Evidence for Evidence for EvolutionEvolution

EQ: How do the various forms EQ: How do the various forms of evidence support the of evidence support the

theory of evolution?theory of evolution?

Evidence for EvolutionEvidence for Evolution

►BiogeographyBiogeography The distribution of plants and animals The distribution of plants and animals

world wide follows a set patternworld wide follows a set pattern Isolated islands have similar plants and Isolated islands have similar plants and

animals as the mainlandanimals as the mainland Fossils of the same animal are found on Fossils of the same animal are found on

different continentsdifferent continents

BiogeographyBiogeography

Evidence for EvolutionEvidence for Evolution

► Comparative AnatomyComparative Anatomy Homologous structures exist in different speciesHomologous structures exist in different species

►These are structures that are similar in form but These are structures that are similar in form but different in functiondifferent in function

Embryological similarities existEmbryological similarities exist►The developmental stages of closely related organisms The developmental stages of closely related organisms

are similarare similar

Molecular BiologyMolecular Biology►Compare the DNA of two different speciesCompare the DNA of two different species►The more similarities that exist the more related the The more similarities that exist the more related the

organism are to each otherorganism are to each other

Homologous StructuresHomologous Structures

includes

Evidence of Evolution

Physical remains of organisms

Common ancestral species

Similar genes Similar genes

which is composed of which indicates which implies which implies

The fossil record

Geographic distribution of living species

Homologous body

structures

Similaritiesin early

development

Natural Selection Theory Natural Selection Theory AssumptionsAssumptions

►More offspring are born than can More offspring are born than can survivesurvive

►There is phenotypic variation within a There is phenotypic variation within a populationpopulation Variations are caused by changes or Variations are caused by changes or

mutations in the DNAmutations in the DNA Mutations occur by random chanceMutations occur by random chance

►All organisms struggle to surviveAll organisms struggle to survive►Nature selects those variations that are Nature selects those variations that are

best fit for the environmentbest fit for the environment

Evidence for EvolutionEvidence for Evolution

►Fossils are the remain of ancient Fossils are the remain of ancient organisms preserved in the different organisms preserved in the different layers of rockslayers of rocks

►The law of superposition states that The law of superposition states that the fossils in the top layers of the the fossils in the top layers of the earth are younger than the fossils earth are younger than the fossils found in the lower layers of the earthfound in the lower layers of the earth

►Often shows how species changed Often shows how species changed over timeover time

http://www.youtube.com/watch?v=NyqBYO894eM

Age of ThingsAge of Things

► In 1778 a scientist named Hutton brought In 1778 a scientist named Hutton brought up the idea that the earth was very oldup the idea that the earth was very old The rocks, mountains and valleys were all The rocks, mountains and valleys were all

shaped over time by erosionshaped over time by erosion Finally have agreed upon the age of ~ 4.6 Finally have agreed upon the age of ~ 4.6

billions yearsbillions years►Geologic Time ScaleGeologic Time Scale

The rocks on the bottom are older than the rocks The rocks on the bottom are older than the rocks on top of any land featureon top of any land feature

Allowed scientists to place the age of fossils Allowed scientists to place the age of fossils found in the rocks through relative datingfound in the rocks through relative dating

Called the law of superpositionCalled the law of superposition

Radioactive DatingRadioactive Dating

► Used to date rocks and fossils with more Used to date rocks and fossils with more accuracy than relative datingaccuracy than relative dating

► Rocks and bones contain radioactive Rocks and bones contain radioactive elementselements A radioactive element is one that is unstable in A radioactive element is one that is unstable in

its current form and eventually breaks down into its current form and eventually breaks down into a more stable form releasing heata more stable form releasing heat

The amount of time for half of the element to The amount of time for half of the element to break down is its half – lifebreak down is its half – life►The amount of time it takes for half of the elements to The amount of time it takes for half of the elements to

go from unstable to stablego from unstable to stable

Radioactive Radioactive DatingDating

► Different elements have Different elements have different half lives different half lives allowing scientists to allowing scientists to fairly accurately pinpoint fairly accurately pinpoint when the organism diedwhen the organism died

► This is done by This is done by comparing how much of comparing how much of an element is still an element is still unstable with how much unstable with how much is stableis stable

► Old form used COld form used C14 14 but it but it has a large margin of has a large margin of errorerror

► New form uses KNew form uses K4040

Geologic Time PeriodsGeologic Time Periods

► PrecambrianPrecambrian Life on earth begins – we Life on earth begins – we

thinkthink Is it possible that life Is it possible that life

began before this?began before this?► Earliest fossils of life are Earliest fossils of life are

dated to 3.5 billion years dated to 3.5 billion years agoago

► Some evidence suggests Some evidence suggests it started around 3.8 it started around 3.8 billion years agobillion years ago

Early animals were single Early animals were single and multicellularand multicellular

Some show evidence of Some show evidence of cellular organization like cellular organization like modern jellyfishmodern jellyfish

PaleozoicPaleozoic► Time of major evolutionTime of major evolution► Organisms with shells and Organisms with shells and

skeletons appearskeletons appear► Size of individuals increasedSize of individuals increased

First invertebrates like the First invertebrates like the trilobitestrilobites

First jawless fishFirst jawless fish First fish and forestsFirst fish and forests

► The earth became The earth became inhabitable by organisms inhabitable by organisms much like the ones we see much like the ones we see todaytoday

► Ends in mass extinctionEnds in mass extinction 90% of all marine species90% of all marine species 66% of all reptile and 66% of all reptile and

amphibiansamphibians 30% of all insects30% of all insects

MesozoicMesozoic► Age of the dinosaursAge of the dinosaurs

The dinosaurs came The dinosaurs came and went in the and went in the mesozoicmesozoic

Were only on the Were only on the planet for 70 million planet for 70 million yrsyrs

► First mammals and First mammals and flowering plantsflowering plants

► Rocky mountains Rocky mountains appearedappeared

► Ended with a major Ended with a major extinctionextinction Most likely caused Most likely caused

by a meteor by a meteor crashing in the Gulf crashing in the Gulf of Mexicoof Mexico

Changed the climate Changed the climate

CenozoicCenozoic

► Age of the mammalAge of the mammal Grasses become Grasses become

abundantabundant First early horses appearFirst early horses appear Whales and other large Whales and other large

mammals appearmammals appear

► Humans evolved during Humans evolved during this timethis time

► Variable climatesVariable climates► Sea life very similar to Sea life very similar to

todaytoday

Age of CivilizationAge of Civilization

► Early man appears Early man appears 2.5 million years 2.5 million years ago ago

►Many different Many different species of man exist species of man exist before our present before our present state is reachedstate is reached

► Possible that more Possible that more than one species of than one species of man was present at man was present at any given timeany given time

AthropoceneAthropocene

► Age of ManAge of Man►New geologic EpochNew geologic Epoch

Defined by man’s influence on the environmentDefined by man’s influence on the environment► Started approximately 8000 years agoStarted approximately 8000 years ago

This is the time in which man began using This is the time in which man began using agriculture to create foodagriculture to create food

38% of the land is now used for farming38% of the land is now used for farming► Actual start is being debatedActual start is being debated

First purposed in 1870First purposed in 1870 First scientific papers published using it as an First scientific papers published using it as an

official time period were published in the early official time period were published in the early part of this centurypart of this century