Evolution
https://vle.whs.bucks.sch.uk/course/
view.php?id=5741
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
Isn’t Evolution a Theory?
• Evolution is a scientific theory
– Scientific theories are supported by overwhelming data
– In informal speech, when we use the word “theory,” we
actually mean “hypothesis”
• Evolution is NOT a theory in the colloquial use of the term
-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
-As science advances, data
from a range of scientific
disciplines (geology, physics,
chemistry, molecular biology)
have not only supported
evolutionary theory, but
expanded it
-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
-As science advances, data
from a range of scientific
disciplines (geology, physics,
chemistry, molecular biology)
have not only supported
evolutionary theory, but
expanded it
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!
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
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!
How does evolution work?
• Evolution is the biological model for similarity and
differences we observe in the species 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
Additional Vocab
• Paleontology: the study of fossils
• Strata: layers of rock
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?