Charles Darwin and evolution

How do you think these different fish

came to be?

How about these different typesof vegetables?

Answer: the fish and the vegetableshave both descended from a commonancestor. The principals of evolution and natural selection apply to all life.

It all started with Mr. Darwin!

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www.darwinday.org/englishL/life/beagle.html

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A perfect natural ‘experiment’ in evolution

At first there is one bird species. Over time these birds spread out to different islands. There are different foods on the different islands. To survive the birds MUST be able to eat the food on their island. Birds which can eat survive and have babies, birds that cannot eat DIE—this is natural selection. Much time passes. Now a new species which can eat the local food thrives on each island. After being separated for a very long time these birds can no longer mate with birds on the other islands. This creation of a new species is called speciation .

What Darwin Figured OutOn the Galapagos Islands

GALAPAGOS BIRDS’ ANCESTRY

Life Sciences-HHMI Outreach. Copyright 2006 President and Fellows of Harvard College.

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Main Points of Darwin’s Theory

• There is variation within populations.

• Some variations are more favorable than others.

• The survivors reproduce and pass on favorable traits.

• Over huge spans of time, the small changes add up and the population changes.

Artificial selection is similar– Farmers wanted cows

that make more milk.

– They chose animals with desired characteristics and bred them.

–Result: more offspring with the desired characteristics.

Now we know Darwin’s theory applies to all life…….

WHAT IS NATURAL SELECTION?

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SPECIATION: how do new species form if not on islands?

Life Sciences-HHMI Outreach. Copyright 2006 President and Fellows of Harvard College.

http://evolution.berkeley.edu/evolibrary/home.php

EVIDENCE: ANATOMY

ANATOMY

– HOMOLOGOUS STRUCTURES

Life Sciences-HHMI Outreach. Copyright 2006 President and Fellows of Harvard College.

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Homologous Structures (bones)

• Same BONE structure, different function

CONVERGENT EVOLUTION – different paths similar end: bird and bat wings

Life Sciences-HHMI Outreach. Copyright 2006 President and Fellows of Harvard College.

http://evolution.berkeley.edu/evolibrary/home.php

Vestigial means ‘leftover’: these are structures still in our bodies left over from previous stages of evlution. We don’t need them any more. Like gills from a fish.

Wow we lookSimilar!!!

Now you canTell who is who!

Really differentNow!

Adaptations

Any variation that aids an organism’s chances of survival in its environment

EVIDENCE: ADPATATIONS

SURVIVAL ADAPTATIONS– MIMICRY– CAMOUFLAGE

Life Sciences-HHMI Outreach. Copyright 2006 President and Fellows of Harvard College.

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EVIDENCE: Fossils• Remains of

organisms or their imprints that have been preserved

• The fossil record shows change of life

forms over long periods of time.

Evidence for Evolution

• The Fossil Record-Layer show change

• Geographic Distribution of Living Things

• Homologous Body Structures

• Similarities in Early Development

Evidence of Evolution• The Fossil Record• Geographic

Distribution of Living Things-similar environments have similar types of organisms

• Homologous Body Structures

• Similarities in Early Development

1. Location on Earth

Summary of Darwin’s Theory

• Because more organisms are produce than can survive, each species must struggle for resources

• Each organism is unique, each has advantages and disadvantages in the struggle for existence

Summary (cont.)

• Individuals best suited for the environment survive and reproduce most successful

• Species change over time

Summary of Darwin’s Theory

• Individuals in nature differ from one another

• Organisms in nature produce more offspring than can survive, and many of those who do not survive do not reproduce.

Evidence for Evolution• Fossils (rock records)

• Embryo Development (we can see this)

• Adaptations through natural selection

• Homologous structures (bones)

• DNA relationships (genes we share)

EVOLUTION HAPPENING TODAY

WHAT DO YOU HEAR ABOUT IN THE NEWS ABOUT SOME BACTERIA?

– TUBURCULOSIS IN DRUG ADDICTS

– STAPH IN HOSPITALS

– THE GUY EVERYONE WAS CHASING ACROSS THE GLOBE

WHY HAS IT BEEN SO HARD TO FIND A CURE FOR HIV?

WHY DO PEOPLE WITH HIV HAVE TO TAKE THE DRUGS FOR IT EVERY COUPLE OF HOURS?

PERCENTDRUG RESISTANT