1. Animals depend on physical
features to:
obtain food
keep safe
build homes
withstand weather
attract mates.
2. Do not develop during an animal's life but over
many generations.
Examples:
shape of a bird's beak
number of fingers
color of the fur
thickness or thinness of fur
shape of the nose or ears
3. Defensive adaptations include:
Predator avoidance
Hiding and camouflage
Group defense
Fleeing
Signal
Warnings
4. Many organisms avoid predators by the use of
cryptic coloration.
A requirement of camouflage in many cases is
that the individual choose an appropriate
background.
5. Natural selection rests on three facts:
1. Organisms produce more offspring than can survive.
2. Individuals vary in their characteristics.
3. Many characteristics are inherited by offspring from
their parents.
6. • Some individuals will be better suited to their
environment
They will survive and reproduce
more successfully than individuals
without those characteristics.
• Future generations: contain more genes from
better-suited individuals.
• Result: characteristics will evolve over time to
resemble those of the better-suited ancestors.
7. Two Kinds:
White speckled moth
Black moth.
In early 1800’s dark form was very rare.
Dark form caused by dominant mutation that
occurs spontaneously.
9. Unpolluted Areas: trees are covered
in lichens and the light form of the
moth is hard to see.
In mid 1800’s air pollution in British
cities covered trees with soot.
In cities dark form became common
and light form rare.
10.
11. Inmid 1950’s pollution
controls were introduced in
Britain and frequency of the
black moth form has declined
since then.
