Transcript The Human Endocrine System

Natural Selection
How evolution works
By: Jenny Kong
Smart Start
 Write
down a description of a physical
characteristic of an animal (or plant) that
helps it to survive in its environment.
What do you think of adaptation?
Three friends were arguing about what would
happen if a population of rabbits from a
warm, southern climate were moved to a
cold, northern climate. This is what they
said:
Bernie – “I think all of the rabbits will try to
adapt to the change.”
Leo – “I think most of the rabbits will try to
adapt to the change.”
Phoebe – “I think few or none of the rabbits
will try to adapt to the change.
Which person do you most agree with and
why? Discuss your ideas with your partner.
Video 4: How Does Evolution Really Work?
 Describe
the process of natural selection
 How does natural selection affect
hummingbird populations?
Natural Selection is the
way nature acts to
select for an
organism’s traits.
Members of a population
have variations
(differences in traits)
that make certain
individuals better
adapted to survive.
(ex. size, color,
structure
Individuals that are best
suited, or adapted,
to the environment
are more likely to
survive.
If they survive, they
reproduce and the
traits that help them
survive are passed
on to their offspring.
Examples of modern
evolution:
A. Peppered moth –
Pollution causes
tree barks to
become dark.
Some moths are
dark-colored and
survive  there is
an increase of
dark moths.
B. Pesticides kill
insects. Some
insects have a
mutation that
makes them
resistant to
pesticides.
They survive
and reproduce.
C. Antibiotics – Some bacteria are resistant to
antibiotics. They survive & reproduce,
increasing the frequency of antibiotic
resistance.