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Evolution Evolution IntroIntro

Diversity of LifeDiversity of Life

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““Nothing in Nothing in biology biology

makes sense makes sense EXCEPT in the EXCEPT in the

light of light of evolution.” evolution.” Theodosius Theodosius DobzhanskyDobzhansky

Evolution

Charles Darwin in later yearsCharles Darwin in later years

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The Struggle for The Struggle for ExistenceExistence

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DefinitioDefinitionn

• Evolution is the slow , gradual change in a population of organisms over time

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Voyage of the BeagleVoyage of the Beagle

During His Travels, Darwin During His Travels, Darwin Made Numerous Made Numerous Observations And Observations And Collected Evidence That Collected Evidence That Led Him To Propose A Led Him To Propose A Revolutionary HypothesisRevolutionary Hypothesis About The Way Life About The Way Life Changes Over TimeChanges Over Time

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Darwin’s ObservationsDarwin’s Observations Patterns of Patterns of

Diversity were Diversity were shownshown

Unique Unique Adaptations in Adaptations in organismsorganisms

Species Not Evenly Species Not Evenly DistributedDistributed

» Australia, Australia, Kangaroos, but Kangaroos, but No RabbitsNo Rabbits

» S. America, S. America, LlamasLlamas

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Darwin’s ObservationsDarwin’s Observations

Both Living Both Living Organisms & Organisms & Fossils collectedFossils collected

Fossils Fossils included:included:»TrilobitesTrilobites»Giant Ground Giant Ground Sloth of South Sloth of South AmericaAmerica

This species NO longer existed.This species NO longer existed. What had happened to them?What had happened to them?

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Evidence for Evolution – The Fossil RecordEvidence for Evolution – The Fossil Record

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Darwin’s ObservationsDarwin’s Observations

Left unchecked, the number of organisms of each species will increase exponentially, generation to generation

In nature, populations tend to remain stable in size

Environmental resources are limited

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Darwin’s ConclusionDarwin’s Conclusion• Production of more

individuals than can be supported by the environment leads to a struggle for existence among individuals

• Only a fraction of offspring survive each generation

• Survival of the Fittest

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Darwin’s ObservationsDarwin’s Observations• Individuals of a

population vary extensively in their characteristics with no two individuals being exactly alike.

• Much of this variation between individuals is heritable.

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Darwin’s ConclusionDarwin’s Conclusion

• Individuals who inherit characteristics most fit for their environment are likely to leave more offspring than less fit individuals

• Called Natural Selection

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•The The unequal ability of individuals unequal ability of individuals to survive and reproduceto survive and reproduce leads to leads to a gradual change in a populationa gradual change in a population, , with favorable characteristics with favorable characteristics accumulating over generations accumulating over generations (natural selection)(natural selection)•New species evolveNew species evolve

Darwin’Darwin’s s

Theory Theory of of

EvolutioEvolutionn

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The Struggle for The Struggle for ExistenceExistence

Each Species Struggles For:– FoodFood– Living SpaceLiving Space– MatesMates

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Population GrowthPopulation GrowthPlants & Animals Plants & Animals

Produce Far More Produce Far More Offspring Than Can Offspring Than Can Be SupportedBe Supported– Most DieMost Die– If They Didn’t – Earth If They Didn’t – Earth

Would Be Overrun Would Be Overrun

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Darwin’s Theory of Darwin’s Theory of EvolutionEvolution

Populations and genetics Populations and genetics Change Over TimeChange Over Time

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Common Descent with Common Descent with ModificationModification

Darwin proposed Darwin proposed that that organisms organisms descended from descended from common ancestorscommon ancestors

Idea that Idea that organisms organisms change change with timewith time, , diverging from a diverging from a common formcommon form

Caused Caused evolution evolution of new speciesof new species

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Natural Selection Driving forceDriving force for for

evolutionevolution During the struggle for During the struggle for

resources, resources, best best adapted survive & adapted survive & reproducereproduce

Idea that at least Idea that at least some some of the differencesof the differences between individuals, between individuals, which impact their which impact their survival and fertility, survival and fertility, are are heritableheritable

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Darwin’s Notebook ProjectDarwin’s Notebook Project We will be taking a “Magic School Bus Ride” We will be taking a “Magic School Bus Ride”

around the world looking at the vast variety of around the world looking at the vast variety of life on earth just like Darwin’s voyage via “Planet life on earth just like Darwin’s voyage via “Planet Earth” and “Life” videos while ISATS are going Earth” and “Life” videos while ISATS are going on.on.

What is required?What is required?-List 25-50 different organisms-List 25-50 different organisms-1-2 different adaptations the organism -1-2 different adaptations the organism possesses that help it survive it’s environ.possesses that help it survive it’s environ.-An explanation of how each adaptation helps it -An explanation of how each adaptation helps it survive it’s environment… 1-2 sentences.survive it’s environment… 1-2 sentences.

1pt for each adaptation listed, 2 pt for each correct 1pt for each adaptation listed, 2 pt for each correct explanation= 100 total pts.explanation= 100 total pts.

THERE ARE NO EXCUSES ACCEPTED FOR NON-THERE ARE NO EXCUSES ACCEPTED FOR NON-COMPLETION…even ISATS!!!!!!!!!!!!!!COMPLETION…even ISATS!!!!!!!!!!!!!!

20A reconstruction of the HMS Beagle sailing off Patagonia.A reconstruction of the HMS Beagle sailing off Patagonia.

Darwin’s Voyage of Darwin’s Voyage of DiscoveryDiscovery

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HMS Beagle’s VoyageHMS Beagle’s Voyage