December 27th, 1831: begins the trip around the world September 15th, 1835: the ship Beagle arrives at the Galapagos Islands Galapagos Islands.

December 27th, 1831: begins the trip around the world

September 15th, 1835: the ship Beagle arrives at the Galapagos Islands

Galapagos Islands

• He observes nature

• He draws animals and plants

• He keeps a diary

"I picked twenty-six species of land birds, all peculiar to the archipelago and absent elsewhere ... among others ... three species of mockingbirds, a form highly characteristic of America. The other land birds form a most singular group of finches, related to each other for the structure of the bill, short tail, body shape and plumage, of which there are thirteen species. All these species are details of this archipelago ... "

Charles Darwin is 26 years old

The birds observed by Darwin were similar, but they had some different features: Darwin counted 13 or 14 different types of finches

These types of finches lived on different islands (arid or with dense vegetation) or fed on different kinds of food (wheat, fruits, insects)

and not interbreeding: they BELONGED TO DIFFERENT SPECIES

In Biology, observing the FORMS helps to understand the FUNCTIONS

What’s the function of the different beaks?

pliers diagonal high-power

Pointed forceps

Strong clamps

Diagonal high-power pliers

Singing finch

Tree - finch

Large arboricolous finch

Pick up insects

Crush nuts

Eat fruits

•climate (temperature, humidity)

•food available (fruits, seeds, insects, fish, other animals)

•presence of other animals (predators, competitors)

ADAPTATION to the environment does not happen in one lifespan: it requires many GENERATIONS (eg 10, 20 or 100 generations)

For example, if the appearance of a new adaptation takes 20 generations:

Species Duration of 1 Generation x Number of Generation Time for a new Adaptation

Bird1 year x 20 20 years

Man25 years x 20 500 years

Microorganism 30 minutes x 20 10 hours

Each animal has got characters (i.e. features) suitable for:

But how does the mechanism of adaptation work?

CHIP

DALE(they are twins)

After flying for a long time in the same flock, they stop on different islands of the

Galapagos archipelago

Island 1: The sea is full of fish and the land is rich in fruit trees

Island 2: The sea is not very full of fish and on the ground there are plenty of corn and insects