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Evolution
and
Natural
Selection
2009
On the left page
Where is the
animal found?
What does the
animal look like?
What does the
animal eat?
Connection between adaptations & habitat.
What causes populations to
change over time?
On the left page think of 3
possible answers to this
question.
1.
2.
3.
Evolution…
Charles
Darwin
Alfred R.
Wallace
Darwin’s 5 year Voyage
On the left
page:
Why do
you think
that Darwin
Finches
have
different
beaks?
Darwin’s Theory of Natural Selection:
There is potential for
rapid reproduction.
Resources are limited and
population size is constant.
Organisms must compete for
survival and reproduction.
This is
Natural
Selection
This is
Evolution
There is variety in body
structures and behaviors.
Usually, the best adapted
organisms survive and leave
the most offspring.
The genetic makeup of the
population changes over time,
due to natural selection.
Some variability can be
passed to the offspring.
Evolution Needs:
Time:
– Takes a long time for organisms to evolve.
Variation:
– Need different looking and acting organisms in a
population- based on genes.
Competition:
– Organisms must compete with one another– there
cannot be enough space, food, mates, for everyone!
Different Success Rates:
– Different individuals must be more
or less successful than one another
in passing on their genes
(in offspring).
Stabilizing Selection
Center are the only
ones to reproduce
Individuals look more
similar over time
Less variation in new
population.
Directional Selection
Just one side
reproduces
Population looks
different over time
Same amount of
variation in new
population.
Peppered moth lab
Peppered Moth Lab
Disruptive Selection
Ends are the only ones
to reproduce
Produces 2 separate
phenotypes over time
More variation in new
population.
What environmental conditions could
cause populations to change?
Describe the
change that
had to
happen to
create the
two mice
species
shown in the
bottom
picture.
Geographic Isolation
Geographic Isolation
CAUSES Allopatric
Speciation.
This is when species
evolve as a result of
being separated from
each other.
Being in two different
environments causes
the species to adapt
in different ways.
How are New Species
Maintained?
Quick write:
Think of as many
reasons why tigers
and lions don’t make
ligers in nature –
without human
interference
Reproductive Isolation
Temporal- Breed in different
seasons, time of day
Behavioral- Courtship differs:
not attractive
Anatomical (Reproductive)
Parts don’t match any more
Gametic (Reproductive)
Zygotes die or infertile offspring
On the left- give an example of one
How do we study
evolution?
On the left side of your notebook, list 3
pieces of EVIDENCE that we can LOOK at
to see that evolution occurs.
1.
2.
3.
Similar Development
?
?
?
?
Homologous
Structures:
structures that
look the same
due to…
Divergent
Evolution:
from a
common
ancestor
Analogous Structures: structures
that look the same due to…
Convergent Evolution due to the
need to
adapt to
similar
environments
On left side: Double
bubble of analogous and
homologous structures
Similar fossils were found in geographically
isolated locations
On the left, where do you think we have
found similar fossils that demonstrate
not only that all the continents were
stuck together in the past but also that
we have evolved over time?
Fossil Evidence
Fossil Record- The chronicle
(record) of evolution over
millions of years of geological
time that is demonstrated by the
order in which the fossils appear
in rock stratus.
Microevolution
• Small genetic changes in a
population
• Change in frequency of a single
allele due to
selection
Macroevolution
• Large-scale changes in
organisms
On the left side:
create a Venn
diagram that
compares
microevolution to
macroevolution