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AP Biology

2006-2007AP Biology

Evolutionby

Natural Selection

2006-2007AP Biology

"Nothing in biology makes sense except in the light of evolution."

-- Theodosius DobzhanskyMarch 1973

Geneticist, Columbia University

(1900-1975)

AP BiologyTINTORETTO The Creation of the Animals 1550TINTORETTO The Creation of the Animals 1550

AP Biology

But the Fossil record…

AP BiologyLife’s Natural History is a record of Successions & Extinctions

Precambrian,

Proterozoic,

&

Archarozoic

Ediacaran

Cambrian

Ordovician

Silurian

Devonian

Carboniferous

Permian

Triassic

Jurassic

Cretaceous

Tertiary

Quaternary

An

ae

rob

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Inse

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Re

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Din

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Ma

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Bir

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La

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Se

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Pla

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Art

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Ch

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ish

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Am

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1.5

4500

700

63

135

180

225

280

350

400

430

500

570

Flo

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rin

g

mya

AP Biology

Life has changed & changed the Earth

Living creatures havechanged Earth’s environment, making other life possible

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AP Biology

AP Biology

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 same

continent?

AP Biology

Mylodon Mylodon (left)(left) Giant Giant ground sloth ground sloth (extinct)(extinct)

Modern sloth Modern sloth (right)(right)

This wonderful relationship in the same continent between

the dead and the living will…throw more light on the appearance of organic beings on our earth,

and their disappearance from it, than any other class of facts.

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LaMarck

� Organisms adapted to their environments

� through acquired traits

�� change in their life timechange in their life time�� Use & DisuseUse & Disuse

organisms lost parts because they did not use them organisms lost parts because they did not use them —— like the missing eyes & digestive system of the like the missing eyes & digestive system of the tapewormtapeworm

�� Perfection with Use & NeedPerfection with Use & Needthe constant use of an organ leads that organ to the constant use of an organ leads that organ to increase in size increase in size —— like the muscles of a blacksmith like the muscles of a blacksmith or the large ears of a nightor the large ears of a night--flying batflying bat

� transmit acquired characteristics to next generation

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In historical context� Darwin did not originate the idea of evolution� Geologic theories of Earth’s age & history cleared the

path for evolutionary biologists

…immeasurable time…

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Charles Darwin

� 1809-1882

� British naturalist

� Proposed the idea of evolution by natural selection

� Collected clear evidence to support his ideas

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Voyage of the HMS Beagle

� Travels around the world

� 1831-1836

� makes many observations of natural world

� main mission of the Beagle was to chart South American coastline

Robert FitzroyRobert Fitzroy

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AP Biology

Voyage of the HMS Beagle

� Stopped in Galapagos Islands

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GalapagosOf relatively recent volcanic origin most of animal species on the Galápagos live nowhere else in world, but they resemble species living on South American mainland.

500 miles west of mainland

AP Biology

Unique species

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