Download The Theory of Evolution

Evolution
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Intro to Evolution
Essential Questions
1. What is evolution?
2. Isn’t evolution just a theory that remains
unproven?
3. Who is Charles Darwin?
4. What is natural selection and how does it
work?
5. What are the requirements for natural
selection?
6. What is an adaptation?
Evolution: the gradual change in a species through
adaptations over time
-All living species are the modified descendants of
earlier species
-All modern species share a common ancestor in
the distant past
-Evolution explains why
there is so much diversity
among Earth’s 5 million
living species
-“Nothing in biology makes
sense except in the light of
evolution.”
-Theodosius Dobzhansky,
evolutionary biologist
-Evolution ties together
the facts generated by the
fields of geology,
paleontology, biology,
biochemistry, and more.
-Evolution explains why
there is so much diversity
among Earth’s 5 million
living species
-“Nothing in biology makes
sense except in the light of
evolution.”
-Theodosius Dobzhansky,
evolutionary biologist
-Evolution ties together
the facts generated by the
fields of geology,
paleontology, biology,
biochemistry, and more.
Charles Darwin:
-English scientist
-Originally published
the theory of evolution
(1859)
-Gathered evidence in
the Galapagos Islands
Alfred Russell
Wallace:
-English scientist
-Independently
conceived the same idea
as Darwin
-Gathered evidence in
the Malay Archipelago
Scientists of Evolution:
Not just Darwin!
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Greek philosophers Anaximander, Empedocles, and Aristotle
John Ray (England 1627)
Carl Linnaeus (Sweeden 1707)
Pierre Louis Maupertuis (France 1698)
Georges-Louis Buffon (France 1707)
Jean-Baptiste Lamarck (1744)
William Paley (England 1743)
Charles Darwin (England 1809)
Alfred Russell Wallace (England 1823)
Thomas Henry Huxley (England 1825)
Gregor Mendel (Germany 1822)
Hugo de Vries (Dutch 1848)
Ronald Fisher (England 1890)
Theodosius Dobzhansky (Ukraine 1900)
Now, evolutionary research is being carried out in most major American
colleges and universities!
Evolution is not just a “theory”- it’s a
scientific theory
• Scientific theory: a rigorously tested explanation
for an observation that has never been proven
wrong
• As science advances, data from a range of
scientific disciplines (geology, physics, chemistry,
molecular biology) have not only supported
evolutionary theory, but expanded it
• Theory of evolution = theory of gravity
What is evolution?
• Evolution is the biological model for the
history of life on earth
• Small modifications occur within the DNA of
each generation; these genetic changes can
affect how the creature interacts with its
environment
• Over time, the accumulation of these genetic
changes can alter the characteristics of the
whole population, creating a new species
• Natural selection: the mechanism by which
evolution takes place
• Natural selection: the mechanism by which
evolution takes place
• Natural selection is the idea that those
organisms who are more fit to survive in their
environment will pass on their genes to future
generations
• Natural selection: the mechanism by which
evolution takes place
• Natural selection is the idea that those
organisms who are more fit to survive in their
environment will pass on their genes to future
generations
• Over time, the
population will begin to
resemble the
organisms that are more
fit
• Similarly, harmful traits are quickly eradicated as
individuals that possess them are less likely to
reproduce.
• Natural selection works to create a population that is
highly suited to its environment and can adapt over
time to environmental changes.
Requirements for Natural Selection
1. Variation within one trait in a population
These variations may involve body size, hair
color, facial markings, voice properties, or
number of offspring.
Requirements for Natural Selection
2. The trait must be heritable, not created by
environmental conditions
Heritable
Not Heritable
Requirements for Natural Selection
3. The population must have a high growth rate
so that traits will be passed on frequently
enough
Requirements for Natural Selection
4. The trait must affect how an organism can or
cannot compete for resources.
Individuals possessing traits well suited for the
struggle for local resources will contribute more
offspring to the next generation.
Requirements for Natural Selection
In order for natural selection to operate on a trait,
the trait must:
1. Possess variation
2. Be heritable
3. Create an advantage in the competition for
resources.
If one of these requirements does not occur, then
the trait does not experience natural selection.
• Adaptation: a trait that gives an organism an
advantage when it comes to surviving and
reproducing
• Adaptation: a trait that gives an organism an
advantage when it comes to surviving and
reproducing
Intro to Evolution
Essential Questions
1. What is evolution?
2. Isn’t evolution just a theory that remains
unproven?
3. Who is Charles Darwin?
4. What is natural selection and how does it
work?
5. What are the requirements for natural
selection?
6. What is an adaptation?
2. Isn't evolution just a theory that
remains unproven?
-In science, a theory is a rigorously tested statement of
general principles that explains observable and recorded
aspects of the world. A scientific theory therefore describes a
higher level of understanding that ties "facts" together. A
scientific theory stands until proven wrong -- it is never
proven correct.
-The Darwinian theory of evolution has withstood the test of
time and thousands of scientific experiments; nothing has
disproved it since Darwin first proposed it more than 150
years ago. Indeed, many scientific advances, in a range of
scientific disciplines including physics, geology, chemistry, and
molecular biology, have supported, refined, and expanded
evolutionary theory far beyond anything Darwin could have
imagined.