Download EvolutionS7L5a

WARM UP- Please get a white sheet from the tray
on my stool- there is space for your warm up!
IN YOUR OWN WORDS…
1. WHAT DOES ADAPTATION MEAN?
2. WHAT IS NATURAL SELECTION?
Evolution
What’s the
Standard?
S7L5. Students will examine the evolution of living
organisms through inherited characteristics that promote
survival of organisms and the survival of successive
generations of their offspring.
a. Explain that physical characteristics of organisms have changed
over successive generations (e.g. Darwin’s finches and peppered
moths of Manchester).
Charles Darwin: Who is this guy?
Video Clip
Similarities and Differences
Checkpoint: How did
Darwin think plants and
animals had originally come
to the Galapagos Islands?
Answer: Perhaps they had
been blown out to sea or set
adrift on a fallen log.
Adaptations
What is an Adaptation? An adaptation is a
trait that helps an organism adjust to its
environment, survive and reproduce.
Adaptation: Elephant
(Video Clip)
Adaptation: Giraffe
Checkpoint: What type of adaptations allows giraffes to feed on a diet
of leaves from treetops? (LEMARC– BEFORE DARWIN)
Answer:
The body
structure of the
giraffe has
adapted over
time.
Evolution
What is Evolution? Darwin
believed that species
changed over time
becoming better adapted to
their environment. This
process is slow and takes
many generations.
Evolution
What makes an idea a Theory? It is well tested
and explains many observations.
How does a Theory different from a fact? A
fact is a specific observation, known to be
true; a Theory is a broad concept, thought to
be true because it explains many facts.
Natural Selection
What is Natural Selection? Natural selection is
the process by which individuals that are better
adapted to their environment are more likely to
survive and reproduce than other members of
the same species.
Survival of the fittest!
Who's Going
to Survive?
Natural Selection
• Video Clip
Natural Selection
There are several factors that Darwin
identified that affect the process of natural
selection:
• Overproduction of offspring
• Competition
• Variations
Overproduction
Competition
Natural
Selection
Variation
Overproduction
Most species produce
far more offspring
than can possibly
survive.
Competition
Competition is the
struggle between
organisms for the
limited resources in a
habitat.
Variation
Variation is any
difference
between
individuals of
the same
species.
Natural Selection: Examples
Are these two butterflies the same species?
These are the Monarch and Viceroy butterflies.
The Monarch on the left is poisonous and the Viceroy is not.
Question: Why would it be beneficial for the Viceroy to look like the
Monarch?
Natural Selection: Examples
Checkpoint: A species of hare
(rabbit) that is found in a cold
tundra environment. How are
oversized feet an advantage to
the Arctic Hare?
Natural Selection: Examples
How many moths do you see?
From 1 species to 14 species…
Warbler finch
Cactus finch
Woodpecker finch
Sharp-beaked finch
Small
insectivorous
tree finch
Large
insectivorous
tree finch
Small
ground
finch
Cactus
eater
Insect eaters
Medium
ground
finch
Seed eaters
Vegetarian
tree finch
variation
Bud eater
natural selection for best
survival & reproduction
Large
ground
finch
How Do New Species Form?
A new species
might form when
a group of
individuals
remains
separated from
the rest of its
species long
enough to evolve
different traits.
How Do New Species Form?
How Do New Species
Form?
Have the
Kaibab
Squirrel and
the Abert
Squirrel been
isolated long
enough to
become a
new species?
An example of Evolution through
Gene Flow
An example of Evolution through
Genetic Drift