1. Fossils have been found of organisms that no longer live on Earth.
Ch.14 – History of Life
14.1 – Fossil Evidence of Change
Fossils have been found of organisms that no longer live on Earth.
Traces (fossils) of modern organisms can only be dated back to a certain point in the Earth’s 4.6 billion year history.
Therefore, Life on Earth has changed (EVOLVED) over the course of the Earth’s history and continue to do so.
What do we know about fossils and their age?
How/Why do living things change over time?

2. Any evidence of an organism
Ch.14 – History of Life
14.1 – Fossil Evidence of Change
Fossils
Any evidence of an organism
Replacement
Mold & Cast
Trace
Petrified
Preserved

3. Nearly all fossils form in sedimentary rock
Ch.14 – History of Life
14.1 – Fossil Evidence of Change
Nearly all fossils form in sedimentary rock
because it prevents rapid decomposition
(99% of all living things left no fossils behind)

4. Fossil Dating Relative Dating Absolute Dating Radiometric Dating
Ch.14 – History of Life
14.1 – Fossil Evidence of Change
Fossil Dating
Relative Dating
Absolute Dating
Based on the law of superposition:
newer layers of rock form on top of older layers
Radiometric Dating
Uses the half life of radioactive isotopes in order to determine specific age.
-Cannot give exact age
-Earth’s geology is constantly shifting changing the position of artifacts

5. Fossil Dating Relative Dating Absolute Dating Radiometric Dating
Ch.14 – History of Life
14.1 – Fossil Evidence of Change
Fossil Dating
Relative Dating
Absolute Dating
Based on the law of superposition:
newer layers of rock form on top of older layers
Radiometric Dating
Uses the half life of radioactive isotopes in order to determine specific age.
-Cannot give exact age
-Earth’s geology is constantly shifting changing the position of artifacts

6. Half-life – 4.5 billion years
Ch.14 – History of Life
14.1 – Fossil Evidence of Change
Absolute Dating
U238 decays to Pb206
Half-life – 4.5 billion years
C14 decays to N14
Half-life – 5730 years
Age=(halflife/.693)(Ln(1 / %remaining))

7. Geologic Time Scale Precambrian
Ch.14 – History of Life
14.1 – Fossil Evidence of Change
Geologic Time Scale
Precambrian
4600mya – 542mya
Earth formed about 4.6 billion years ago
It took about 500 million years for the crust to form and for water to start collecting on the surface
Prokaryotic & eukaryotic unicellular organisms emerge
Autotrophic prokaryotes begin to enrich the atmosphere with O2.
Multicellular organisms emerge (1st animals)

8. Life moves out of the oceans Insects, amphibians, reptiles scatter
Ch.14 – History of Life
14.1 – Fossil Evidence of Change
Paleozoic
488mya – 251mya
Animals diversify
1st plants
1st vertebrates
Life moves out of the oceans
Insects, amphibians, reptiles scatter
Ferns & Evergreens cover the Earth

9. Gymnosperms (seed-bearing plants) diversify Flowering plants appear
Ch.14 – History of Life
14.1 – Fossil Evidence of Change
Mesozoic
199mya – 65mya
1st mammals
Dinosaurs
Birds
Gymnosperms (seed-bearing plants) diversify
Flowering plants appear
Mass extinction wiped out all dinosaurs, except for the birds, at the end of the era.

10. Mammals diversify and scatter Flowering plants scatter Primates appear
Ch.14 – History of Life
14.1 – Fossil Evidence of Change
Cenozoic
55mya – present
Mammals diversify and scatter
Flowering plants scatter
Primates appear
Humans create civilizations
and pollution

11. Spontaneous Generation
Ch.14 – History of Life
14.2 – Origin of Life
Origin of Life
Early Ideas
Spontaneous Generation
Life arises from non-life
Francisco Reddi 1668
Louis Pasteur mid 1800’s
Biogenesis Life arises from existing life

12. Origin of Life Ch.14 – History of Life 14.2 – Origin of Life
Origin Movie

13. Darwin made two main points in his book:
Ch.15 – Evolution
15.1 – Darwin’s Theory of Natural Selection
A new era of biology began on November 24, 1859, the day Charles Darwin published On the Origin of Species by Means of Natural Selection
Darwin made two main points in his book:
1. Many current species are descendants of ancestral species
2. Natural selection is the mechanism for this evolutionary process

14. Ch.15 – Evolution
15.1 – Darwin’s Theory of Natural Selection
Darwin’s Influences:
Geologists Hutton and Lyell (late 1700’s) perceived that changes in Earth’s surface can result from slow continuous actions still operating today (gradualism)
Thomas Robert Malthus (late 1700’s) hypothesized that in nature plants and animals produce far more offspring than can survive, and that Man too is capable of overproducing if left unchecked

15. Darwin’s Observations:
Ch.15 – Evolution
15.1 – Darwin’s Theory of Natural Selection
Darwin’s Observations:
He observed plant and animal adaptations from many diverse environments
After graduating college Darwin was accepted on board the HMS Beagle, which circled the world from

16. Many of the islands had unique climate & vegetation
Ch.15 – Evolution
15.1 – Darwin’s Theory of Natural Selection
Darwin’s most famous observations were of finches found on the Galapagos Islands off the coast of Ecuador
Many of the islands had unique climate & vegetation
Similar looking finches found on the different islands had different adaptations from each other and were different from finches found on the mainland

17. Ch.15 – Evolution
15.1 – Darwin’s Theory of Natural Selection
Upon return to England Darwin began reflecting on his observations and started hypothesizing about how populations change over time.
He did not agree with French scientist Jean-Baptiste Lamarck that living things changed due to use and disuse of certain characteristics

18. Reproductive Advantage
Ch.15 – Evolution
15.1 – Darwin’s Theory of Natural Selection
With his knowledge of artificial selection – done by farmers for centuries in order to improve their livestock or crop populations, and the observations made on the HMS Beagle, Darwin put together his theory of
Natural Selection
Heritable
Genetic
Variation
Over-
production
Reproductive Advantage + =
Original Population
New Population
Descent with Modification

19. Survival of the Fittest
Ch.15 – Evolution
15.1 – Darwin’s Theory of Natural Selection
Survival of the Fittest
An adaptation is any characteristic that increases fitness, which is defined as the ability to survive and to produce fertile offspring
Living things adapt to their environment
Genetic
Variation
Over-
production
Reproductive Advantage + =
Original Population
New Population
Descent with Modification

20. Evidence for Evolution Comparative Embryology Comparative Biochemistry
Ch.15 – Evolution
Evidence for Evolution
Evidence for Evolution
The Darwinian view of life predicts that evolutionary transitions should leave signs in the fossil record
Paleontologists have discovered fossils of many such transitional forms
The Fossil Record
Comparative Anatomy
Comparative Embryology
Comparative Biochemistry

21. Ch.15 – Evolution
Evidence for Evolution
The Fossil Record
The Darwinian view of life predicts that evolutionary transitions should leave signs in the fossil record
Paleontologists have discovered fossils of many such transitional forms

22. Comparative Anatomy Analogous Structures
Ch.15 – Evolution
Evidence for Evolution
Most animals show similarities in internal structure
Comparative Anatomy
Homologous
Structures
Vestigial
Structures
Similar structure – different use
Structures with reduced function (“leftover parts”)
Just because structures perform a similar function does not mean they are evidence of common ancestry
Analogous Structures
Similar use – different structure

23. Comparative Embryology
Ch.15 – Evolution
Evidence for Evolution
Comparative Embryology
Vertebrate embryos exhibit homologous structures during certain phases of development

24. Insert info about biological resistance…visualizing evolution…
Ch.15 – Evolution
Evidence for Evolution
Insert info about biological resistance…visualizing evolution…

25. Comparative Biochemistry
Ch.15 – Evolution
Evidence for Evolution
Comparative Biochemistry
Many organisms share complex biomolecules. The more closely related the more similar the molecules

26. Have you been paying attention?
1. How does the concept of “descent with modification” explain both the unity and diversity of life?
4. Increased UV irradiation causes the skin of humans to become more darkly pigmented over a period of days. The notion that the offspring of such tanned individuals should consequently inherit darkened skin from their parents is consistent with the ideas of whom?
2. Explain how over-reproduction and heritable variation relate to evolution by natural selection
3. If you found a fossil of a mammal that lived high in the Andes, would you predict that it would more closely resemble present –day mammals from South American jungles or present –day mammals that live high in Asian mountains? Explain.
5. Most species of whale have 5 phalange (finger bones) supporting their flippers. Why would a whale have fingers? What would you call those phalange?

27. Population Genetics Macroevolution
Ch.15 – Evolution
15.3 – Shaping Evolutionary Theory
Population Genetics
Macroevolution
The Gene Pool is all of the alleles found in a population
Natural selection works on individuals but only populations evolve
Evolution is the change of the allelic frequency in a population BB bb Bb
20 bugs
40 alleles for color
(incompletely dominant) bb BB Bb
B – 18/40 = .45
b - 22/40 = .55
Over Time
B – 12/40 = .30
b - 28/40 = .70

28. Populations evolve due to three main causes:
Ch.15 – Evolution
15.3 – Shaping Evolutionary Theory
Populations evolve due to three main causes:
Natural Selection – Genetic Drift – Gene Flow
Natural Selection alters populations in one of three ways
Original Population Distribution
Stabilizing Selection
Disruptive Selection
Directional Selection
The average is selected for
Both extremes are selected for
One Extreme is selected for

29. Usually only occurs in small populations
Ch.15 – Evolution
15.3 – Shaping Evolutionary Theory
Populations evolve due to three main causes:
Natural Selection – Genetic Drift – Gene Flow
Genetic Drift is random changes in a gene pool usually due to independent assortment
Usually only occurs in small populations
2 Examples
Founder Effect
Bottleneck Effect
A population declines to a small # and then rebounds
A small sample of the population relocates X X X X X X X X X X X X X X X X X X

30. Populations evolve due to three main causes:
Ch.15 – Evolution
15.3 – Shaping Evolutionary Theory
Populations evolve due to three main causes:
Natural Selection – Genetic Drift – Gene Flow
Gene Flow is the exchange of genes between populations from migration

31. Populations can also evolve due to nonrandom mating and mutations
Ch.15 – Evolution
15.3 – Shaping Evolutionary Theory
Populations can also evolve due to nonrandom mating and mutations
Therefore, according to the Hardy-Weinberg Principle
A population in genetic equilibrium must meet 5 conditions:
No Genetic Drift
No Gene Flow
No Mutation
Random Mating
No Natural Selection

32. Reproductive isolation either occurs
Ch.15 – Evolution
15.3 – Shaping Evolutionary Theory
Speciation
New species arise because of reproductive isolation
Reproductive isolation either occurs
with a physical barrier or without a physical barrier
Allopatric
Sympatric
Speciation Animation

33. There are two hypothesis as to how different species come to exist
Ch.15 – Evolution
15.3 – Shaping Evolutionary Theory
There are two hypothesis as to how different species come to exist
Punctuated Equilibrium
Gradualism
Changes occur rapidly between periods of little change
Changes occur little by little

34. Organisms not closely related evolve similar traits
Ch.15 – Evolution
15.3 – Shaping Evolutionary Theory
Patterns of Evolution
Divergent Evolution
Convergent Evolution
or Adaptive Radiation
Organisms not closely related evolve similar traits
Many species arise from one original species

35. Patterns of Evolution Coevolution
Ch.15 – Evolution
15.3 – Shaping Evolutionary Theory
Patterns of Evolution
Convergent Evolution
Divergent Evolution
or Adaptive Radiation
Many species arise from one original species
Organisms not closely related evolve similar traits
Coevolution
Many species evolve in close relationship with other species