Where did Where did all this all this

diversity diversity come come from?!from?!

► WhyWhy do these organisms look so do these organisms look so similar?similar? What has shaped their appearance over What has shaped their appearance over

time?time?

►WhyWhy are all these animals white? are all these animals white?

► Why Why are Lemurs found are Lemurs found onlyonly on Madagascar? on Madagascar?

► How does something like THIS come How does something like THIS come about?!!about?!!

The Facts….The Facts….► 99% of everything that has ever lived no longer 99% of everything that has ever lived no longer

exists on the Earth – it is exists on the Earth – it is extinctextinct► Some modern organisms look very similar to other Some modern organisms look very similar to other

unrelatedunrelated organisms (ex. Ant-eaters & Echidnas) organisms (ex. Ant-eaters & Echidnas)► Some modern organisms look very similar to ancient Some modern organisms look very similar to ancient

organisms that are now extinct (ex. fossils)organisms that are now extinct (ex. fossils)► For centuries, people looked at these fossils and For centuries, people looked at these fossils and

tried to EXPLAIN what they are, and what they meantried to EXPLAIN what they are, and what they mean What hypotheses could you propose for the diversity of What hypotheses could you propose for the diversity of

life?life? What evidence could you gather?What evidence could you gather? What do you ALREADY KNOW about inheritance?What do you ALREADY KNOW about inheritance?

““EVOLUTION” – what’s all the EVOLUTION” – what’s all the fuss about?!fuss about?!

► Theory = Theory = “a scientific explanation of natural “a scientific explanation of natural phenomena, based on empirical evidence”phenomena, based on empirical evidence” A theory brings together all the research into a single A theory brings together all the research into a single

cohesive, testable explanationcohesive, testable explanation

► Evolution =Evolution = “ “change over time”change over time” A A scientificscientific explanation for the origin, diversity and explanation for the origin, diversity and

continued change observed within living thingscontinued change observed within living things Defined more specifically in Biology as “descent with Defined more specifically in Biology as “descent with

modification” (ie. The things alive today are modified modification” (ie. The things alive today are modified versions of their ancestors…just like you and me!)versions of their ancestors…just like you and me!)

Physical traitsPhysical traits are passed-on to offspringare passed-on to offspring Some traits are beneficial, others aren’tSome traits are beneficial, others aren’t The beneficial traits remain in the population, and The beneficial traits remain in the population, and

become more common over time – THIS IS become more common over time – THIS IS “EVOLUTION”…“EVOLUTION”…

Let’s back up: “In The Let’s back up: “In The Beginning…”Beginning…”

► ALEXANDER OPARIN - FORMATION OF MACROMOLECULES ALEXANDER OPARIN - FORMATION OF MACROMOLECULES WITHOUT OXYGENWITHOUT OXYGEN

► STANLEY MILLER AND HAROLD UREY EXPERIMENTSTANLEY MILLER AND HAROLD UREY EXPERIMENT ““Created” amino acids from simulated early Earth Created” amino acids from simulated early Earth

conditions…conditions…

http://en.wikipedia.org/wiki/Image:Miller-Urey_experiment_en.png creative commons copyright

► FIRST SIMPLE BACTERIA APPEARED AROUND 3.5 FIRST SIMPLE BACTERIA APPEARED AROUND 3.5 BILLION YEARS AGOBILLION YEARS AGO

► SOME ARE CYANOBACTERIA - THESE ARE SOME ARE CYANOBACTERIA - THESE ARE PHOTOSYNTHETIC BACTERIA (PHOTOSYNTHETIC BACTERIA (Stromatolites…Stromatolites…)) WHAT GAS DID THESE BACTERIA PRODUCE?WHAT GAS DID THESE BACTERIA PRODUCE? ATMOS. WAS ALMOST 10% OATMOS. WAS ALMOST 10% O2 2 ABOUT 2.5 BILLION YEARS ABOUT 2.5 BILLION YEARS

AGOAGO WHAT TYPE OF CELLS ARE BACTERIA?WHAT TYPE OF CELLS ARE BACTERIA? WHAT TYPE OF CELLS ARE ALL OTHER ORGANISMS?WHAT TYPE OF CELLS ARE ALL OTHER ORGANISMS?

► WHERE DID EUKARYOTIC CELLS COME FROM?WHERE DID EUKARYOTIC CELLS COME FROM?► ENDOSYMBIOSIS…ENDOSYMBIOSIS…

THE FIRST CELLS!!!

Dr Gordon Beakes © University of Newcastle upon Tynelicensed for use through the Centre for Bioscience ImageBank,http://www.bioscience.heacademy.ac.uk/imagebank/"

evolution.berkeley.edu/evolibrary/article/0_0_0/endosymbiosis_03

ENDOSYMBIONT THEORYENDOSYMBIONT THEORY THE BEGINNING OF THE EUKARYOTIC THE BEGINNING OF THE EUKARYOTIC

CELLSCELLS► EVIDENCE FOR ENDOSYMBIOSISEVIDENCE FOR ENDOSYMBIOSIS

DNA & structural similaritiesDNA & structural similarities

Summary of Darwin’s Summary of Darwin’s Theory of EvolutionTheory of Evolution

1. Individual organisms in nature 1. Individual organisms in nature differ from one anotherdiffer from one another

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2. Organisms produce more offspring 2. Organisms produce more offspring than can survive.than can survive.

Frog eggs

Turtle eggs

Insect eggs

Lobster eggs

3. Members of each species 3. Members of each species must compete for limited must compete for limited resources.resources.

4. Each organism has different 4. Each organism has different advantages and advantages and disadvantages for the struggle disadvantages for the struggle of existence.of existence.

5. Individuals best-suited to 5. Individuals best-suited to their environment survive and their environment survive and reproduce. Those not suited reproduce. Those not suited will be less likely to breedwill be less likely to breed

► Survival of the fittest!Survival of the fittest!

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Nature (the environment) will Nature (the environment) will determine which organism is determine which organism is

the fittest to Survivethe fittest to Survive

6. Species change over time, by 6. Species change over time, by passing on their useful (and passing on their useful (and harmful) traits to their offspringharmful) traits to their offspring

7. All species 7. All species alive today have alive today have therefore therefore descended with descended with modifications modifications from ancient from ancient ancestorsancestors

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FossilFossilrecord record of the of the camelcamel

8. Ultimately, 8. Ultimately, ALL ALL organisms on organisms on Earth are united into a single Earth are united into a single tree of life…tree of life…

Darwin’s original sketchbook drawing

Darwin’s Theory is supported by….Darwin’s Theory is supported by….

ARTIFICIAL SELECTIONARTIFICIAL SELECTION

► Nature provides Nature provides variation but variation but humans decide humans decide what traits are what traits are selected andselected and passed passed on.on.

► Hybridization brings Hybridization brings about new about new variationsvariations

Descent with ModificationDescent with ModificationDarwin proposed that after long periods of time, offspring of ancient organisms spread out through the environment, and natural selection then results in organisms with traits that are very different from their ancestor

•Different structures

•Different niches

•Different habitats

We call this Adaptive Radiation

Evidence of EvolutionEvidence of Evolution

► FossilFossil RecordsRecords--fossils being fossils being discovered were discovered were evidence that evidence that the world was the world was much older that much older that once thought.once thought.

99% of species that once lived are now extinct!!!!!!Did

you

know????Some fossils were very

similar to modern day creatures

Fossils Fossils show history of life on Earthshow history of life on Earth

Relative Relative DatingDating --The The layering of layering of rock can rock can show which show which fossils are fossils are older.older.

Fossils show history of life on EarthFossils show history of life on Earth

Radioactive DatingRadioactive Dating --using the half-life of radioactive using the half-life of radioactive elements scientists can tell approx. how old a fossil is…elements scientists can tell approx. how old a fossil is…

What Does The Fossil Record What Does The Fossil Record Tell Us About Evolution?Tell Us About Evolution?

► Sedimentary rocks can be dated by studying the Sedimentary rocks can be dated by studying the decay of radioactive isotopesdecay of radioactive isotopes they contain. they contain.

► In some cases, successive layers of rocks of In some cases, successive layers of rocks of different ages are so well-preserved that different ages are so well-preserved that families of similar fossils can be families of similar fossils can be traced through traced through the layersthe layers, over several million years of history, over several million years of history

► This apparent transition suggests a pattern of This apparent transition suggests a pattern of development, and allows scientists to development, and allows scientists to infer infer changes changes from one form to another and construct from one form to another and construct a diagram called a a diagram called a Phylogenetic Tree…Phylogenetic Tree…

Trilobite EvolutionTrilobite Evolution

Phylogenetic trees show the evolutionary ancestry of organisms, based on their inferred relationships to ancestral species

The History Of The History Of LifeLife

► The fossil record has The fossil record has allowed scientists to allowed scientists to locate the “first locate the “first appearance” of different appearance” of different organisms within rocks organisms within rocks of a specific ageof a specific age

► The pattern of change & The pattern of change & progression suggests progression suggests that recent organisms that recent organisms might be might be modified formsmodified forms of ancient organisms of ancient organisms that previously existedthat previously existed

The Geological TimescaleThe Geological Timescale

Based ONLY on the fossil Based ONLY on the fossil evidence, it appears that evidence, it appears that the nature and diversity of the nature and diversity of life on our planet has life on our planet has changed dramatically changed dramatically throughout Earth’s historythroughout Earth’s history

• But HOW have these But HOW have these changes occurred?changes occurred?