Unit 12Adaptation & Natural

Selection

Pre-Assessment1. 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 SelectionFactors 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!