywhere on the planet, and it lives longer than any animal known to man.

26. Evolution
Second, Darwin’s visit to the Galapagos for five weeks in 1835 provided the starting point for the development of his theory of natural selection.

27. Evolution Darwin found many unique species
Many of Darwin’s observations made him wonder... Why?
Darwin asked:
Why were these creatures found only on the Galapagos Islands?

28. Evolution Darwin found clues in the fossils Darwin asked:
He found evidence that organisms have changed over time.
Darwin asked:
Why should extinct armadillos & modern armadillos be found on same continent?

29. Evolution Two important and unexpected patterns:
Traits exhibited by species
Galapagos finches had different beaks than finches on the mainland.

30. Evolution
2. Similarity between the fossils of extinct species and the living species in that same area.

31. Evolution The Book that Would “Rock the World”
q In 1842, Darwin finally hammered out a first draft of his ideas.
q In a letter to a close friend, he wrote “At last gleams of light have come, and I am almost convinced (quite contrary to the opinion I started with) that species are not immutable.”
The book spent 14 years in a drawer.
A letter from another scientist, Alfred Wallace, prompted Darwin to finally publish the book.

32. Ideas About Evolution Before Darwin’s book:
Organisms were all placed on Earth at the same time by a Creator.
Organisms are fixed– no
additions or subtractions.
3. Earth is about 6,000 years old.
4. Earth is mostly unchanging.

33. Ideas about Evolution After publication of Darwin’s book:
Organisms change over time.
Some organisms have gone extinct.
Earth is over 6,000 years old.
The geology of earth is not
constant – it is always
changing.

34. Earlier Ideas About Evolution
LaMarck: Earlier ideas on
Evolution
– evolution by acquired traits
creatures developed traits during their lifetime - give those traits to their offspring
– example: in reaching higher leaves, giraffes stretch their necks & give the acquired longer neck to offspring

35. This idea has been refuted!!
Evolution
LaMarck: Earlier ideas on Evolution
– Evolution by acquired traits
creatures developed traits during their lifetime - give those traits to their offspring
– example: in reaching higher leaves, giraffes stretch their necks & give the acquired longer neck to offspring
This idea has been refuted!!

36. Evolution Darwin’s view of Evolution
– giraffes that already have long necks survive better
– leave more offspring who inherit their long necks
variation
selection & survival
reproduction &
inheritance of
more fit traits

37. Evolution
They, in turn, pass their favorable traits to their offspring.
Ø The offspring are then more likely to survive.
As the process of natural selection goes on over many generations, species change.

38. Evolution is a change in allele frequencies within a population.

39. Individuals do NOT evolve.
Evolution
Individuals do NOT evolve.
Populations evolve
Allele frequencies
change

40. Evolution Agents of Evolutionary Change
1. Mutation 2. Natural selection and sexual selection
3. Migration
Evolution is genetic change in a population.

41. Agents of Evolutionary change
MUTATION Mutation is the ultimate source of genetic variation in a population.

42. Agents of Evolutionary Change
2. NATURAL SELECTION A process where organisms with traits well suited to an environment are more likely to survive and produce more offspring than organisms without these favorable traits.

43. Evolution
When three simple conditions are satisfied, evolution by natural selection occurs.
1.  There must be variation for the particular trait within a population.
2.  That variation must be inheritable.
3.  Individuals with one version of the trait must produce more offspring than those with a different version of the trait.

44. Variation

46. SEXUAL SELECTION
A special type of natural selection that acts on an organism’s ability to obtain or successfully copulate with a mate.
This process may produce traits that seem to decrease an organism’s chance of survival, while increasing its chances of mating.

47. What drives Natural Selection?
Overproduction
Competition
Variations
Survival of the fit

48. What Drives Natural Selection?
1. Overproduction
Organisms produce more offspring than the environment can support.
ØThere is not enough food or living space for all the offspring.

49. What drives Natural Selection?
Competition
Overproduction leads to a struggle.
All the organisms compete for food, water, and the other necessities of life.
Only those organisms that are well suited to their surroundings survive and reproduce.
The rest die.

50. What drives Natural Selection?
3. Variations
ØOrganisms of the same species are very similar.
ØBut they do have individual differences among traits, or variations.
These differences are important in the “struggle for survival.”

51. What drives Natural Selection?
For example, extra speed can mean the difference between life and death. A fast wildebeest may escape an attacking lion. A slower neighbor may become the lion’s next meal.

52. What Drives Natural Selection?
Survival of the Fit
Organisms with traits that make them well adapted, or suited to the environment, survive and reproduce.
Darwin used the term natural selection to describe the survival of organisms with favorable traits.

53. Fitness
Definition: how good a particular genotype is at leaving offspring in the next generation relative to how good other genotypes are at it.
Depends on the environment in which the organism lives.

54. Who has a higher fitness?

55. Discussion Questions:
1.  What does the word fitness mean?
2.  Is calling good or bad for a cricket's fitness?
3.  Give some examples of selection
at work in this cricket story.
4.  How does selection favor calling?
How does selection favor not calling?