Transcript rEvolutionary Thinkers

rEvolutionary
Thinkers
DOCTRINE
TINTORETTO
The Creation of the Animals 1550
Evolution: History
 Western View Around 1759



No change in organisms
Inhabitants were divinely created
Species did not change over time
But The Fossil record…
OBSERVATION
Triassic
Permian
225
Seed Plants
Land Plants
Birds
Mammals
Reptiles
Insects
Amphibians
Teleost Fish
Jawless Fish
Chordates
Arthropods
Flowering Plants
180
Dinosaurs
Jurassic
135
Molluscs
Cretaceous
63
Multicellular Animals
Tertiary
Green Algae
1.5
Photosynthetic Bacteria
Quaternary
Anaerobic Bacteria
MYA
280
Carboniferous
350
Devonian
Silurian
Ordovician
Cambrian
Ediacaran
400
430
500
570
700
Precambrian,
Proterozoic,
&
Archarozoic 4500
Life’s Natural History is a record of Successions & Extinctions
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
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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 Islands
Most 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
Succession of Types
Armadillos are native to the
Americas, with most species
found in South America.
Why should extinct
armadillo-like species
& living armadillos be
found on the same
continent?
Glyptodont fossils are also
unique to South America.
Unique Species
Darwin found… birds
Collected many
different birds on the
Galapagos Islands.
Finch?
Thought he found
very different kinds…
Woodpecker?
Sparrow?
Warbler?
But Darwin found… a lot of finches
Darwin was amazed to
find out:
All 14 species of birds
were finches…
But there is only one
species of finch on the
mainland!
Large
Ground
Finch?
Finch
Small
Ground
Sparrow?
Finch
How did
one species
of finches become
so many different
species now?
Warbler
Finch
Woodpecker?
Veg.Warbler?
Tree Finch
Correlation of species to food source
Seed
eaters
Flower
eaters
Insect
eaters
Rapid speciation:
new species filling new niches,
because they inherited
successful adaptations.
Adaptive radiation
Darwin’s Finches
 Differences in beaks
Associated with eating different foods
 Survival & reproduction of beneficial
adaptations to foods available on islands

Warbler finch
Cactus finch
Woodpecker finch
Sharp-beaked finch
Small insectivorous
tree finch
Large
insectivorous
tree finch
Small ground
finch
Cactus
eater
Medium
ground finch
Insect eaters
Seed eaters
Vegetarian
tree finch
Bud eater
Large
ground finch
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 species
into 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….
Then, in 1858, Darwin received a letter
that changed everything…
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.
The time was ripe for the idea!
To Lyell—
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.
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
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 more offspring than the environment can support
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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
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Variation is heritable