rEvolutionary Thinkers

TINTORETTO The Creation of the Animals 1550TINTORETTO The Creation of the Animals 1550DOCTRINEDOCTRINE

Evolution: History Western View Around 1759

No change in organisms Inhabitants were divinely created Species did not change over time

But The Fossil record…

OBSERVATIONOBSERVATION

Life’s Natural History is a record of Successions & Extinctions

Quaternary

Tertiary

Cretaceous

Jurassic

Triassic

Permian

Carboniferous

Devonian

Silurian

Ordovician

Cambrian

Ediacaran

Precambrian,

Proterozoic,

&

Archarozoic

An

aero

bic

Bac

teri

a

Inse

cts

Rep

tile

s

Din

os

aurs

Mam

ma

ls

Bir

ds

Lan

d P

lan

ts

See

d P

lan

ts

Pla

nts

Art

hro

po

ds

Ch

ord

ates

Jaw

les

s F

ish

Tel

eo

st F

ish

Am

ph

ibia

ns

Ph

oto

syn

thet

ic B

acte

ria

Gre

en A

lga

e

Mu

ltic

ellu

lar

An

ima

ls

Mo

llu

scs

1.5

4500

700

63

135

180

225

280

350

400

430

500

570

Flo

wer

ing

MYA

Cuvier

Cuvier

First to to document extinction Violent and sudden catastrophes Explains why the fossil record

shows abrupt changes in species living in the area

Plants and animals were created for their role in the environment, and were unchanged

LaMarck

LaMarck Believed organisms evolve gradually

and progressively into more complex forms through striving for perfection Believed the ultimate goal of perfection

was the human Traits were acquired through use and

disuse Traits were passed on to offspring

Lyell

Lyell Wrote a book called Principles of

Geology Darwin read the book while aboard the

HMS Beagle Showed evidence that the forces of

geological change that have been shaping Earth for millennia is observable today

Suggested the Earth had been around for a long time

Malthus

Malthus Population growth theory

Population was growing exponentially (i.e. 2, 4, 8, 16, 32, 64, 128, etc.)

Whereas the food supply grows at an steady rate (i.e. 1, 2, 3, 4, 5, 6, 7, 8, etc.)

This difference in growth influenced both Darwin and Wallace

Charles Darwin

Charles Darwin 1809-1882 British naturalist Proposed the idea of evolution by

natural selection Collected clear evidence to support his

ideas

Voyage of the HMS Beagle

Voyage of the HMS Beagle Darwin was invited to travel around the

world on the HMS Beagle 1831-1836 (22 years old!) makes many observations of nature

HMS Beagle stopped at the Galapagos Islands

Galapagos IslandsMost of the animal species on the Galápagos live nowhere else in world, but they resemble species living on South American mainland.

500 miles west of mainland

Armadillos are native to the Armadillos are native to the Americas, with most species Americas, with most species found in South America.found in South America.

Glyptodont fossils are also Glyptodont fossils are also unique to South America.unique to South America.

Succession of Types

Why should extinct armadillo-like species& living armadillos be

found on the samecontinent?

Unique Species

Darwin found… birds

Finch? Sparrow?

Woodpecker? Warbler?

Collected many Collected many different birds on the different birds on the Galapagos Islands. Galapagos Islands.

Thought he found Thought he found very different kinds…very different kinds…

Darwin was amazed to find out: All 14 species of birds were finches…

Finch? Sparrow?

Woodpecker? Warbler?

But Darwin found… a lot of finches

Large Ground Finch

Small Ground Finch

Warbler Finch Veg. Tree Finch

But there is only one species of finch on the mainland!

How didone species

of finches becomeso many different

species now?

Correlation of species to food source

Adaptive radiation

SeedSeedeaterseaters

FlowerFlowereaterseaters

InsectInsecteaterseaters

Rapid speciation:new species filling new niches,

because they inheritedsuccessful adaptations.

Warbler finch

Woodpecker finch

Small insectivoroustree finch

Largeinsectivorous

tree finch

Vegetariantree finch

Cactus finch

Sharp-beaked finch

Small groundfinch

Mediumground finch

Large ground finch

Insect eaters

Bud eater

Seed eaters

Cactuseater

Warbler

finch

Tree

finc

hes G

round finches

Darwin’s Finches Differences in beaks

Associated with eating different foods Survival & reproduction of beneficial

adaptations to foods available on islands

Darwin’s Finches Darwin’s Conclusions

Small populations landed on islands Variation enabled individuals differential success Over many generations, populations changed Accumulation of advantageous traits Emergence of different species

Many islands also show distinct local variations in tortoise morphology…

…perhaps these are the first steps in the

splitting of one speciesinto several?

A Reluctant Revolutionary Returned to England in 1836 with all of

the information he gathered Wrote a draft in 1844 Left instructions to publish upon death

as he was reluctant to publish with regards towards beliefs at the time

And then came the letter….

Alfred Russel Wallace a young naturalist working in the East Indies, had written a short paper with a new idea. He asked Darwin to evaluate his ideas and pass it along for publication.

Alfred Russel Wallace a young naturalist working in the East Indies, had written a short paper with a new idea. He asked Darwin to evaluate his ideas and pass it along for publication.

Then, in 1858, Darwin received a letter that changed everything…

The time was ripe for the idea!

Your words have come true

with a vengeance… I never saw a more striking

coincidence…so all my originality, whatever it may amount to,

will be smashed.

To Lyell—

Voyage: 1831-1836

November 24, 1859, Darwin published

“On the Origin of Species by Means of Natural Selection”

Essence of Darwin’s ideas Natural selection

variation exists in populations over-production of offspring

more offspring than the environment can support competition

for food, mates, nesting sites, escape predators differential survival

Those with better suited traits survive and produce more offspring

differential reproduction adaptations become more common in population

Variation is heritable