Natural Selection How evolution works By: Jenny Kong.

Natural SelectionNatural SelectionHow evolution worksHow evolution works

By: Jenny KongBy: Jenny Kong

Smart StartSmart Start

Write down a description of a physical Write down a description of a physical characteristic of an animal (or plant) that characteristic of an animal (or plant) that helps it to survive in its environment.helps it to survive in its environment.

What do you think of adaptation?What do you think of adaptation?Three friends were arguing about what would Three friends were arguing about what would

happen if a population of rabbits from a happen if a population of rabbits from a warm, southern climate were moved to a warm, southern climate were moved to a cold, northern climate. This is what they said:cold, northern climate. This is what they said:

BernieBernie – “I think all of the rabbits will try to – “I think all of the rabbits will try to adapt to the change.”adapt to the change.”

LeoLeo – “I think most of the rabbits will try to adapt – “I think most of the rabbits will try to adapt to the change.”to the change.”

PhoebePhoebe – “I think few or none of the rabbits will – “I think few or none of the rabbits will try to adapt to the change.try to adapt to the change.

Which person do you most agree with and why? Which person do you most agree with and why? Discuss your ideas with your partner. Discuss your ideas with your partner.

Video 4: How Does Evolution Really Work?Video 4: How Does Evolution Really Work?

Describe the process of natural selectionDescribe the process of natural selection How does natural selection affect How does natural selection affect

hummingbird populations?hummingbird populations?

Natural SelectionNatural Selection is the is the way nature acts to way nature acts to select for an select for an organism’s traits.organism’s traits.

Members of a population Members of a population have have variationsvariations (differences in traits) (differences in traits) that make certain that make certain individuals better individuals better adapted to survive. adapted to survive. (ex. size, color, (ex. size, color, structurestructure

Individuals that are best Individuals that are best suited, or suited, or adaptedadapted, to , to the environment are the environment are more likely to survive.more likely to survive.

If they survive, they If they survive, they reproducereproduce and the and the traits that help them traits that help them survive are passed on survive are passed on to their offspring.to their offspring.

Examples of modern Examples of modern evolution: evolution: A.A. Peppered mothPeppered moth – –

Pollution causes Pollution causes tree barks to tree barks to become dark. become dark. Some moths are Some moths are dark-colored and dark-colored and survive survive there is there is an increase of an increase of dark moths.dark moths.

B.B. PesticidesPesticides kill kill insects. Some insects. Some insects have a insects have a mutation that mutation that makes them makes them resistant to resistant to pesticides. pesticides. They survive They survive and reproduce.and reproduce.

C.C. AntibioticsAntibiotics – Some bacteria are resistant to – Some bacteria are resistant to antibiotics. They survive & reproduce, antibiotics. They survive & reproduce, increasing the frequency of antibiotic increasing the frequency of antibiotic resistance.resistance.