Warm ups:1.We have many species currently living that are so rare or otherwise threatened that they may soon disappear.

What term is used to refer to these animals?

a. endangered b. exoticc. extinct d. Beloved

OBJECTIVE: You will be able to explain how natural

selection works

Natural Selection Notes

Natural Selection Notes

“How the changes in the environment can bring

about changes in species”

1. Artificial selection – breeding animals and plants for certain characteristics

2. Darwin explains evolution

a. 1858 Darwin writes “The Origin of Species”, explains evolution through the theory of NATURAL SELECTION.

b. Natural selection –individuals that are better adapted to their environment = more likely to survive and reproduce than other members of the same species. (“Survival of the Fittest”)

c. Four steps to natural selection!!

NATURAL SELECTIONStep 1: OVERPRODUCTION – each species

makes more offspring than will survive

NATURAL SELECTIONStep 2 – GENETIC VARIATION –

Any difference between individuals of the same species

- some traits help, some hurt them.

- Some variations are helpful = adaptation

Step 2 – GENETIC VARIATION

Not everyone is identicala. Different genes = different traits

b. Fast swimmers, better camouflage

NATURAL SELECTION

Step 3: STRUGGLE TO SURVIVE - COMPETITION

– A natural environment doesn’t have enough resources for everyone, so only some individuals survive to adulthood.

Step 3 - Competition: Usually indirect – no actual physical fights

Not enough food, not be able to escape from predators

Only strong organisms will survive long enough to reproduce

NATURAL SELECTIONStep 4: SUCCESSFUL REPRODUCTION

– the individuals that are well adapted to the environment are more likely to survive and reproduce. Their genes will be passed on.

**Over a long period of time, natural selection can lead to evolution.**

Peppered moth storyThe case of the English peppered moth is an

example of how human actions can affect natural selection. In the late 1700’s, most English peppered moths were light gray in color. The light-colored moths had an advantage over black peppered moths because birds could not see them against the light-gray trees. Natural selection favored the light colored moths over the black moths.

The industrial revolution began in England in the late 1700’s. People built factories to make cloth and other goods. Over time, smoke form the factories blackened the trunks of the trees Now the light-colored moths were easier to see than the black ones. As a result, birds caught more light-colored moths. Natural selection favored the black moths. By about 1850, almost all the peppered moths were black.

Before Industrial Revolution

After Industrial Revolution

The Heike or Oni-gani (“demon spirit” crab, Dorippe japonica), whose name derives from a Japanese legend. The pattern on its shell is thought to resemble the face of a Samurai warrior.

Natural or artificial selection? Intentional or accidental?

Sexual Selection (“Darwin’s headache”)

Archaeopteryx, discovered 1861

Exit Slip1. Give me an adaptation that rabbits have to

help them survive?

2. What is Natural Selection and who came up with this theory?

3. How does competition result in Natural Selection?

4. Give an example of an animal that we have changed through the process of Artificial Selection.