1. Changes in Organisms Over Time1

2. Unit Learning Goals 2 a. Trace the history of the theory.
b. Explain the history of life in terms of biodiversity, ancestry, and the rates of evolution.
d. Relate natural selection to changes in organisms.
c. Explain how fossil & biochemical evidence support the theory.
e. Recognize the role of evolution to biological resistance (pesticide & antibiotic resistance).

3. 3
Age of Earth
Scientist believe that the Earth is 4.6 billion years old.
Evidence:
-Rock data,
-Environmental changes
CLIP

4. Where do I live? 4 What type of environment am I best “fit” for?
Hot/cold????
Wet/dry???
Why
Organisms have traits (GENES) that help them to survive in different environments.

5. What is Fitness? 5
Fitness is a measure of reproductive success. (survive long enough to reproduce)
Reproductive success: Having traits so that an organism is able to pass on genes onto the next generation (and in a way so that the next generation can also pass those genes on)
Any trait that promotes survival — at least until one's reproductive years are over — increases fitness.
Such traits are called adaptations.
GAME

6. What if an organism has a trait
What if an organism has a trait. that makes it impossible to live in its environment? 6
The organism will not survive.
If it does not survive—it CANNOT reproduce.
If it does not reproduce—its genes are not passed to the next generation.

7. What if the environment changes?7
If they do not have the traits (genes) that enable them to survive…they die, and DO NOT reproduce.
If they do have the traits, then they survive…and reproduce.
SO… the next generation has more of the “fit” traits for THAT environment.
The population then CHANGES!
This is a very slow process….does not occur over night…many generations must past before any change in the population can be seen.
Natural Selection

8. Current Theory … Natural Selection8
Also know as “survival of the fittest.”
Only certain members of the population will survive and reproduce.
Ones that survive are most suited to the environment—they are the most fit!!.
survival of the fittest

9. Humans have been doing this for 1000s of years!9
Artificial selection provides a model that helps us understand natural selection. People have been artificially selecting domesticated plants and animals for thousands of years.
Broccoli and brussels sprouts bear little superficial resemblance to their wild mustard relatives (left).

10. Humans select and breed for certain traits.
Dog Breeds
Corn
Pigs
Humans select and breed for certain traits.
Examples: The largest hog, the cow that gives the most milk, fastest horse, or cutest dog.

11. Where do NEW traits come from?10
Where do NEW traits come from?

12. How do new traits arise? Mutations. Sexual Reproduction. 11
Mixing of genes makes new combinations
A combo of traits may be necessary for survival……so… sexual reproduction and crossing over can create new combination of traits.

13. Decent with modifications12
Overtime natural selection produces organisms that have different structures, established different niches, or occupy different habitats.
Organisms that were once the same have now grown “apart” and have become different organisms.
These changes increase a species’ fitness in their environment.

14. These traits will be passed on to the next generation. 13
THE BASICS: A review
ADAPTATIONS (traits) that are favorable become more prevalent within that population.
These traits will be passed on to the next generation.
The GENE POOL of a population CHANGES in favor of the “FITTEST” phenotype & genotype!!!

15. Environment selecting “good” traits for THAT environment.
Natural
Selection
Examples 14

16. Example: Peppered Moth15
Two versions of the moth-
Black and peppered
During the industrial revolution on England
Population of moths changed

17. 16

18. the larger birds were favored over the smaller ones
From 1976 through 1977, a severe drought struck an island in the Galapagos. 17
Sampling the birds that died as well as those that survived showed that
the larger birds were favored over the smaller ones
those with larger beaks were favored over those with smaller ones.
of Small beaks
Beak length (mm)
Beak depth (mm)
Dead birds
10.68
9.42
Survivors
11.07
9.96
Some phenotypes are more fit than others when it comes to competing for resources. The more “FIT” phenotype will survive and have the possibility of passing its alleles to the next generation.

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History

22. History 21
James Hutton Proposed that the Earth is millions of years old.
Many land formations took millions of years to form.
Known as the founder of modern geology.

23. History Thomas Malthus -1798-22
Thomas Malthus
Proposed that populations outgrew their food supplies, causing competition between organisms and a struggle for one species to survive against another
This "struggle for existence" drives population change.

24. History Jean-Baptiste Lamark -1809-23
Jean-Baptiste Lamark
Believed that all life forms evolved and that the driving force of evolution was the inheritance of acquired characteristics.
He believed that organisms changed due to the demands of their environment.

25. What we understand now:24
What we understand now:

26. the present is the key to understanding the past25
Charles Lyell proposed that plant and animal species had arisen, developed variations, and then became extinct over time.
He believed that every animal or plant, including humankind, was adapted to the niche in which it was created.
the present is the key to understanding the past
He also believed that the Earth’s physical landscape changed over a long period of time.
15.1

27. Alfred Russel Wallace -185826
Alfred Russel Wallace -1858
Emphasis was based on the idea of competition for resources as the main force in natural selection.
Best known for independently proposing a theory of natural selection which prompted Charles Darwin to publish on his own theory
15.2

28. Charles Darwin -1859- Publishes “On the Origin of Species”27
Charles Darwin Publishes “On the Origin of Species”
Believed that Natural Selection is the driving force for evolution.

29. Charles Darwin British Naturalist 1809 -1882 28
“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"

30. From 1831 to 1836 Darwin served as a naturalist aboard the H. M. S
From 1831 to 1836 Darwin served as a 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.
On the Galapagos Islands in the Pacific Ocean he noticed many variations among plants and animals of the same general type as those in South America. 29
CLIP

31. Summary of Darwin’s Ideas30
Individual organisms differ, and some of this variation is heritable.
Organisms produce more offspring than can survive, and many that do survive do not reproduce.
Because more organisms are produced than can survive, they compete for limited resources.
Individuals best suited to their environment survive and reproduce most successfully.

32. Summary of Darwin’s Ideas31
These organisms pass their heritable traits to their offspring. Other individuals die or leave fewer offspring.
This process of natural selection causes species to change over time.
Species alive today are descended with modification from ancestral species that lived in the distant past.
This process, by which diverse species evolved from common ancestors, unites all organisms on Earth into a single tree of life.
Review Clip

33. 32
Evidence

34. Evidence for Change Over Time33
Fossil Record
Fossils that show how the same organism looked millions of years ago.
Paleontology
Use rock layers
1) Isotope dating

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Fossil Record

36. 2) Relative Dating 35

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38. Homologous structures
Structures that have different mature forms in different organisms but have developed from the same type of tissue.
Homologous structures 37

39. Homologous structures38

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Embryology
Early development of the organism

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Stages of Development

42. Vestigial organs 41
Organs or structures that do not seem to be used by the organism any longer.
They are usually reduced in size.

43. Vestigial Organs 42 c

44. Things that cause change. Why we are all a little bit different…43
Genetics
DNA sequences in organisms are close
Sources of genetic variation in species:
Mutations
Gene Shuffling
Crossing over during meiosis
Sexual Reproduction
Things that cause change.
Why we are all a little bit different…

45. Genetic Comparison 44

46. The numbers represent the number of amino acid differences between the beta chain of humans and the hemoglobins of the other species.
In general, the number is inversely proportional to the closeness of kinship.

47. GEOGRAPHIC DISTRIBUTION45
Organisms that are related change/adapt according to their environment.

48. Adaptive Radiation 46
The evolution of many diversely adapted species from a common ancestor
Relatively rapid
Usually occurs when a population colonizes an area of diverse geographic or ecological conditions.
New niches
Each species becomes specialized for a different set of conditions

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Speciation
Macroevolution

53. Evolution: change in the allelic frequencies in a population51
Macroevolution
Speciation
How do we get new species?
Where do new species come from?
Species: population whose members can interbreed in nature and produce viable, fertile offspring
Evolution: change in the allelic frequencies in a population

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Speciation
In the physical world, natural barriers form and cause the breakup of populations to form smaller populations.
Volcanoes, sea-level changes, and earthquakes are a few examples of natural occurrences that affect populations

55. Speciation Mechanisms53
Speciation Mechanisms
Geographic Isolation
Separated by bodies of water or mountains.
Temporal Isolation
Reproduction takes place at different times of the year
Different Mating seasons
Overtime they can change so much that they become unable to breed as they adapt to their environment.

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Behavioral Isolation
Populations are capable of interbreeding, but have different courtship rituals or other type of behavior.
Do not recognizes another species as a mating partner.

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VOCAB CHECK

58. Combined genetic information of a particular population. 56
Gene Pool
Combined genetic information of a particular population.
All the genes present with in a population
Can change
A population is a localized group of individuals that belong to the same species.

59. Changes in allele frequency with in a population
Genetic drift— along with natural selection, mutation, and migration—is one of the basic mechanisms of evolution. 57
Changes in allele frequency with in a population
Genetic drift
Random changes in allele frequency that occurs in small populations
“Lucky” individuals leave more offspring.
Also known as the “Founder Effect”

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Patterns of
Evolution

61. Divergent Evolution 59
Divergent evolution is the process of two or more related species becoming more and more dissimilar.
The red fox and the kit fox provide and example of two species that have undergone divergent evolution.
As they adapted to different environments, the appearance of the two species diverged.

62. Two or more related species becoming more and more dissimilar
Divergent Evolution 60
Two or more related species becoming more and more dissimilar

63. Convergent Evolution
Independent development of similar structures 61
Convergent evolution is 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.

64. Convergent Evolution
Independent development of similar structures 62

65. Coevolution Predators and their prey Parasites and their hosts63
Predators and their prey
Parasites and their hosts
Plant-eating animals and the plants upon which they feed
One example of coevolution is between plants and the animals that pollinate them.
Coevolution is the joint change of two or more species in close interaction.

66. Coevolution 64
Bumblebees & the flowers they pollinate have coevolved so that both have become dependent on each other for survival.
Some Central American Acacia species have hollow thorns and pores at the bases of their leaves that secrete nectar. These hollow thorns are the exclusive nest-site of some species of ant that drink the nectar. But the ants are not just taking advantage of the plant—they also defend their acacia plant against herbivores.

67. Evolution at the species level is called microevolution.
It results from genetic variation and natural selection within a population of organisms.
Small Changes
Macroevolution is evolution that occurs between different species. 65

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69. Evolution is the change in a species over time.67
Evolution is the change in a species over time.

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Rates of Evolution

74. Gradualism & Punctuated Equilibrium72
Two ways in which the evolution of a species can occur.
A species can evolve by only one of these, or by both.
CLIP
Species with a shorter evolution evolved mostly by punctuated equilibrium, and those with a longer evolution evolved mostly by gradualism.

75. Punctuated equilibrium73
Gradualism
Very gradually, over a long time... Over a short period of time it is hard to notice.
Slow Changes
Small variations that fit an organism slightly better to its environment are selected for: a few more individuals with more of the helpful trait survive, and a few more with less of the helpful trait die.
Change is slow, constant, and consistent.
Punctuated equilibrium
change comes in spurts. There is a period of very little change, and then one or a few huge changes occur, often through mutations in the genes of a few individuals.

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77. STOP HERE>>>>>>>>>>>>>

78. Biological Resistance75
Biological Resistance
When organisms are no longer affected by a drug.
First documented around 1952
Causes: Natural consequence of selective pressures in the environment.

79. Resistance in Bacteria76
Read page p403.

80. Bacteria- Antibiotic resistance 77
Bacteria- Antibiotic resistance
Many insects have developed a resistance to insecticides. (simple point mutations)

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82. The Effects of Selection on Populations79
The Effects of Selection on Populations

83. Types of Selective Processes in Natural Selection80
Types of Selective Processes in Natural Selection
Stabilizing Selection
Directional Selection
Diversifying Selection
Balancing Selection
Heterozygote Advantage
Frequency-dependent

84. Stabilizing Selection81
Intermediate forms of a trait are favored and alleles that specify extreme forms are eliminated from a pop.
Ex: Human birth weight stay between 6-8 lbs. Lower or higher has higher mortality.

85. Directional Selection82
Changing environmental conditions give rise to directional selection, where one phenotype replaces another in the gene pool.
Can produce rapid shift in allelic frequencies.
Ex: Peppered moth
– peppered moths, pesticide resistance,
antibiotic resistance
Occur in response to:
* directional change in the environment
* one or more new environmental conditions
* a mutation that appears and proves to be adaptive

86. Diversifying (Disruptive) Selection83
Diversifying (Disruptive) Selection
Increases the extreme types in a population at the expense of the intermediate forms.
One population divided into two.
(bill size in seedcrackers)

87. Diversifying selection can result in balanced polymorphism.
For example, two distinct bill types are present in black-bellied seedcrackers in which larger-billed birds are more efficient when feeding on hard seeds and smaller-billed birds are more efficient when feeding on soft seeds. 84

88. Heterozygote Advantage
Exists when a heterozygote (Aa) has a higher fitness than either homozygote (AA, aa).
ex: Sickle Cell 85

89. Frequency dependent 86
The term given to an evolutionary process where the fitness of a phenotype is dependent on its frequency
Can arise in systems of mimicry
ex: Butterflies
ex: Maintenance of a 50:50 sex ratio: If one sex becomes more common, some of its members will not be able to mate

90. Adaptation is a key concept in natural selection. 87
Adaptation is a key concept in natural selection.
Natural selection can change the inherited characteristics in a population and possibly even result in a new species.

91. Two main sources of genetic variation88
Two main sources of genetic variation
Mutations
Genetic Shuffling (by sexual reproduction)

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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

93. A acquired traits during their lifetimes that contributed to survival 90
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

94. A. birds and reptiles have a common ancestor
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 91

95. B convergent evolution C DNA hybridization D natural selection
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 92

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97. Adaptation is the key concept in natural selection. Review CLIP94