Unit 3 -EVOLUTION:CHANGE ACROSS TIME
Explaining the diversity of life and patterns of change across time.
Why does the theory of evolution exist?
1. The fossil record shows us a history of the organisms that once
lived on earth, but are no longer alive
2. The fossil record also shows that most organisms alive today,
were not alive in the geologic past, but appear similar to those that
are now extinct.
WHERE DID THE THEORY OF EVOLUTION COME FROM?
The theory of evolution was created in response to observations &
discoveries that were not explained by current beliefs:
A.
1.
B.
In the early 1800’s, Thomas Jefferson (yes, THAT Thomas
Jefferson) collected fossils, and wrote of marine fossils found on
top of mountains in Virginia.
He further cited evidence of fossils of marine organisms found in
the Andes Mountains of South America on mountaintops some
15,000’ above sea level.
Early Explanations of Evolution
Charles Darwin is credited as explaining the modern theory of
evolution, however he was not the first.
Theory of Acquired Characteristics
A.
B.
C.
D.
E.
For example, Lamarck
believed that giraffe’s
necks became longer
as they stretched for
food and that trait was
passed on the
offspring.
Today, we know that the theory of acquired characteristics is not
correct.
If it were the case, children of body builders would be born big and
buff like their parents and not need to work out. (for example).
Characteristics that are found within our genes are the only ones that
can be passed from generation to generation.
WHAT IS “EVOLUTION”
This misconception exists that evolution means that “humans came
from monkeys”.
The accurate definition is:
1.
a.
How is evolution possible?
Evolution is explained by four central points:
1.
2.
3.
4.
What is “Natural Selection”?
We all have heard Natural Selection summarized as “The Survival of
the Fittest”.
This simply means that the organisms with the characteristics that
make them more likely to survive and reproduce will survive and
reproduce.
Thus, the genes in the parents for those traits will be passed on to
future generations, increasing the number of individuals that have
the “good” trait.
How Does Natural Selection Work?
1.
2.
3.
4.
5.
Point #1: All Species Have Genetic Variation
1.
2.
3.
Point #2: The Environment Presents Challenges to Survival
The environment places many stresses and challenges on
individuals
1.
2.
3.
4.
5.
Point #3: Overproduction of Offspring.
1.
2.
Points #4 & 5: Increase of the beneficial characteristic over
Time
1.
2.
3.
4.
WHAT CONTROLS EVOLUTION?
The environment controls the speed and direction of evolution.
1.
2.
3.
How Evolution Looks
Over Generations of Time.