Download Which rabbit is best adapted?

The Theory of Natural Selection
No. The white rabbits died. Since the green survived
Did
therabbits
white
rabbits
turn
green?
better
they
reproduced
more.
Which
are
best adapted
(more
likely to survive and reproduce)?
Artificial Selection
• Humans have shown
that breeding can
cause changes over
time
– Dogs, Crops,
Livestock
• Humans (not nature)
have selected
desirable traits
• What’s the point?
Proves that breeding
can lead to change
over a period of time
Pigeons have been bred to enhance
tail feathers….breast feathers…etc…
Wild mustard has been bred by farmers
into numerous other foods
Dog traits have been selected by breeders for
centuries to enhance certain traits.
These kittens
have variations
Not all these
wildebeest will
survive
• Four factors:
1) Overpopulation: more offspring are born than can survive
2) Variation: individuals of a population have differences
3) Adaptation: Some variations allow a better chance of
survival
4) Over time, those with advantages make up most of the
population
The Myth
Individuals don’t grow
something because
they need it.
Individuals don’t evolve.
Which rabbit is best adapted?
Do the dark rabbits turn white? No! They get eaten.
Struggle for Survival
Predation
Competition
Disease
Clean water
Shelter
Acts of Nature
• Populations do not grow unchecked
• “Limiting Factors” prevent overpopulation
• Fitness: measure of the ability to survive & produce
more offspring
New environments are
continually created.
What happens to life that
has favorable traits to
survive a changing Earth?
They reproduce and pass
those advantages to their
offspring.
Changing Environments
The Colorado river is carving a “Grand Canyon”.
Changing Environments
This dry valley in Egypt was once an ocean. How do we know this?
Whale, fish, and other marine fossils have been discovered.
Changing Environments
Ever feel an Earthquake?
The giant plates of the Earth’s crust are moving and re-arranging.
Changing Environments
Fun Fact:
LA moves about
1.5inches north
every year.
is California’s
fault. is moving South.
The western plateHere
is moving
North…San
theAndreas
eastern plate
So what happens when environments change?
Year 1 Background
Year 10 Background
Those best adapted survive and reproduce.
• Constant creation of
chemicals for human use
is eliminating the “unfit”
organisms
– Ex: Antibiotics
eliminating unfit bacteria
Alexander
Fleming
discovered the
first
antibiotic…
penicillin
• Constant creation of
chemicals for human use
is eliminating the “unfit”
organisms
When
The antibiotics
infected with
are absorbed
a bacteria,into
we the
take
antibiotics.
bacteria.
– Ex: Antibiotics
eliminating unfit bacteria
Bacteria A is more likely to survive and _________________.
REPRODUCE
antibiotic
antibiotic
antibiotic
antibiotic
Bacteria A
Bacteria B
antibiotic
antibiotic
Bacteria A
antibiotic
Bacteria A has genes to create
enzymes that destroy the antibiotic
antibiotic
Bacteria B does not have the genes to
make the enzymes to destroy the antibiotic
• Constant creation of
chemicals for human use
is eliminating the “unfit”
organisms
Notice there is no bacteria growth
30
seconds:
Discuss
with
The
5
white
discs
have
treated
This
Petri
dish
has
bacteria
surrounding kanamycin been
and growing
your
with
antibiotics.
on 5neighbor
it.different
The bacteria
appear
amoxycillin.
This
means
thatas the
Ifbrown
you were
infected
with
this
smears
on
the
background
of
kanamycin and amoxycillin are killing
bacteria, which
antibiotics
the
Petri
dish.
the bacteria.
could be used to treat your
infection?
– Ex: Antibiotics
eliminating unfit bacteria
penicillin
ampicillin
amoxycillin
kanamycin
tetracyclin
• Constant creation of
chemicals for human use
is eliminating the “unfit”
organisms
– Ex: Antibiotics
eliminating unfit bacteria
– Ex: Pesticides
eliminating unfit pests
• Constant creation of
chemicals for human use
is eliminating the “unfit”
organisms
– Ex: Antibiotics
eliminating unfit bacteria
– Ex: Pesticides
eliminating unfit pests
• Constant creation of
chemicals for human use
is eliminating the “unfit”
organisms
Some “pests” are able to resist the
pesticides and survive. They will
reproduce with others who are
resistant. Over time, the entire
population is resistant.
– Ex: Antibiotics
eliminating unfit bacteria
– Ex: Pesticides
eliminating unfit pests
Pesticides pesticides pesticides pesticides pesticides pesticides
• Constant creation of
chemicals for human use
is eliminating the “unfit”
organisms
– Ex: Antibiotics
eliminating unfit bacteria
– Ex: Pesticides
eliminating unfit pests
– Ex: Antivirals…
– Ex: Fungicides…
• This is natural selection!
– Allows resistant to
survive and reproduce
#6: Why Does Evolution Matter Now?
Review
1)
2)
3)
4)
What is artificial selection?
What is natural selection? (Describe the 4 factors)
How does natural selection lead to population changes?
Explain why scientists believe the Earth’s environments have
been changing for millions of years.
5) Why don’t populations (such as deer) continue to grow
unchecked?