Timeline of Darwin’s lifeBorn 1809Study (Edinburgh and Cambridge) 1825-1831

Voyage of the Beagle 1831-1836Retired to Down 1842The Origin of Species 1859Died 1882

Not just an Evolutionist Not even a biologist to start withCollected beetles for funStudied geology more seriouslyConsidered himself a geologist

throughout the Beagle voyage and for some time after

Famous for working out how coral atolls are formed

An atoll is a ring-shaped coral reef, island, or series of islets. An atoll surrounds a body of water called a lagoon. Sometimes, atolls and lagoons protect a central island. Channels between islets connect a lagoon to the open ocean or sea.

His books (not just on evolution)Beagle voyageCoral reefsVolcanic islandsGeology of South

AmericaBarnaclesSpeciesMan

• Emotions• Climbing plants• Domestication• Cross and self

fertilization• Orchids• Worms• Autobiography

Contributor’s to Darwin’s thinking included:

Charles Lyell- Uniformitarianism is the assumption that the natural processes operating in the past are the same as those that can be (1797-1875) observed operating in the present.

Georges Cuvier –species extinction (1769-1832)

More people that contrubutored to Darwin’s ideas.

Thomas Malthus- struggle for existence 1766-1834

Jean Baptisite de Lamarck- evolution by acquired characteristics 1744-1829

Alfred Russell WallaceThought of natural selection at the same time as

Darwin (1959)Wrote to Darwin, collaborated with Darwin on

solidifying the theory of evolution through natural selection.

Darwin had been working on bookPublished a “letter” jointlyWallace didn’t put in the years of data that

Darwin did.Darwin published The Origin of Species without

Wallace

Darwin was MiscreditedDied famous for evolution (which

was not his idea)Natural selection was his big idea--

not widely accepted, even among his supporters

Darwin remained convincedOnly 40-50 years later did scientists

appreciate his foresight.

Charles Darwin’s IdeasNaturalist on the HMS Beagle, Five

year journeyVisits the Galapagos IslandsHe studied many organisms that

were unique to the islands, but similar to elsewhere.

After 22 years he proposed the process of natural selection.

The Voyage of the Beagle

Darwin’s Finches

Galapagos Islands500-600 miles west off the coast of EcuadorLocated directly on the equatorCold ocean coming from the south and warm

ocean current coming from the north meet at the islands

Galapagos Islands• Islands are of

volcanic origin (much like the Hawaiian islands)

The oldest islands are thought to be 5-10 million years old. (much younger than South America)

Started as a “blank slate.”

Not paid for 5 years on Beagle. Actually, he had to pay! Was the “Naturalist”Was lucky to get on

Replaced someone who was shot in a duelhis father opposed him going

Mainly asked because of his class, to keep Captain Fitzroy company

It was the making of him

Joining the Beagle Voyage

Portrayed as a “Eureka” experience. Did not recognize significance until back in England, 1837.Worked out theory much later.First inkling of natural selection in 1838.

Tortoises & finches were key evidence

Galapagos, 1835

How did living things get to the islands?Remember they have to survive a 500 mile journey.

Rafting on debris or chunks of land.

Birds may fly or be blown out in a storm.

How would you survive in this environment?

Galapagos Islands

Marine Iguana• Have been thought to evolve from an

ancestor similar to what we know as a green iguana.

Marine Iguana Live by

swimming in the ocean and scrapping algae off rocks.

Only known iguana that swims.

Marine Iguana CharacteristicsFlat Nose – Why?To scrape algae off

rocks.

Marine Iguana CharacteristicsLong, flat tailAllows it to swim in

the oceanBig clawsAllows it to hold

onto rocks while feeding

Marine Iguana CharacteristicsWhite stuff on back –

What is it?Salt – Salt glands in

nose– eats salty foods and the glands allow it to sneeze the salt out

Black Color – Why?Allows it to warm up

after being in the cold ocean

Land Iguana• Have been thought to evolve from an

ancestor similar to what we know as a green iguana.

Land Iguana

Lives on the landIs an Herbivore, eating mostly the fruit and

pads of cactus

Land Iguana CharacteristicsBigger jaw/mouth

than the marine iguana – WHY?

Allows it to eat cactus

Lighter coloring –WHY?

Doesn’t heat up as fast.

Land Iguana CharacteristicsNeck flap (gular sack)

WHY?Acts as a cooling system,

allows heat to escape body

Short, stubby legs – Why?

Allows it to support it’s big weight

Bigger Body – WHY?Resists heating up in the

desert sun

SOMETHING TO THINK ABOUTWhy did the land iguana and marine iguana evolve so differently from one another?

Galapagos Tortoise

Galapagos TortoiseHave been thought to evolve from an

ancestor similar to our desert tortoise.

Galapagos Tortoise CharacteristicsLive around 150

yearsThere were around

250,000 around Darwin’s time.

Numbers have declined to 15,000 or less.

Key source of meat for pirates and explorers.

ContinuedHigh shell at neck – Why?Allows it to stretch to reach

food.Bigger body size – Why?Takes longer for an organism to

warm up in the hot desert sun.

Plants Evolve Too!

Swallow-tail GullFlies and feeds at night

Swallow-tail Gull CharacteristicsDark, Black coloring –

WHY?Allows it to fly at night

without being spotted by Frigate Bird

Red Ring around the eye – WHY?

Red eye ring is thought to attract more light to allow bird to see at night.

White spot on beak – WHY?

When feeding at night chicks can peck on the white spot to tell the mother where they are.

MockingbirdMockingbirds will

peck at the iguanas, tortoises, and other birds and drink their blood during hard times when water is scarce.

This is an example of a behavioral adaptation.

How have humans impacted the islands?Introduced Exotic Species

Pigs, dogs, catsInvasive species of plants

TourismMany people travel to the islandsWhile the islands are mostly national parks and quite

regulated, they have to deal with the conservation problems that humans yachts and trash bring to the islands.

Increase in PopulationPeople are moving to the islands looking for workThe increase in tourism brings the need for more workersThis puts more pressure on the natural resources of the

islands

Natural SelectionA mechanism for change in populations.

Natural Selection1. In nature,

organisms produce more offspring than can survive.

2. In any population, individuals have variations.

3. Individuals with certain useful variations survive in their environment, passing those variations to the next generation. “Survival of the Fittest”

4. Over time, offspring with certain variations make up most of the population and may look entirely different from their ancestors.

Peppered MothsOnline Example