History of Darwin

In 1831, Charles Darwin set sail on the HMS Beagle on a 5 year voyage around the world. He served as a naturalist (scientist who studies nature), and kept detailed notes of his findings. On the Galapagos Islands, Darwin noticed that the finches on one island were similar, but not identical to the finches on another island.

History of Darwin

The large ground finch has a heavy, strong beak for cracking large seeds.

The cactus finch has a tough beak that is good for eating cactus and nectar.

The warbler finch has a small, pointed beak - good for poking into cracks to get small insects.

History of DarwinWhy are the finches different on each island?

Start with the parent generation of finches. The parents have several baby finches. Some of them have larger beaks, some of them have smaller beaks, just like the pea plants (some are tall, some are short.)

Each island has a different food supply.Island #1: only has big, hard seeds. Which babies will do the best on island #1?

History of DarwinIsland #2 has no seeds, but has lots of insects

who like to hide in cracks in rocks and logs.

Which babies do you think would do best on island #2?

On island #1, the small beak babies would die, leaving only big-beaked finches. When those big-beaked finches have babies, what kind of babies do you think they will have?

History of DarwinOn island #2, the small-beaked babies would

thrive, and the big-beaked finches would die.What kind of beaks will the the babies of the

small-beaked finches have?

On each island, we see a change in the population of finches because of the difference in available food.

What happens to the “big-beak” genes on island #2 with the insects?

History of Darwin What happens to the “small-beak” genes on island #1

where the only food are the large seeds?

On both islands:Nature has selected the best beak.

“Natural Selection:” a process where animals (or plants) with favorable traits survive, and animals without those traits die.

“Survival of the fittest:” those who are the strongest, or best equipped for the environment survive. They pass their genes down to their offspring.

What is Natural Selection? Before natural selection takes place, dogs have lots of

genetic variety. Some of them are big, some are small. Some are faster, some are better diggers, etc…

What is Natural Selection? Before natural selection takes place, dogs have lots of

genetic variety. Some of them are big, some are small. Some are faster, some are better diggers, etc…Some of them are born with thick fur, some are born with

short, thin hair.

What is Natural Selection? Before natural selection takes place, dogs have lots of

genetic variety. Some of them are big, some are small. Some are faster, some are better diggers, etc…Some of them are born with thick fur, some are born with

short, thin hair. The population of dogs move to a place where it is much

colder.

What is Natural Selection? Before natural selection takes place, dogs have lots of

genetic variety. Some of them are big, some are small. Some are faster, some are better diggers, etc…Some of them are born with thick fur, some are born with

short, thin hair. The population of dogs moves to a place where it is much

colder. What will happen to the dogs with short, thin hair?

What is Natural Selection? Before natural selection takes place, dogs have lots of

genetic variety. Some of them are big, some are small. Some are faster, some are better diggers, etc…Some of them are born with thick fur, some are born with

short, thin hair. The population of dogs moves to a place where it is much

colder.What will happen to the dogs with short, thin hair?Which dogs are “naturally selected” to carry on their genes

to their puppies?

What is Natural Selection? Before natural selection takes place, dogs have lots of

genetic variety. Some of them are big, some are small. Some are faster, some are better diggers, etc…Some of them are born with thick fur, some are born with

short, thin hair. The population of dogs moves to a place where it is much

colder. What will happen to the dogs with short, thin hair?Which dogs are “naturally selected” to carry on their genes

to their puppies?

Which gene is passed on, and which gene is lost?

What is Natural Selection?Note:

They are now adapted to their environment.

What is Natural Selection?This has

occurred through natural selection.

What is Natural Selection?There have

been no new genes added.

Genes have been lost.

What is Natural Selection?The dogs are

less able to adapt to future evironmental changes. If the climate were to become hot, there is no genetic information for short hair, so the dogs would probably overheat.

What is Natural Selection?So we see that

natural selection is not an information-gaining process, but an information-losing process.

Natural selection is different than large-scale evolution.

Large Scale Evolution:

Textbook’s definition: Evolution is the process by which populations accumulate inherited changes over time.

The theory of evolution states that all life arose from a single cell over 3.7 billion years ago.