Transcript Evolution Powerpoint

AND NATURAL SELECTION
Before we begin…
EVOLUTION is a
topic that might
be controversial
with your family.
That’s okay.
• Let’s call it
“CHANGE OVER
TIME”.
• There’s many ways that
populations can change
over time….
• Natural selection…. Those
organisms well equip to
survive will pass on trats
• There’s artificial
selection... people (instead of
nature) select which organisms
get to reproduce
• …And sexual selection...
• EVOLUTION….
• Refers to the process in which
populations gradually change over
time.
• CHARLES DARWIN…
• Developed a theory of how evolution
takes place.
It is a result of complex interactions between
environment and organisms over many years.
• There is variation
in traits.
For example, some
beetles are green
and some are
brown. Sometimes
a result of
mutations.
• There is overproduction.
Since the environment
can't support unlimited
population growth, not
all individuals get to
reproduce to their full
potential. In this
example, green beetles
tend to get eaten by
birds and survive to
reproduce less often
than brown beetles do.
• There is adaptation and
selection.
The surviving brown
beetles have brown
baby beetles because
this trait has a genetic
basis. Those with the
most advantageous
traits are more likely to
survive and reproduce.
• End result:
The more advantageous
trait, brown coloration,
which allows the beetle
to have more offspring,
becomes more common
in the population. If this
process continues,
eventually, all
individuals in the
population will be
brown.
SLOW
DOWN UP
THERE!
I’M THE
FASTEST!
What would happen if we combined these two
ideas
?
Variation
from
Sexual
Reproducti
on
+
Limiting
Factors
THE SLOWEST
OF THE HERD
GETS EATEN
THE FASTEST OF
THE HERD
SURVIVE AND
PASS ON TRAITS
TO OFFSPRING
And the population changes to include
much faster buffalo over time!