1. Evolution
by
Natural Selection
AP Biology 2006-2007
2. mya
Quaternary
Molluscs
Anaerobic Bacteria
Chordates
Land Plants
Jawless Fish
Teleost Fish
Photosynthetic Bacteria
Green Algae
Multicellular Animals
Seed Plants
Arthropods
Amphibians
Mammals
Birds
Flowering Plants
Insects
Reptiles
1.5
Tertiary
63
Cretaceous
Dinosaurs
135
Jurassic
180
Triassic
225
Permian
280
Carboniferous
350
Devonian
400
Silurian
430
Ordovician
500
Cambrian
570
Ediacaran
700
Precambrian,
Proterozoic,
&
Archarozoic
4500
Life’s Natural History is a record of Successions & Extinctions
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3. Life has changed over time
& in turn has changed the Earth
Living creatures have
changed Earth’s environment,
making other life possible
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4. Evolution as Change Over Time
idea accepted
Evolution!
before Darwin
Evolution!
Evolution!
Evolution!
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5. LaMarck
Organisms adapted to
their environments
through acquired traits
change in their life time
Use & Disuse
organisms lost parts because they did not use them
— like the missing eyes & digestive system of the
tapeworm
Perfection with Use & Need
the constant use of an organ leads that organ to
increase in size — like the muscles of a blacksmith
or the large ears of a night-flying bat
transmit acquired characteristics to next
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6. Charles Darwin
1809-1882
British naturalist
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Collected clear
evidence to
support his ideas
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7. Voyage of the HMS Beagle
Invited to travel around the world
1831-1836 (22 years old!)
makes many observations of nature
main mission of the Beagle was to chart
South American coastline
Robert Fitzroy
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8. Voyage of the HMS Beagle
Stopped in Galapagos Islands
500 miles off coast of Ecuador
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9. Galapagos
Recent volcanic origin most
of animal species on the
Galápagos live nowhere else
in world, but they resemble
species living on South
American mainland.
AP Biology 500 miles west of mainland
10. Succession of types
Armadillos are native to the
Americas, with most species
found in South America.
Why should extinct
armadillo-like species
& living armadillos be
found on the same
continent?
Glyptodont fossils are also
unique to South America.
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11. Mylodon (left) Giant
ground sloth (extinct)
Modern sloth (right)
This wonderful relationship
in the same continent between
the dead and the living will…throw more light
on the appearance of organic beings on our earth,
and their disappearance from it,
than any other class of facts.
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13. Darwin found… birds
C
Finch? Sparrow?
Thought he found
very different kinds…
AP Biology Woodpecker? Warbler?
14. But Darwin found… a lot of finches
Darwin was amazed to
find out:
All 14 species of birds
were finches…
But there is only one
species of finch on the Large Ground
Finch?
Finch? Small Ground
Sparrow?
Sparrow?
Finch Finch
mainland!
How did
one species
of finches become
so many different
species now?
AP Biology Warbler Finch
Woodpecker?
Woodpecker? Veg. Tree Finch
Warbler?
Warbler?
15. Tree Thinking
Large-seed eater?
Large Ground Small-seed eater?
Small Ground
Finch Finch
AP Biology Warbler?
Warbler Finch Leaf-browser?
Veg. Tree Finch
16. Correlation of species to food source
Rapid speciation:
new species filling new niches,
because they inherited
successful adaptations.
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17. Darwin’s finches
Differences in beaks
associated with eating different foods
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Warbler finch Cactus finch
Woodpecker finch Sharp-beaked finch
Small insectivorous er Small ground
tree finch Warbl finch
finch
Gr
es
Large Cactus
ou
ch
insectivorous Medium
nd
fin
eater
tree finch ground finch
fin
ee
Insect eaters
Tr
ch
Seed eaters
es
Vegetarian
Bud eater Large
tree finch
AP Biology ground finch
18. Darwin’s finches
Darwin’s conclusions
small populations of original South American
finches land on islands
variation in beaks enabled individuals to gather
food successfully in the different environments
over many generations, the populations of
finches changed anatomically & behaviorally
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emergence of different species
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19. Seeing this gradation &
diversity of structure in
one small, intimately related group of birds,
one might really fancy that
from an original paucity of birds
in this archipelago,
one species has been taken &
modified for different ends.
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20. Darwin’s finches
Differences in
beaks allowed
some finches to…
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21. More observations… Correlation of species
to food source
Whoa,
Turtles, too!
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22. Many islands also show
distinct local variations in
tortoise morphology…
…perhaps these are
the first steps in the
splitting of one species
into several?
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23. This is not just
a process of
the past…
It is all
around
AP Biology us today
24. Selective
breeding
the raw genetic
material (variation)
is hidden there
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25. Selective breeding
Hidden variation
can be exposed
through selection!
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26. In historical context
Other people’s ideas paved the
path for Darwin’s thinking
competition:
struggle for survival
population growth
exceeds food supply
land masses change over
immeasurable time
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27. A Reluctant Revolutionary
Returned to England in 1836
wrote papers describing his collections
& observations
long treatise on barnacles
draft of his theory of
species formation in 1844
instructed his wife to
publish this essay upon
his death
reluctant to publish but
didn’t want ideas to die
AP Biology with him
28. And then came the letter….
Then, in 1858, Darwin received a letter
that changed everything…
Alfred Russel Wallace
a young naturalist working
in the East Indies, had
written a short paper with a
new idea. He asked Darwin
to evaluate his ideas and
pass it along for publication.
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29. The time was ripe for the idea!
To Lyell—
Your words
have come true
with a vengeance…
I never saw a more striking
coincidence…so all my originality,
whatever it may amount to,
will be smashed.
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30. Voyage: 1831-1836
November 24, 1859, Darwin published
“On the Origin of Species by Means of Natural Selection”
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32. LaMarckian vs. Darwinian view
LaMarck
in reaching higher
vegetation giraffes
stretch their necks &
transmits the acquired
longer neck to offspring
Darwin
giraffes born with longer
necks survive better &
leave more offspring who
inherit their long necks
genes
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36. Coherent explanation of observations
"Nothing in biology
makes sense except in
the light of evolution."
-- Theodosius Dobzhansky
March 1973
Geneticist, Columbia University
(1900-1975)
AP Biology 2006-2007
37. Essence of Darwin’s ideas
(1) Variation exists in natural populations
(2) Many more offspring are born each season
than can possibly survive to maturity
(3) As a result, there is a struggle for existence
- competition
(4) Characteristics beneficial in the struggle
for existence will tend to become more
common in the population, changing the
average characteristics of the population
- adaptations
(5) Over long periods of time, and given a steady input of
new variation into a population, these processes lead to
AP Biologyemergence of new species
the
39. The Birds…
Galápagos birds
22 of the 29 species of
birds on the Galapagos
are endemic
found only on these islands
collected specimens of all
One particular group…
at first, he paid little
attention to a series of
small birds
some were woodpecker-
like, some warbler-like, &
some finch-like
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40. Darwin’s finches
Darwin was amazed
to find out they were
all finches
14 species
but only one
species on SouthLarge-seed eater?
Finch? Small-seed eater?
Sparrow?
American mainland
500 miles away
all the birds had to
originally come How did
from mainland one species
of finches become
species so many different
ones now?
AP Biology Warbler?
Warbler? Leaf-browser?
Wren?
Hinweis der Redaktion
Lamarck noted how well-adapted organisms were to their environments, and believed that fossils could be understood as less perfect forms which had perished in the struggle for increasing perfection. He explained adaptation as a result of change caused by environmental pressures.
What did Darwin say? What evidence supports Evolution by Natural Selection? What impact did Evolution have on biology?
After graduation Darwin was recommended to be the conversation companion to Captain Robert FitzRoy, preparing the survey ship Beagle for a voyage around the world. FitzRoy chose Darwin because of his education, his similar social class, and similar age as the captain. Darwin noted that the plants and animals of South America were very distinct from those of Europe
The origin of the fauna of the Galapagos, 900 km west of the South American coast, especially puzzled Darwin. On further study after his voyage, Darwin noted that while most of the animal species on the Galapagos lived nowhere else, they resembled species living on the South American mainland. It seemed that the islands had been colonized by plants and animals from the mainland that had then diversified on the different islands
Show Campbell videos!!!
Darwin noted that the plants and animals of South America were very distinct from those of Europe. Organisms from temperate regions of South America were more similar to those from the tropics of South America than to those from temperate regions of Europe. Further, South American fossils more closely resembled modern species from that continent than those from Europe.
Theodosius Dobzhansky: Integrating Genetics and Evolution Theodosius Dobzhansky, a Russian geneticist who moved to the United States, provided laboratory evidence for natural selection and variation where previously there had been only field observation. Dobzhansky's work with Drosophila, or fruit flies, provided new evidence that supported Darwin's theory that natural selection, acting on genetic variation in populations, is a driving force in evolution.
Darwin noted that the plants and animals of South America were very distinct from those of Europe. Organisms from temperate regions of South America were more similar to those from the tropics of South America than to those from temperate regions of Europe. Further, South American fossils more closely resembled modern species from that continent than those from Europe.