Transcript Evolution & Natural Selection

Warm up: Organize folder and
pick papers up at front
ß Page 1-2: Table of Contents
ß Page 3-6: Warm up
ß Page 7: Gallery Walk Review (what we did
outside of classroom)
ß Page 8: Non-Mendelian Notes
ß Page 9: Mitosis Review Notes
ß Page 10: Mitosis vs. Meiosis Worksheet
Notes: Evolution & Natural
Selection
Evolution
ß What scientific explanation can account for
the diversity of life?
ß The answer is a collection of scientific facts,
observations, and hypotheses known as
evolutionary theory.
ß Evolution, or the change over time, is the
process by which modern organisms have
descended from ancient organisms.
Charles Darwin
Charles Darwin is the individual that has
contributed more to our understanding of
evolution than anyone.
His father was a wealthy doctor and wanted
Charles to become a doctor.
At age 16, he went to Medical
School.
In 1827, his father sent him to
become a priest.
In 1831, a friend asked him
to go on a ocean trip as
an unpaid naturalist on the HMS Beagle.
Lamark was a French naturalist who…
ß Claimed that organisms tend to be complex and perfect
and are therefore unchanging.
ß Use and disuse- Lamark thought that animals could
change their bodies by using them in new ways.
Example: animals could use front limbs as wings and
develop flight.
ß Inheritance of acquired traits- Lamark though that all
changes could be inherited. For example, if you life
weights, your children would inherit your muscles.
ß Lamark’s ideas are not scientifically accepted today!
Darwin’s Voyage on the HMS
Beagle
The purpose of the trip was to draw accurate maps
of the region. Darwin was to collect specimens
and document the plant and animal life.
Darwin’s original beliefs
Divine creation - each species was created
by God, unchanging and existing as it
was originally created.
On the voyage Charles made numerous
observations & collected evidence that
led him to propose a revolutionary
hypothesis about the way life changes
Darwin’s Finches
In the Galapogos Islands, Darwin observed
finches showed convincing evidence
that species evolve.
Darwin was struck by the fact that the animals of the
Galapagos Islands resembled those of the nearby
coast of South America.
He saw patterns of diversity & was intrigued by the
fact that so many plants and animals seemed
remarkably well suited to whatever environment
they inhabited.

Darwin hypothesized that ancestors of the
Galapagos Islands must have migrated to the island
and changed after they arrived.
That hypothesis, now supported by a huge body of
evidence, has become the Theory of Evolution.
Darwin published his book in 1844:
On the Origin of Species by Means of
Natural Selection.
In this book Darwin developed a scientific
hypothesis to explain how evolution occurs:
The Theory of Natural Selection.
Natural Selection – process by which
individuals that are better suited to their
environment survive and reproduce more
successfully (survival of the fittest)
Darwin’s Theory of Natural
Selection
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2.
3.
4.
5.
There is variation within any species
All organisms tend to over-reproduce
There is a struggle for survival
The fittest survive
The environment determines who is
the fittest
1. Variation exists within every
population
1. Ladybugs have different spots
1. Variation exists within
every population
2. Zebras all have
different stripes
2. All species tend to produce more
offspring than they can SUPPORT
3. Frog eggs
1. Turtle eggs
2. Insect
eggs
4. Baby
mice
3. There is a Struggle for
Survival
1. To eat
2. To drink
3. Territory
4. To mate
4. The fittest will survive
4. The fittest will survive
2. Healthy or sick horse?
1. Weak or strong woman?
5. Nature (the environment) will
determine which organism is the
fittest to Survive
1. long neck giraffes survive over short neck giraffes.
Evidence of Natural Selection in
our lifetime
The Peppered Moth in England
Before the industrial
revolution
After the industrial
revolution
Explanation for the peppered moth
There was variation in the moth population to
begin with, some were black and some were
white.
This variation was due to random mutations.
Before the industrial revolution, the bark of the
tree bark was white in color.
The white moths then were
easily camouflaged,
survived, and reproduced.
Black moths were rare.
After the industrial revolution, the trees
became covered in soot/pollution from all of
the factories and the trees turned black.
Now the black moth
were easily camouflaged,
survived, and reproduced.
White moths were rare.
How does the peppered moth
illustrate natural selection?
There was variation in the population to begin
with (some white, some black).
Moths tend to over-reproduce .
Therefore there is a struggle for survival.
The fittest (those that were camouflaged the
best) survived.
The environment determined which moths were
the most fit.
•Natural Selection produces changes in
POPULATIONS over time: NOT
INDIVIDUALS.
Natural Selection may lead to
Speciation
Speciation - the evolution of a
new species
The process of speciation
ß Geographic Isolation - when two
populations become isolated by a
geographic barrier.
Geographic Isolation
ßReproductive Isolation - Sometimes
when populations have been separated
for a long, long time, they become so
different that they can no longer breed
and produced fertile offspring.
Same species now, but may become two different ones.
1. Horse and Donkey = Mule
Mule is infertile (can’t have babies)
horse
mule
donkey
Lion and Tiger = Liger
Liger is often infertile (there have
been successful breedings)
2. The Kaibab and Abert Squirrels
Became reproductively isolated by huge mountains
3. Wood and Leopard Frogs
Wood frogs
Leopard frogs
Seem to be the same species, but they breed
at different times of the year.
ßSpeciation -When two populations
become so different that they can no
longer breed and produce fertile
offspring. They are then considered two
separate species.