Theory of E v o l ut i o n. What is Evolution? Change over time The process by which modern organisms have descended from ancient organisms.

Theory ofTheory of

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What is Evolution?What is Evolution?

• Change over time

• The process by which modern organisms have descended from ancient organisms

2 Competing Theories2 Competing Theories::

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Darwin and Lamarck agreed on Darwin and Lamarck agreed on a few things…a few things…

• Life is still changing

• Living things become better suited to their environment

• All organisms are related

• Simple Complex

LamarckLamarck• Organisms can change the shape or size of

organs depending on how they use them– Most usedMost used body structures develop, body structures develop, unusedunused

structures waste awaystructures waste away

• Acquired characteristicsAcquired characteristics could be inherited.– If an animal altered its body during its lifetime, that

change will pass to offspring

• Organisms have a tendency toward perfection

DarwinDarwin

Charles DarwinCharles Darwin“The Father of Evolution”“The Father of Evolution”

• 1831- sailed on the HMS Beagle to 1831- sailed on the HMS Beagle to the the Galapagos IslandsGalapagos Islands..

• Studied many species of finches.Studied many species of finches.

• Published book in 1845:Published book in 1845:

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

Natural SelectionNatural Selection

• Only certain individuals of a population reproduce

• The traits being selected contribute to fitness in the environment

Survival of the FittestSurvival of the Fittest

• What is meant by fittest?

• How well you “fit” in your environment

Four main points…Four main points…

• 1. More organisms are produced than can 1. More organisms are produced than can survive…leads to survive…leads to COMPETITION OVER COMPETITION OVER RESOURCESRESOURCES

• Ex’s of resources…Ex’s of resources…– WaterWater– FoodFood– HabitatHabitat– Mates Mates

2. Individuals within a population 2. Individuals within a population vary, and some of these traits are vary, and some of these traits are

heritable.heritable.

3. Some variations are 3. Some variations are FAVORABLE FAVORABLE (increase chances for (increase chances for

survival/ reproduction)survival/ reproduction)• Male vs. Female Male vs. Female

CardinalsCardinals

• Male color attracts Male color attracts female= reproductive female= reproductive advantageadvantage

4.4. Better adapted individuals Better adapted individuals survive and reproducesurvive and reproduce

• These are the individuals that will pass on their These are the individuals that will pass on their genes to the next generation.genes to the next generation.

• This can change the GENE POOL:This can change the GENE POOL:– Includes all the genes of every reproductive member Includes all the genes of every reproductive member

of a populationof a population

• Favorable heritable traits become more Favorable heritable traits become more common in future generations and common in future generations and unfavorable heritable traits become less unfavorable heritable traits become less common.common.

What The theory of evolution IS What The theory of evolution IS NOT!!!NOT!!!

• It does NOT occur in INDIVIDUALS…only It does NOT occur in INDIVIDUALS…only populations!populations!

• It does NOT happen quickly…the Earth It does NOT happen quickly…the Earth has a Looooooong history!has a Looooooong history!

• It does NOT explain how life came to be It does NOT explain how life came to be on Earth, just how it evolved after it was on Earth, just how it evolved after it was here.here.

• It does NOT have any driving force except It does NOT have any driving force except the competition for limited resources.the competition for limited resources.

LamarckLamarck- - why was he wrong??why was he wrong??

– Lamarck did not know how traits were inherited

– He did not know that an organism’s behavior has no effect on the traits it passes down

– Acquired characteristics are not passed on to offspring

– Organisms do not get what they "need" through "inner wants" or through "use and disuse” Individual intentions do not play a role.

– Instead, the organisms well suited survive and reproduce while those ill suited die