WHAT IS EVOLUTION?

EVOLUTION IS…• Change over

time

• Process by which modern organisms have descended from ancient organism

• THEORY!!

Simply stated

CREATIONISM

• Theory that life on Earth was formed by a divine being.

• Science vs. Faith (not mutually exclusive)

HUTTON & LYELLConcluded that the Earth is extremely old and that the processes that changed the Earth in the past are the same SLOW processes that operate in the present.

MALTHUSReasoned that if the human population grew unchecked, there wouldn’t be enough living space and food for everyone.

• Evolution by acquired traits• Organisms developed traits

during their lifetime .• Give those traits (big

muscles) to their offspring.• Example

• In reaching higher leaves giraffes stretch their necks & give the acquired longer neck to offspring.

• Not accepted as valid

LAMARCK

DARWIN’S VIEW OF EVOLUTION

Father of modern evolution theory

• Giraffes that already have long necks survive better.

• Leave more offspring who inherit their long necks.

• Believed in descent with modification.

• Wrote a book: The Origin of Species

DESCENT WITH MODIFICATION

• All species—living and extinct– are descended from ancient common ancestors.

• Over many generations, adaptations could cause successful species to evolve into new species making them better suited for their environment.

• Examples: tiger’s claws; colors, like those that make camouflage or mimicry possible; or physiological functions, like the way a plant carries out photosynthesis.

“SURVIVAL OF THE FITTEST”

• If you are better fit for your environment, you will survive.

• You will reproduce.• Over time, population will be

more like you.• Fitness: the ability to survive

and reproduce.

VOYAGE OF THE HMS BEAGLE

Stopped in Galapagos Islands

• 500 miles off coast of Ecuador

Many of Darwin’s observations made him wonder… Why?Many of Darwin’s observations made him wonder… Why?

DARWIN FOUND…MANY UNIQUE SPECIES

GALAPAGOS ISLANDS

Example: Finches• 13 species of finches• Found on different islands• Beak size and shape varied• Ate different food

Finches had adapted to best obtain food in their environment.

NATURAL SELECTION • Organisms with

variations well suited to the environment survive and leave more offspring at a fast rate.

• You have the genes to be successful in your environment or you don’t

• Variety already exists, some varieties better fit to environment than others.

NATURAL SELECTION

VARIETY IS THE SPICE OF LIFE…

Variation: differences between members of the same species

Cause of variation = mutations

Variation is important to survival!

Example: Peppered Moth

EXAMPLE:Which population of hares has a better chance of survival as a species?

Population A Population B

POPULATION B

Because it has more genetic variation than population A so there will be some individuals that are more fit if the environment were to change. Thus the species has a higher chance of survival.

TAKE HOME MESSAGE:Genetic variation increases a species’ chance of survival

Variation good survival

The selective breeding of domesticated plants and animals by man. Provides variations that humans find useful.

Example: Dog breeds, & flowers

ARTIFICIAL SELECTION