Download Why do organisms change? - Rabun County School District

Why do organisms change?
Natural Selection in Action
• The THEORY OF NATURAL SELECTION explains
how a population changes in response to its
environment.
• What are some of the factors that causes
changes in the environment?
Let’s Brainstorm
Changes in Population
Hunting
Ex. Elephants in
Uganda hunted for
ivory
Trophy buck
management
Resistance
Pesticides and antiobiotics
Competition
More colorful males attract
the females-peacocks
What about humans? How
do we pick mates?
Why can do some organisms like
insects and bacteria develop resistance
and change so quickly?
They have very short generation times.
Generation time is the period between the birth
of one generation and the birth of the next
generation.
Speciation-The formation of a new species as a
result of evolution
How do new
species form?
Separation
sepaated
Once separated
1. Canyon
2. Mountain Range
3. Lake
Adaptation
Division
The two groups may not
be able to interbreed
anymore.
Time and many
generations


Over many generations, th
separated groups may
evolve different sets of
traits.
If the environmental
conditions are different fo