Download Natural Selection

Unit 12
Adaptation & Natural
Selection
Pre-Assessment
1. A man becomes a fireman. While
working at his job, he grows strong and
his muscles get big due to the physical
work. When this man has children, can
we predict that they will also have big
muscles since their dad does? Why or
why not?
2. Describe/discuss an example of an
adaptation.
What is a trait?
A characteristic
that describes
an organism.
Where do we get
our traits?
DNA!
Genes!
Variation
• A distinct feature (trait), behavior, or
physiology of the organism that occurs to
individuals within a population or species
Population
• Members of the same species that live in the
same geographical area
• May be distinctly different than populations
living elsewhere, due to the spread of local
adaptations within a population
Adaptation
• A process by which a population becomes
better suited to its habitat
• A genetic variation that provides an advantage
to survive and reproduce
Examples of Adaptations
• Mimicry of leaves by insects
is an adaptation for evading
predators
• Echolocation in bats is an adaptation for
catching insects.
• A plant storing food
in the form of
a bulb
Examples of Adaptations
• Birds migrating to a different
geographical or climatic region
where food is more available
• A bear hibernating to survive
long periods of cold temperature
or reduced food supplies
• A walrus uses blubber to store energy and
keep warm
What trait keeps this organism safe?
Camouflage!
Camouflage allows
an organism to
blend in by changing
the pattern/color of
their skin.
What trait keeps this organism safe?
Barbs!
Barbs keep this
organism safe
from predators
that want to eat
it.
What trait attracts bees to this plant?
Color!
Scent!
Patterns!
Flowers look &
smell pretty to
attract bees!
Why do these bugs have different
mouthparts?
They are adapted to the
insect’s method for eating!
Natural Selection
• Process of selection whereby favorable traits
become more common and less favorable
traits become less common in following
generations
• Evolution results from natural selection acting
upon variation within a population
Natural Selection
• Environmental changes can influence natural
selection
• Individual organisms with advantageous traits
are more likely to survive and have offspring
Natural Selection
Factors that affect natural selection
• Overproduction of offspring in a species
• Competition between species
• Genetic variations within a population
Big Question
Why do these dogs look so different?
Selective Breeding!
Humans select the traits
they like & only bred dogs
that have those traits.
• After a few generations of
puppies, all the dogs they
own have those traits!