Key Thinking Skills of Evolution for TodayKey Thinking Skills of Evolution for Today • These key thinking skills will be used today as we go through the

lesson on biodiversity and biological evolution. Keep the following questions in mind as we go through the material.

– Details

• What features characterize biodiversity and biological evolution?

– Language of the Discipline

• What terms or words are specific to the study of biodiversity and biological evolution?

Essential Question & TermsEssential Question & Terms• Essential Question:

– Be able to describe how the earth is “just right” for life.

– What is evolution?

– How has evolution lead to the current diversity of organisms?

– What is an ecological niche?

– How does it relate to adaptation to changing environmental conditions?

– How do extinction of species and formation of new species affect biodiversity?

• Terms:– Biodiversity– Biological evolution– Extinction– Chemical evolution– Natural selection– Adaptation– Prokaryotic cells– Eukaryotic cells– Gradualism

punctuated equilibrium– Kingdoms– Background extinction– Mass extinction– Adaptive radiation

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What types of Life What types of Life exist on the Earth? exist on the Earth?

Ingredients for Life: Carbon

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Types of OrganismsTypes of Organisms

• Prokaryotic KingdomProkaryotic Kingdom: : single-single-celled organisms containing no celled organisms containing no internal structures surrounded by internal structures surrounded by membranes (therefore there is no membranes (therefore there is no nucleus) nucleus) – MoneraMonera – bacteria and – bacteria and

cyanobacteriacyanobacteria

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Aerobic bacteria

Ancient Prokaryotes

Ancient Anaerobic Prokaryote

Primitive Aerobic Eukaryote

Primitive Photosynthetic Eukaryote

Chloroplast

Photosynthetic bacteriaNuclear

envelope evolving Mitochondrion

Plants and plantlike protists

Animals, fungi, and non-plantlike protists

Endosymbiotic TheoryEndosymbiotic Theory

• argues that mitochondria, plastids (e.g. chloroplasts), and possibly other organelles of eukaryotic cells, originate through symbiosis between multiple microorganisms.

• According to this theory, certain organelles originated as free-living bacteria that were taken inside another cell as endosymbionts.

• Mitochondria developed from proteobacteria and chloroplasts from cyanobacteria.

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Types of OrganismsTypes of Organisms• Eukaryotic KingdomsEukaryotic Kingdoms: : all organisms consisting of all organisms consisting of

cells which contain membrane-bound nucleicells which contain membrane-bound nuclei– ProtistaProtista - mostly - mostly one-celled organisms – have one-celled organisms – have

characteristics of all three other Eukaryote Kingdomscharacteristics of all three other Eukaryote Kingdoms

– FungiFungi - - organisms which decompose stufforganisms which decompose stuff

– PlantaePlantae - - organisms which use photosynthesis to make organisms which use photosynthesis to make their own food their own food

• AnnualsAnnuals complete complete life cycle in one seasonlife cycle in one season

• PerennialsPerennials live for more than one seasonlive for more than one season

– AnimaliaAnimalia - - organisms which must get organic compounds organisms which must get organic compounds from food they eat - most are able to movefrom food they eat - most are able to move

• InvertebratesInvertebrates – – no backboneno backbone

• VertebratesVertebrates – – Fish, Amphibians, Reptiles, Birds and Fish, Amphibians, Reptiles, Birds and MammalsMammals

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How did Life How did Life Originate?Originate?

OrOrChemical EvolutionChemical Evolution

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EVOLUTIONEVOLUTIONisis

Gradual ChangeGradual Change

EVOLUTIONEVOLUTIONisis

Gradual ChangeGradual Change

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EvidenceEvidenceEvolution in ActionWatch!

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FossilsFossils1600's - Danish scientist Nicholas Steno studied 1600's - Danish scientist Nicholas Steno studied the relative positions of sedimentary rocksthe relative positions of sedimentary rocks

– LayeringLayering is the most obvious feature of sedimentary is the most obvious feature of sedimentary rocksrocks

• formed particle by particle and bed by bed, and the layers formed particle by particle and bed by bed, and the layers are piled one on top of the otherare piled one on top of the other

• any sequence of layered rocks, a given bed must be older any sequence of layered rocks, a given bed must be older than any bed on top of itthan any bed on top of it

– Law of SuperpositionLaw of Superposition is fundamental to the is fundamental to the interpretation of Earth history, because at any one interpretation of Earth history, because at any one location it indicates the relative ages of rock layers location it indicates the relative ages of rock layers and the fossils in them. and the fossils in them.

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Half-life for a given radioisotope is the time for half the Half-life for a given radioisotope is the time for half the radioactive nuclei in any sample to undergo radioactive nuclei in any sample to undergo

radioactive decayradioactive decay

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Biological Biological EvolutionEvolution

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Evolutionary BushEvolutionary BushEvolutionary BushEvolutionary BushOne life-form splits into two One life-form splits into two and those branches split and those branches split (independently) to make (independently) to make more.more.

One life-form splits into two One life-form splits into two and those branches split and those branches split (independently) to make (independently) to make more.more.

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Phenotypic Phenotypic ‘distance’‘distance’

Phenotypic Phenotypic ‘distance’‘distance’

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Evolutionary Bush -- Evolutionary Bush -- thousands of earlier and thousands of earlier and later branches.later branches.

Evolutionary Bush -- Evolutionary Bush -- thousands of earlier and thousands of earlier and later branches.later branches.

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At any given moment (e.g. the At any given moment (e.g. the ‘present’), all we see is ‘present’), all we see is current current

diversitydiversity……all all extinctextinct forms are gone (99.9%) forms are gone (99.9%)

At any given moment (e.g. the At any given moment (e.g. the ‘present’), all we see is ‘present’), all we see is current current

diversitydiversity……all all extinctextinct forms are gone (99.9%) forms are gone (99.9%)

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Tim

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Tim

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Tim

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Charles Darwin• 1809-1882

• British naturalist

• Proposed the idea of evolution by natural selection

• Collected clear evidence to support his ideas

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Darwin’s ObservationsDarwin’s Observations1.1. Most species produce more offspring Most species produce more offspring

than can be supported by the than can be supported by the environmentenvironment

2.2. Environmental resources are limitedEnvironmental resources are limited3.3. Most populations are stable in sizeMost populations are stable in size4.4. Individuals vary greatly in their Individuals vary greatly in their

characteristics (phenotypes)characteristics (phenotypes)5.5. Variation is heritable (genotypes)Variation is heritable (genotypes)

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Darwin’s finchesDarwin’s finches• 13 species of finches in the Galápagos

Islands• Was puzzling since only 1 species of this

bird on the mainland of South America, 600 miles to the east, where they had all presumably originated

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Darwin’s finchesDarwin’s finches

• Differences in beaks – associated with eating different foods– adaptations to the foods available on their home

islands

• Darwin concluded that when the original South American finches reached the islands, they adapted to available food in different environments

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What did Darwin say?What did Darwin say?• Organisms reproduce more than the

environment can support– some offspring survive– some offspring don’t survive– competition

• for food• for mates• for nesting spots• to get away

from predators

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Survival of the fittestSurvival of the fittest• Who is the fittest?

–traits fit the environment

–the environment can change, so who is fit can change

Peppered moth

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Stephen Jay Gould Stephen Jay Gould (1941-2002)(1941-2002)

• Harvard paleontologist & evolutionary biologist– punctuated equilibrium– prolific author

• popularized evolutionary thought

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Punctuated EquilibriumPunctuated Equilibrium

• Rate of speciation is not constant– rapid bursts of

change – long periods of little

or no change– species undergo

rapid change when they 1st bud from parent population Time

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Gradualism Gradualism

Gradual divergence Gradual divergence over long spans of timeover long spans of time

– assume that big assume that big changes occur as the changes occur as the accumulation of many accumulation of many small onessmall ones

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Adaptive RadiationAdaptive Radiation• When one species splits into many

species to fill open habitats.– Darwin’s finches

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Speciation• One species can evolve into two or

more species

• 2 step process– Geographical isolation

– Reproductive isolation

When a group becomes geographically isolated over time

it will become reproductively isolated = new species formed.

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Geographic isolationGeographic isolation•When a population becomes divided by a natural barrier.

•Mountains, river, body of water, landslides•Groups can’t interbreed or intermix•Become adapted to a different environment

Harris’s antelope squirrel inhabits the canyon’s south rim (L). Just a few miles away on the north rim (R) lives the closely related white-tailed antelope squirrel

Harris’s antelope squirrel inhabits the canyon’s south rim (L). Just a few miles away on the north rim (R) lives the closely related white-tailed antelope squirrel

Ammospermophilus spp

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Reproductive IsolationReproductive Isolation• Differences in isolated groups become so

great, they can no longer interbreed– Physical changes

– Behavioral changes

– Biochemical changes

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SpeciationSpeciation

Evolution of new speciesEvolution of new species

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Four causes of evolutionary Four causes of evolutionary change:change:Four causes of evolutionary Four causes of evolutionary change:change:

1.1. MutationMutation:: fundamental origin of fundamental origin of allall genetic genetic (DNA) change.(DNA) change.

1.1. MutationMutation:: fundamental origin of fundamental origin of allall genetic genetic (DNA) change.(DNA) change.

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Four causes of evolutionary Four causes of evolutionary change:change:Four causes of evolutionary Four causes of evolutionary change:change:

1.1. MutationMutation: fundamental genetic shifts.: fundamental genetic shifts.

2.2. Genetic DriftGenetic Drift:: isolated populations accumulate isolated populations accumulate different mutations over time.different mutations over time.

1.1. MutationMutation: fundamental genetic shifts.: fundamental genetic shifts.

2.2. Genetic DriftGenetic Drift:: isolated populations accumulate isolated populations accumulate different mutations over time.different mutations over time.

In a continuous In a continuous population, genetic population, genetic novelty can spread novelty can spread locally.locally.

In a continuous In a continuous population, genetic population, genetic novelty can spread novelty can spread locally.locally.

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Four causes of evolutionary Four causes of evolutionary change:change:Four causes of evolutionary Four causes of evolutionary change:change:

But in But in discontinuousdiscontinuous populations, populations, gene gene flowflow is blocked. is blocked.

But in But in discontinuousdiscontinuous populations, populations, gene gene flowflow is blocked. is blocked.

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Four causes of evolutionary changeFour causes of evolutionary changeFour causes of evolutionary changeFour causes of evolutionary change

1.1. MutationMutation: fundamental genetic shifts.: fundamental genetic shifts.

2.2. Genetic DriftGenetic Drift: isolation : isolation accumulate accumulate mutations mutations

3.3. Founder EffectFounder Effect:: sampling biassampling bias during during immigration. When a new population is immigration. When a new population is formed, its genetic composition depends formed, its genetic composition depends largely on the gene frequencies within the largely on the gene frequencies within the group of first settlers.group of first settlers.

1.1. MutationMutation: fundamental genetic shifts.: fundamental genetic shifts.

2.2. Genetic DriftGenetic Drift: isolation : isolation accumulate accumulate mutations mutations

3.3. Founder EffectFounder Effect:: sampling biassampling bias during during immigration. When a new population is immigration. When a new population is formed, its genetic composition depends formed, its genetic composition depends largely on the gene frequencies within the largely on the gene frequencies within the group of first settlers.group of first settlers.

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Founder Effect.--Founder Effect.--

Human example: your tribe had to Human example: your tribe had to live near the Bering land bridge…live near the Bering land bridge…

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Founder Effect.--Founder Effect.--

……to invade & settle the ‘New World’!to invade & settle the ‘New World’!

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Four causes of evolutionary change:Four causes of evolutionary change:Four causes of evolutionary change:Four causes of evolutionary change:

1.1. MutationMutation: fundamental genetic shifts.: fundamental genetic shifts.

2.2. Genetic DriftGenetic Drift: isolation : isolation accumulation of accumulation of mutations mutations

3.3. Founder EffectFounder Effect: immigrant sampling bias. : immigrant sampling bias.

4.4. Natural SelectionNatural Selection: differential : differential reproduction of individuals in the same reproduction of individuals in the same population based on genetic differences population based on genetic differences among them.among them.

1.1. MutationMutation: fundamental genetic shifts.: fundamental genetic shifts.

2.2. Genetic DriftGenetic Drift: isolation : isolation accumulation of accumulation of mutations mutations

3.3. Founder EffectFounder Effect: immigrant sampling bias. : immigrant sampling bias.

4.4. Natural SelectionNatural Selection: differential : differential reproduction of individuals in the same reproduction of individuals in the same population based on genetic differences population based on genetic differences among them.among them.

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Four causes of evolutionary Four causes of evolutionary change:change:Four causes of evolutionary Four causes of evolutionary change:change:1.1. MutationMutation: fundamental genetic shifts.: fundamental genetic shifts.

2.2. Genetic DriftGenetic Drift: isolation : isolation accumulation of accumulation of mutations mutations

3.3. Founder EffectFounder Effect: immigrant sampling bias. : immigrant sampling bias.

4.4. Natural SelectionNatural Selection: reproductive race: reproductive race

These 4 interact synergisticallyThese 4 interact synergistically

1.1. MutationMutation: fundamental genetic shifts.: fundamental genetic shifts.

2.2. Genetic DriftGenetic Drift: isolation : isolation accumulation of accumulation of mutations mutations

3.3. Founder EffectFounder Effect: immigrant sampling bias. : immigrant sampling bias.

4.4. Natural SelectionNatural Selection: reproductive race: reproductive race

These 4 interact synergisticallyThese 4 interact synergistically

Modes of ActionModes of Action

• Natural selection has three modes of action:Natural selection has three modes of action:

1.1. Stabilizing selectionStabilizing selection

2.2. Directional selectionDirectional selection

3.3. Diversifying selectionDiversifying selection

Number ofIndividuals

Size of individuals

Small Large

1.1. Stabilizing SelectionStabilizing Selection

Acts upon extremes and favors Acts upon extremes and favors the intermediatethe intermediate

Number ofIndividuals

Size of individualsSmall Large

2.2. Directional SelectionDirectional Selection

Favors variants of one extremeFavors variants of one extreme

Number ofIndividuals

Size of individualsSmall Large

3.3. Diversifying SelectionDiversifying SelectionFavors variants of opposite Favors variants of opposite

extremesextremes

Number ofIndividuals

Size of individualsSmall Large

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Evidence of Evidence of EvolutionEvolution

1. Biogeography:1. Biogeography:Geographical distribution of speciesGeographical distribution of species

2. Fossil Record:2. Fossil Record:Fossils and the order in Fossils and the order in

which they appear in layers of which they appear in layers of sedimentary rock (sedimentary rock (strongest strongest

evidenceevidence))

3. Taxonomy:3. Taxonomy:

Classification of life Classification of life forms.forms.

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4. Homologous Structures:4. Homologous Structures:Structures that Structures that are similar are similar because of because of common common ancestry ancestry (comparative (comparative anatomy)anatomy)

Turtle Alligator Bird Mammals

Typical primitive fish

5. Comparative Embryology:5. Comparative Embryology:

Study of Study of structures structures that appear that appear during during embryonic embryonic developmentdevelopment

6. Molecular Biology:6. Molecular Biology:

DNA and proteins (amino acids)DNA and proteins (amino acids)

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BibliographyBibliography1. Miller 11th Edition2. http://abandoncorporel.ca/medias/evolution.jpg3. http://www.ne.jp/asahi/clinic/yfc/fetus.html4. rob.ossifrage.net/images/ 5. http://www.mun.ca/biology/scarr/Five_Kingdoms_Three_Domains.htm6. http://www.gpc.peachnet.edu/~ccarter/Millerlec5/Millerlec5.PPT7. http://www.dnr.state.md.us/education/horseshoecrab/lifecycle.html8. http://www.falcons.co.uk/mefrg/Falco/13/Species.htm9. http://www.sms.si.edu/irlspec/NamSpecies.htm10. http://www.falcons.co.uk/mefrg/Falco/13/Species.htm11. http://www.globalchange.umich.edu/globalchange1/current/lectures/complex_life/complex_life.html12. http://nsm1.nsm.iup.edu/rwinstea/oparin.shtm13. http://www.angelfire.com/on2/daviddarling/MillerUreyexp.htm14. http://exobiology.nasa.gov/ssx/biomod/origin_of_life_slideshow/origin_of_life_slideshow.html15. http://www.geo.cornell.edu/geology/classes/Geo104/HistoryofEarth.html16. http://astrobiology.arc.nasa.gov/roadmap/objectives/o2_cellular_components.html17. http://pubs.usgs.gov/gip/fossils/18. http://hyperphysics.phy-astr.gsu.edu/hbase/nuclear/halfli.html19. http://www.accessexcellence.org/AE/AEPC/WWC/1995/teach_rad.html20. http://biology.usgs.gov/s+t/SNT/noframe/pi179.htm21. http://www.npca.org/magazine/2001/march_april/nonnative_species.asp22. http://www.bagheera.com/inthewild/spot_spkey.htm23. Biology, 2003, Prentice Hall24. http://www.nearctica.com/ecology/habitats/island.htm25. http://www.valdosta.edu/~grissino/geog4900/lect_1.htm