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Day 13 October 10th Chapter 8
How did the second exam go?
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Chapter 8: Evolution and Natural Selection
Darwins dangerous idea: evolution by natural selection
Lectures by Mark Manteuffel, St. Louis Community College ; Clicker Questions by Kristen Curran, University of Wisconsin-Whitewater
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Evolution in Action
8.1 We can see evolution occurright before us. Therefore,evolution is a scientific process.
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Could you breed fruitflies who could livelonger than 20 hours
on average?
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Populations
are studied
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When these eggs hatch, do you think theflies in this new generation will live longer
than 20 hours without food?
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What happened?
Evolution
a genetic change in the population
Natural selection the consequence of certain individual organisms in
a population being born with characteristics thatenable them to survive better and reproduce more
than the offspring of other individuals in thepopulation
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Does evolution occur?
The answer is an unambiguous:YES.
We can watch it happen in the labwhenever we want.
Recall from our discussion of the scientific method
that for an experiments results to be valid, they
must be reproducible.
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Experiments in Evolution
Dogs?
Rabbits?
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In Nature -
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Why are camels a successful species?
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Evolution
How does evolution occur?
What types of changes can evolutioncause in a population?
Five primary lines of evidence
Evolution by natural selection
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Darwins Journey to an Idea
8.2 Before Darwin, most peoplebelieved that all specieshad beencreated separately and wereunchanging.
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Button started the debate by suggesting the Earth
had to be at least 75,000 years old!
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Jean-Baptiste Lamarck
Biologist, early 1800s
Living species might change over time.
(Was wrong about the mechanism - he thought that change came about
through the use or disuse of features)
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Charles Lyell
Geologist
1830 bookPrinciples of Geology Geological forces had shaped the earth and were
continuing to do so.
Gradual but constant change
This idea that the physical features of the earth were constantly changing would most
closely parallel Darwins idea that the living species of the earth, too, were gradually
but constantlychanging.
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We know the Earth is constantly
changing
Fossils of shells have been found high in theAndes Mountains
Forest fires wipe out entire species of plants and
animals. Rivers flow, and carve out rock, creating two
distinct shores, where different species live.
Lakes dry up, killing all marine life inside.
Pollution and Toxic spills kill organisms.
Volcanoes.
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In the 1790s, Georges Cuvier began to explore the bottoms
of coal and slate mines and found fossils
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Why were fossils such a problem for
people at that time?
This was highly troubling for people at the
time.
http://www.bspcn.com/2009/04/03/11-extinct-animals-that-have-been-photographed-alive/
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Extinction
five mass extinctions on earth, and four in thelast 3.5 billion years - many species havedisappeared in a relatively short period of
geological time. The "Great Dying" about 250 million years ago,
which is estimated to have killed 90% of speciesexisting at the time.
Most extinctions have occurred naturally, withouthuman intervention: it is estimated that 99.9% ofall species that have ever existed are now extinct.
http://en.wikipedia.org/wiki/Permian%E2%80%93Triassic_extinction_eventhttp://en.wikipedia.org/wiki/Permian%E2%80%93Triassic_extinction_event8/3/2019 Day 13 October 10th Chapter 8 Scribd
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8.3 A job on a round-the-world surveyship allowed Darwin to indulge and
advance his love of nature.
Age 16, University of Edinburgh, medical studies
Studied theology at Cambridge University
His real love: study of nature
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Found that he HATED sea
travel
Spent as much time on
shore as possible
Collected fossils and
specimen to bring back to
England
Felt like he was on
permanent vacation
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8.4 Observing geographic similarities anddifferences among fossils and living plants
and animals, Darwin developed a theory ofevolution.
Lyells Principles of Geology
The Galapagos Islands
How could he explain finding marine fossils high in the Andes Mountains,
hundreds of miles from the nearest ocean?
The idea that the earth was an ever-changing planet was seeping into Darwins
mind.
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The Galapagos Islands
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July 1998 (I was a junior in college)