Chapter 15Chapter 15

This PowerPoint combines Darwin This PowerPoint combines Darwin information from both textsinformation from both texts It provides It provides a lota lot of background information that of background information that

should better help you understand the development should better help you understand the development of Darwin’s theories as well as give you a more of Darwin’s theories as well as give you a more thorough foundation of the history of Earth.thorough foundation of the history of Earth.

These PowerPoints will be online…please pay These PowerPoints will be online…please pay close attention in class as we will move quickly close attention in class as we will move quickly through themthrough them

Plate Tectonics and Continental Plate Tectonics and Continental Drift TheoryDrift Theory

Complete the Chapter 15 WebQuest: Complete the Chapter 15 WebQuest: ContinentalDriftQuest (located on the ContinentalDriftQuest (located on the Biology:Biology: Exploring LifeExploring Life site site

Try to explain how Plate Tectonics and Try to explain how Plate Tectonics and Continental Drift influenced evolution and Continental Drift influenced evolution and biodiversitybiodiversity

You will need to read "You will need to read "On the Move...Continental Drift and Plate Tectonics." –this is linked on that site = VERY ." –this is linked on that site = VERY USEFUL!USEFUL!

The Fossil RecordThe Fossil Record

Fossils/Their DatingFossils/Their Dating Fossil Record/Geologic Fossil Record/Geologic

Time ScaleTime Scale Continental Continental

Drift/MacroevolutionDrift/Macroevolution Mass ExtinctionsMass Extinctions

FossilsFossils

Formed from remains of organisms buried by Formed from remains of organisms buried by sediments, dust, or volcanic ashsediments, dust, or volcanic ash Soft body parts – usually decay rapidlySoft body parts – usually decay rapidly Hard body parts (shells, bones, or teeth) – may become Hard body parts (shells, bones, or teeth) – may become

preserved; long-lastingpreserved; long-lasting Hard body parts are hardened moreHard body parts are hardened more

Minerals dissolve in groundwaterMinerals dissolve in groundwater Seep into tissues of dead organisms and replace its organic Seep into tissues of dead organisms and replace its organic

materialmaterial Plant/animal becomes petrifiedPlant/animal becomes petrified

Fossils (cont.)Fossils (cont.)

Some rare fossils contain Some rare fossils contain organic materialorganic material Found as thin filmsFound as thin films Pressed between layers of Pressed between layers of

sand stone or shalesand stone or shale Ex. Idaho – plant leaves Ex. Idaho – plant leaves

millions of years old that are millions of years old that are still green with chlorophyllstill green with chlorophyll

Other Fossils: footprints, Other Fossils: footprints, animal burrows, sediment animal burrows, sediment impressionsimpressions

Preserved specimensPreserved specimens

Sometimes an organism Sometimes an organism happens to die in a place happens to die in a place where bacteria and where bacteria and fungi cannot decompose fungi cannot decompose the corpsethe corpse IceIce Plant sapPlant sap

Fossil Record/Geologic Time ScaleFossil Record/Geologic Time Scale

Fossil record is a “rich storehouse of Fossil record is a “rich storehouse of information” about macroevolutioninformation” about macroevolution

Geologic Time ScaleGeologic Time Scale PrecambrianPrecambrian PaleozoicPaleozoic MesozoicMesozoic CenozoicCenozoic

Geologic Time ScaleGeologic Time Scale

Periods are divided into epochsPeriods are divided into epochs Boundaries between eras are marked by a Boundaries between eras are marked by a

major change in forms of life and possibly major change in forms of life and possibly mass extinctionsmass extinctions

Dating FossilsDating Fossils

Know age of fossils based on location in Know age of fossils based on location in sedimentsediment

Relative Ages = reflect the order in which Relative Ages = reflect the order in which groups of species existed compared to one groups of species existed compared to one anotheranother

Absolute Ages = Actual ages in yearsAbsolute Ages = Actual ages in years

Radiometric DatingRadiometric Dating

Measurement of certain radioactive isotopes in Measurement of certain radioactive isotopes in objectsobjects

Every isotope has a fixed rate of decayEvery isotope has a fixed rate of decay Number of years for 50% of original sample to Number of years for 50% of original sample to

decay = half-lifedecay = half-life Unaffected by temperature, pressure and other Unaffected by temperature, pressure and other

environmental conditionsenvironmental conditions Used to date rocksUsed to date rocks

Fossils can sometimes be dated as wellFossils can sometimes be dated as well

Figuring out age of FossilsFiguring out age of Fossils

Could contain isotopes of elements that Could contain isotopes of elements that accumulated in the organisms when they were accumulated in the organisms when they were alive alive

When organism dies, intake of isotopes stops, When organism dies, intake of isotopes stops, but radioactive decay continuesbut radioactive decay continues

Carbon DatingCarbon Dating

Dinner and a movie usually works! Just Dinner and a movie usually works! Just kidding.kidding.

Can only be used to find the age of recent Can only be used to find the age of recent fossils due to half-life of C-14 = 5,600 yrsfossils due to half-life of C-14 = 5,600 yrs

Any fossil older than 50,000 must be Any fossil older than 50,000 must be estimated using the surrounding rocks that estimated using the surrounding rocks that contain Uranium-238 and other radioactive contain Uranium-238 and other radioactive isotopes that have longer half-livesisotopes that have longer half-lives

Continental DriftContinental Drift

Continents aren’t locked into placeContinents aren’t locked into place Landmasses on different plates change Landmasses on different plates change

position relative to each other as a result of position relative to each other as a result of continental driftcontinental drift

Solution to many biological puzzlesSolution to many biological puzzles Matching fossils in totally different locationsMatching fossils in totally different locations Differing plants in locations that became isolatedDiffering plants in locations that became isolated

2 Major Events2 Major Events

1. 250 million years ago, near end of Paleozoic Era1. 250 million years ago, near end of Paleozoic Era Plates moved = 1 supercontinent = PangeaPlates moved = 1 supercontinent = Pangea Variety of changesVariety of changes

Shoreline reducedShoreline reduced Sea levels droppedSea levels dropped Shallow coastal seas were drained, destroying shallow water Shallow coastal seas were drained, destroying shallow water

environments and inhabiting speciesenvironments and inhabiting species Continental interiors influenced as wellContinental interiors influenced as well Isolated, evolving species came together and competed = cause Isolated, evolving species came together and competed = cause

mass extinctionsmass extinctions

2 Major Events (cont.)2 Major Events (cont.)

2. 180 Million years ago = Continental Drift2. 180 Million years ago = Continental Drift Pangea broke upPangea broke up Each continent became isolated Each continent became isolated Species on each continent diverged in their Species on each continent diverged in their

evolution and adapted and diversified based on evolution and adapted and diversified based on new, separate continentsnew, separate continents

Mass ExtinctionsMass Extinctions

Long periods of relative stability broken by brief Long periods of relative stability broken by brief periods of great species lossperiods of great species loss

Extinction of dinosaurs (end of Cretaceous Period – Extinction of dinosaurs (end of Cretaceous Period – 65 million years ago)65 million years ago) Climate was coolingClimate was cooling Shallow seas recedingShallow seas receding Large meteor hit Yucatan Peninsula in Mexico during same Large meteor hit Yucatan Peninsula in Mexico during same

time, sending dust into the atmospheretime, sending dust into the atmosphere Blocked sunlightBlocked sunlight Reduced food production by photosynthesisReduced food production by photosynthesis

The Positive to Mass Extinction:The Positive to Mass Extinction:

Adaptive radiation of Adaptive radiation of survivorssurvivors

In aftermath, biological In aftermath, biological diversity increased againdiversity increased again

Gives surviving organisms Gives surviving organisms new opportunitiesnew opportunities Rise of mammals may have Rise of mammals may have

resulted from the void left by resulted from the void left by the extinction of dinosaursthe extinction of dinosaurs

Taxonomy Relfects Evolutionary Taxonomy Relfects Evolutionary HistoryHistory

Identification, naming, and classification of Identification, naming, and classification of speciesspecies

Common names cause confusionCommon names cause confusion Common name can refer to many different speciesCommon name can refer to many different species Doesn’t reflect organismDoesn’t reflect organism

Universal scientific name needed for all Universal scientific name needed for all scientists to clearly communicatescientists to clearly communicate

LinneusLinneus

Binomial Nomenclature = two-part Latin Binomial Nomenclature = two-part Latin naming system for naming each species naming system for naming each species

Also a hierarchy of species into broader and Also a hierarchy of species into broader and broader groupsbroader groups

Genus + species Genus + species (Ex. (Ex. Panthera pardusPanthera pardus)) Closely related species are grouped into same Closely related species are grouped into same

genusgenus

Classification and EvolutionClassification and Evolution

Phylogenetic Tree reflects the hypotheses of Phylogenetic Tree reflects the hypotheses of evolutionary relationships evolutionary relationships Homologous structuresHomologous structures Basic underlying similarities if evolved from Basic underlying similarities if evolved from

single structure in a common ancestorsingle structure in a common ancestor Greater number of homologous structures = more Greater number of homologous structures = more

closely the species are thought to be relatedclosely the species are thought to be related

Convergent EvolutionConvergent Evolution

Not all structures are inherited from common Not all structures are inherited from common ancestorancestor

Unrelated species from similar environments Unrelated species from similar environments have adaptations that seem very similar = have adaptations that seem very similar = analogous structuresanalogous structures Wings of insects and birds = evolved Wings of insects and birds = evolved

independently despite both are flight equipment independently despite both are flight equipment and built from entirely different structuresand built from entirely different structures

Theories of EvolutionTheories of Evolution

Early 1800’sEarly 1800’s Jean Baptiste Lamarck attempted to explain Jean Baptiste Lamarck attempted to explain

Buffon’s observationsBuffon’s observations Proposed that life evolves/changesProposed that life evolves/changes Species are not permanentSpecies are not permanent Evolution is a process of adaptationEvolution is a process of adaptation Today – unfairly remembered for mistaken Today – unfairly remembered for mistaken

explanation of how adaptations evolve (make sure explanation of how adaptations evolve (make sure you know what these are – pg. 293)you know what these are – pg. 293)

DarwinDarwin

Voyage of the Voyage of the BeagleBeagle December 1831December 1831

Mission – chart poorly known stretches of the S. Mission – chart poorly known stretches of the S. American coastline for the British navyAmerican coastline for the British navy

Charles Darwin, 22, was on the shipCharles Darwin, 22, was on the ship Interested in studying geology, plants, animals Interested in studying geology, plants, animals

encountered on voyageencountered on voyage Pivotal trip in that it changed the thinking of manyPivotal trip in that it changed the thinking of many

Darwin (cont.)Darwin (cont.)

Darwin’s ObservationsDarwin’s Observations Darwin spent a lot of time on shore while Darwin spent a lot of time on shore while

ship’s crew surveyedship’s crew surveyed Collected many species of plants and animalsCollected many species of plants and animals Documented everything in extensive journals Documented everything in extensive journals

(observations, studies, personal thoughts)(observations, studies, personal thoughts) Journals documented Darwin’s thoughts from Journals documented Darwin’s thoughts from

before the journey until he returned to port in before the journey until he returned to port in EnglandEngland

Darwin (cont.)Darwin (cont.)

Darwin’s Observations (cont.)Darwin’s Observations (cont.) Noticed that plants and animals all had definite S. Noticed that plants and animals all had definite S.

Am. CharacterAm. Character Distinct from species in EuropeDistinct from species in Europe Deduced that species in S. Am. descended from Deduced that species in S. Am. descended from

ancestral species on that continentancestral species on that continent Intrigued by life on GalIntrigued by life on Galáápagos Islandpagos Island

Species were similar to plants and animals on nearest Species were similar to plants and animals on nearest mainland (not exactly same)mainland (not exactly same)

Allowed Darwin to suggest that species that left the Allowed Darwin to suggest that species that left the mainland adapted to new lives on islandsmainland adapted to new lives on islands

Darwin (cont.)Darwin (cont.)

Ideas from GeologyIdeas from Geology Darwin read a lot despite pukingDarwin read a lot despite puking

Read from Lyell’s writingsRead from Lyell’s writings Proposed that gradual and observable geologic Proposed that gradual and observable geologic

processes (erosion) could explain the physical features processes (erosion) could explain the physical features of today’s Earthof today’s Earth

River erosion = deep, river-carved canyonRiver erosion = deep, river-carved canyon Mountain range rises = earthquakesMountain range rises = earthquakes

Still Darwin…Still Darwin…

Ideas from Geology (cont.)Ideas from Geology (cont.) Darwin personally experienced an earthquake in Darwin personally experienced an earthquake in

Andes MountainsAndes Mountains He collected fossils of ocean organisms high in the He collected fossils of ocean organisms high in the

AndesAndes Concluded that (based on Lyell’s work) that the Concluded that (based on Lyell’s work) that the

earthquakes gradually lifted the rock.earthquakes gradually lifted the rock. 2 conclusions:2 conclusions:

1.1. Slow processes of mountain building and erosion suggested an Slow processes of mountain building and erosion suggested an Earth that must be very coldEarth that must be very cold

2.2. These slow and gradual processes occurring over vast spans of These slow and gradual processes occurring over vast spans of time could cause enormous change on Earthtime could cause enormous change on Earth

Darwin (cont.)Darwin (cont.)

Darwin was at sea for 5 yearsDarwin was at sea for 5 years Over this time he sent letters and specimens back Over this time he sent letters and specimens back

to Englandto England This established his reputation with other scientistsThis established his reputation with other scientists Left as young graduateLeft as young graduate Returned as a famous naturalistReturned as a famous naturalist

After analysis of his data, he became convinced that After analysis of his data, he became convinced that Earth was ancient and that species change through Earth was ancient and that species change through time.time.

Darwin (cont.)Darwin (cont.)

Thomas Malthus (wrote essay few decades Thomas Malthus (wrote essay few decades before Darwin)before Darwin) Contended that much of human suffering was due Contended that much of human suffering was due

to the human population’s potential to growto the human population’s potential to grow Populations grow IF food supplies and other resources Populations grow IF food supplies and other resources

can be producedcan be produced If this does not happen = it is a struggle for existenceIf this does not happen = it is a struggle for existence

This helped Darwin to propose a mechanism of This helped Darwin to propose a mechanism of evolutionary change.evolutionary change.

Darwin (cont.)Darwin (cont.)

Darwin’s essay (1844)Darwin’s essay (1844) 200 pages200 pages Didn’t release it to the public Didn’t release it to the public Colleagues urged Darwin to publish before someone else Colleagues urged Darwin to publish before someone else

diddid Alfred Wallace (1858) came to same conclusion and wrote Alfred Wallace (1858) came to same conclusion and wrote

to Darwin explaining his findingsto Darwin explaining his findings Within a month, both had findings presented to public Within a month, both had findings presented to public

together together Darwin published Darwin published The Origin of Species The Origin of Species about a year laterabout a year later

Darwin’s 2 PointsDarwin’s 2 Points

Darwin made 2 main points in his bookDarwin made 2 main points in his book1.1. He argued from evidence that the species of He argued from evidence that the species of

organisms living on Earth today descended from organisms living on Earth today descended from ancestral speciesancestral species

1.1. Life has a history of changeLife has a history of change

2.2. Descendants of the earliest organisms spread into Descendants of the earliest organisms spread into various habitats over millions of yearsvarious habitats over millions of years

1.1. Accumulated different modifications = “Descent with Accumulated different modifications = “Descent with Modification”Modification”

2.2. Accounts for diversity of lifeAccounts for diversity of life

Darwin’s 2 Points (cont.)Darwin’s 2 Points (cont.)

Darwin’s 2Darwin’s 2ndnd point point His argument for natural selection was the His argument for natural selection was the

mechanism for evolutionmechanism for evolution Natural selection can cause a population to change Natural selection can cause a population to change

over timeover time Result = adaptation Result = adaptation

Evolution in ProcessEvolution in Process

Homologous vs. Analogous Structures (evidence of Homologous vs. Analogous Structures (evidence of evolution)evolution)

HomologousHomologous = similar features that originated in a = similar features that originated in a shared ancestor (see page 289 in your text)-or-shared ancestor (see page 289 in your text)-or-complete online activity 14.2 in complete online activity 14.2 in Exploring LifeExploring Life Look different but have similar skeletal structureLook different but have similar skeletal structure Derive from same structures in embryoDerive from same structures in embryo

AnalogousAnalogous = serve identical functions and look = serve identical functions and look somewhat alikesomewhat alike Very different embryological developmentVery different embryological development

Look at t his picture…Look at t his picture…

Other Evidence of EvolutionOther Evidence of Evolution Vestigial StructuresVestigial Structures – features seem to serve – features seem to serve

no useful function now (human’s tailbone) but no useful function now (human’s tailbone) but may have done so historicallymay have done so historically

Similarities in EmbryologySimilarities in Embryology – See page 291, – See page 291, Figure 15-9Figure 15-9 Ernst Haeckel – embryological development Ernst Haeckel – embryological development

repeats evolutionary history! (slightly exaggerated; repeats evolutionary history! (slightly exaggerated; similarities fade as development proceeds)similarities fade as development proceeds)

Similarities in MacromoleculesSimilarities in Macromolecules - homologous - homologous proteins; RNA and DNA; amino acid sequence proteins; RNA and DNA; amino acid sequence is similar between different speciesis similar between different species

Patterns of EvolutionPatterns of Evolution

CoevolutionCoevolution – change of 2 or more species in close – change of 2 or more species in close association with each otherassociation with each other Predators and their prey; parasites and hosts; plant-eating Predators and their prey; parasites and hosts; plant-eating

animals and their chosen plantanimals and their chosen plant Convergent EvolutionConvergent Evolution – Organisms appear to be – Organisms appear to be

similar but are not closely related at all – analogous similar but are not closely related at all – analogous structures are similar adaptations that result from this structures are similar adaptations that result from this

Divergent EvolutionDivergent Evolution – 2 or more related populations – 2 or more related populations become more and more dissimilarbecome more and more dissimilar Adaptive radiationAdaptive radiation Artificial selectionArtificial selection

Adaptive RadiationAdaptive Radiation

Artificial selection…Artificial selection…