Transcript Ch 16 Darwin`s Theory of Evolution

1 Apply Concepts How would Hutton and Lyell explain the
formation of the Grand Canyon
2 Review What is an acquired characteristic and what role
did Lamarck think they played in evolution
3 Review What is artificial selection
Infer Could artificial selection occur without inherited
variation- explain
4 Draw conclusions How did Malthus influence Darwin
Writing Imagine you are Malthus in the year 1798. Write
a newspaper article that explains your ideas about the
impact of a growing population on society and the
environment
CH 16 DARWIN’S THEORY OF EVOLUTION
16.2 Ideas that shaped Darwin’s Theory
Hutton and Geological Change
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Recognized the connections between geological
processes and geological features
Some rocks form very slowly, as sediments build up
and are squeezed into layers
Mountains, in turn, can be worn down by rain,
wind, heat, and cold
Earth is much older than a few thousand years.
Lyell’s Principles of Geology
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Uniformitarianism
 Idea
that the geological processes today are the same
ones that shaped Earth millions of years ago
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Lyell argued that Earth was much, much older than
a few thousand years.
An Ancient, Changing Earth
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Hutton and Lyell concluded that Earth is extremely
old and that the processes that changed Earth in
the past are the same processes that operate in
the present.
Helped Darwin
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Witnessed a earthquake that lifted a stretch of
shoreline 3 meters out of the sea with mussels and
other sea animals clinging to it
Darwin observed fossils of marine animals in
mountains thousands of feet above sea level.
Lamarck’s Evolutionary Hypotheses
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Organisms could change during their lifetimes by
selectively using or not using various parts of their
bodies
Individuals could pass these acquired traits on to
their offspring.
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Black-necked stilt could have acquired long legs
because it began to wade in deeper water looking
for food. As the bird tried to stay above the water’s
surface, its legs would grow a little longer
It acquired longer legs.
Darwin wasn’t the first to suggest species could
change over time
 His grandfather Erasmus
 Patrick Mathew came up with ideas
of Natural Selection in 1831
 Published in “Naval Timber and Arboriculture”
 “Anyhow one may be excused in not having
discovered the fact in a work on ‘Naval Timber’”
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 Darwin.
Evaluating Lamarck’s Hypotheses
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We know that Lamarck’s hypotheses were
incorrect in several ways
Organisms don’t “strive” to get better
Traits acquired by individuals during their lifetime
cannot be passed on to offspring
 Or
can they
 Bacteria and recombinant DNA.
Population Growth
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Malthus wrote on human overpopulation
The rate of population increase was greater than
the rate of food increase
 Eventually
there will be more humans than the
amount of room and food needed to support
everyone.
Helped Darwin
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Darwin applied this idea to his own data- most
species have a high reproductive potential (maple
trees and helicopters, fish laying thousands or
millions of eggs) but not all individuals reproduce
let alone survive.
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When Darwin realized that most organisms don’t
survive and reproduce, he wondered which
individuals survive…and why?
Artificial Selection
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Nature provides the variations, and humans select
those they want or find useful
Plant and animal breeders
Over time this would produce trees with even
bigger fruit and cows that gave even more milk.
Helped Darwin
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Darwin put artificial selection to the test by raising
and breeding plants and fancy pigeon varieties.
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Darwin had no idea how heredity worked or what
caused heritable variation
He did know that variation occurs in wild species
He recognized that natural variation provided the
raw material for evolution.