ORIGIN OF LIFE Theories Past and Present Nature of Early Cells Evolution of Cells River Dell High School Biology

ORIGIN OF LIFEORIGIN OF LIFETheories Past and PresentTheories Past and Present

Nature of Early CellsNature of Early CellsEvolution of CellsEvolution of Cells

River Dell High SchoolRiver Dell High SchoolBiologyBiology

Main QUESTIONSMain QUESTIONSWhat is evolution and how do we determine What is evolution and how do we determine evolutionary relationships?evolutionary relationships?

Where does variation come from and what role Where does variation come from and what role does it play in evolution?does it play in evolution?

Is there one best way to be?Is there one best way to be?

Which wolf activity…Which wolf activity…– Describe your wolf (physically and behaviorally)Describe your wolf (physically and behaviorally)– What is good about it? What is good about it? – What are its disadvantages?What are its disadvantages?

EVOLUTIONEVOLUTION

The idea that over time things change in The idea that over time things change in response to the environment.response to the environment.

Variation is at the heart of evolution because Variation is at the heart of evolution because there is there is no one best way to be all the timeno one best way to be all the time..

Where does this variation come from?Where does this variation come from?– MeiosisMeiosis– Sexual reproductionSexual reproduction– Crossing over and independent assortmentCrossing over and independent assortment– mutationsmutations

EVIDENCEEVIDENCE

The evidence we gather to determine these The evidence we gather to determine these evolutionary relationships come from evolutionary relationships come from observing the similarities and differences observing the similarities and differences of and today’s living organisms and those of and today’s living organisms and those that used to be living.that used to be living.

I. Evidence of EvolutionI. Evidence of EvolutionA. FossilsA. Fossils

1. Definition - trace or remains of 1. Definition - trace or remains of organisms that are preservedorganisms that are preserved 2. types2. types a. a. moldmold (rock imprint) (rock imprint) b. b. castcast (mold that is filled) (mold that is filled) c. c. petrified (converted into petrified (converted into

stone/mineral)stone/mineral) d. preserved in d. preserved in amberamber or or tar pitstar pits

Mold Fossil Cast FossilMold Fossil Cast Fossil

Fossil in AmberFossil in Amber Petrified WoodPetrified Wood

Dinosaur Fossils Toe of a DinosaurDinosaur Fossils Toe of a Dinosaur

I. I. Evidence of EvolutionEvidence of EvolutionA. FossilsA. Fossils

3. location3. location

a. sedimentary rocka. sedimentary rock

b. amber or tar pitsb. amber or tar pits

4. distribution4. distribution

aa..Law of SuperpositionLaw of Superposition(Steno 1638-1686)(Steno 1638-1686)

1) 1) relative agerelative age

2) 2) absolute ageabsolute age

b. b. Biogeography (study of location of Biogeography (study of location of organisms around the world)organisms around the world)

Fossils Are Found in Tar PitsFossils Are Found in Tar Pits

Sedimentary Sedimentary Rock Showing Rock Showing

LayersLayers

Law of Law of SuperpositionSuperposition – – younger fossils younger fossils are closer to the are closer to the surface – older surface – older fossils are deeperfossils are deeper

IV. Radioactive Decay and DatingIV. Radioactive Decay and Dating

A.A. Isotope Isotope – atoms of the same element – atoms of the same element that differ in the number of neutronsthat differ in the number of neutrons

B.B. Radioactive decay Radioactive decay – process in which – process in which unstable nuclei release particles and/or unstable nuclei release particles and/or energy until they are stableenergy until they are stable

C.C. Half-life Half-life – the length of time it takes for ½ – the length of time it takes for ½ any amount of a radioactive isotope to any amount of a radioactive isotope to decay decay

Half-livesHalf-lives256 14C atoms at time 0

---------------------------128 14C and

128 14N atoms

after 5,600 years or

1 half-life

-----------------------------64 14C and

192 14N atoms


2 half-lives

Half-livesHalf-lives 32 14C and

224 14N atoms


3 half-lives

------------------------------16 14C and

240 14N atoms


4 half-lives

-----------------------------8 14C and

248 14N atoms


5 half-lives

Half-livesHalf-lives4 14C and

252 14N atoms


6 half-lives

----------------------------------

2 14C and

254 14N atoms


7 half-lives

The The half-lifehalf-life of C-14 is 5,600 years and a sample of C-14 is 5,600 years and a sample today has 1,000 C-14 atoms, after 5,600 years today has 1,000 C-14 atoms, after 5,600 years

500 C-14 atoms will remain (1/2 original amount) 500 C-14 atoms will remain (1/2 original amount)

After two half lives (11,200 years) After two half lives (11,200 years) 250 C-14 atoms will remain (1/4 original amount)250 C-14 atoms will remain (1/4 original amount)

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I. Evidence of EvolutionI. Evidence of EvolutionB. Comparative AnatomyB. Comparative Anatomy

1. 1. homologous structureshomologous structures a. similar structure, evolution, a. similar structure, evolution, developmentdevelopment b. wing, arm, flipperb. wing, arm, flipper 2. 2. analogous structuresanalogous structures a. similar functiona. similar function b. wing of a bird and an insectb. wing of a bird and an insect

Homologous vs Analogous StructuresHomologous vs Analogous Structures

I. Evidence of EvolutionI. Evidence of EvolutionB. Comparative AnatomyB. Comparative Anatomy

3. 3. vestigial structuresvestigial structures

a. useful in past organisms but not a. useful in past organisms but not

nownow

b. appendix, tail vertebrae, b. appendix, tail vertebrae,

ear musclesear muscles

Vestigial StructuresVestigial Structures Appendix in Humans Leg Bones in a Whale Appendix in Humans Leg Bones in a Whale

I. Evidence of EvolutionI. Evidence of EvolutionC. Embryology SimilaritiesC. Embryology Similarities

1. 1. Haeckel(1834-1919) [German]Haeckel(1834-1919) [German]

a. “ontogeny recapitulate phylogeny”a. “ontogeny recapitulate phylogeny”

1) embryo undergoes changes 1) embryo undergoes changes

that repeat evolutionary that repeat evolutionary

developmentdevelopment

Diagram Showing Similarities in Early Diagram Showing Similarities in Early Stages of Embryo DevelopmentStages of Embryo Development

I.I. Evidence of EvolutionEvidence of EvolutionD. BiochemistryD. Biochemistry

1. similarity in amino acids in specific 1. similarity in amino acids in specific

proteinsproteins

2. similarity in RNA and DNA base 2. similarity in RNA and DNA base

sequencessequences

Comparing Amino Acid Differences of Comparing Amino Acid Differences of Several Organisms to HumansSeveral Organisms to Humans

II. Theories of EvolutionII. Theories of EvolutionA. Lamark (1744-1829)A. Lamark (1744-1829)

1.1. Acquired traits – Acquired traits – traits that traits that develop during one generationdevelop during one generation can be passed to the next can be passed to the next generationgeneration 2. 2. Law of Use and DisuseLaw of Use and Disuse – if a trait – if a trait is not used it will be lostis not used it will be lost

““use it or lose it” mentality….use it or lose it” mentality….

Lamarck and Law of Use and DisuseLamarck and Law of Use and Disuse

According to According to Lamarck the Lamarck the giraffes pictured giraffes pictured grew longer necks grew longer necks in order to reach in order to reach the leaves in taller the leaves in taller treestrees

The longer necks The longer necks were then passed were then passed to the next to the next generationgeneration

II. Theories of EvolutionII. Theories of EvolutionB. Charles Darwin(1809-1882)B. Charles Darwin(1809-1882)

1. Biography1. Biography a. Darwin attended medical schoola. Darwin attended medical school b. studied to be a clergymanb. studied to be a clergyman c. 22 years old - signed on c. 22 years old - signed on HMS BeagleHMS Beagle 1) collect specimens as a naturalist1) collect specimens as a naturalist 2) refined data for 21 years2) refined data for 21 years

Charles Darwin Darwin’s HomeCharles Darwin Darwin’s Home

HMS BeagleHMS Beagle in Sydney Australia Harbor in Sydney Australia Harbor

Darwin’s VoyageDarwin’s Voyage

Darwin’s FinchesDarwin’s Finches


2. 2. The Origin of SpeciesThe Origin of Species (1859) (1859)

a.a. Descent with modificationDescent with modification

1) all species descend from a 1) all species descend from a

small number of original typessmall number of original types

2) there is variation among 2) there is variation among

organismsorganisms

http://www.talkorigins.org/faqs/origin.html


b. b. Modification by SelectionModification by Selection

1) 1) environment limits growth of populationsenvironment limits growth of populations

-competition for life’s necessities-competition for life’s necessities

-specific traits are selected-specific traits are selected

2) 2) adaptive advantageadaptive advantage

- trait favorable for a given environment- trait favorable for a given environment

- adaptations make some organisms - adaptations make some organisms

more likely to survive than othersmore likely to survive than others

II. Theories of EvolutionII. Theories of EvolutionB. Darwin’s termsB. Darwin’s terms

3) 3) fitnessfitness - ability of an organism to - ability of an organism to

make a genetic contribution to themake a genetic contribution to the

next generationnext generation

4) 4) natural selectionnatural selection allows individuals allows individuals

with survival adaptations to pass with survival adaptations to pass

traits to offspringtraits to offspring

II. Theories of EvolutionII. Theories of Evolution

5) 5) speciationspeciation - formation of new - formation of new species as favorable adaptations species as favorable adaptations accumulate (butterfly- white/black)accumulate (butterfly- white/black)

6) 6) “survival of the fittest”“survival of the fittest” - those - those organisms with favorable traits organisms with favorable traits reproduce and pass their traits to reproduce and pass their traits to future generationsfuture generations

Darwin’s theory in a nutshellDarwin’s theory in a nutshellOverproduction of OrganismsOverproduction of OrganismsVariation in organismsVariation in organismsCompetition to surviveCompetition to surviveSome characteristics increase chances for Some characteristics increase chances for survival and reproductionsurvival and reproductionThese characteristics allow organisms with them These characteristics allow organisms with them (Fit organisms) to reproduce better than others (Fit organisms) to reproduce better than others (which will die out and not pass on genes)(which will die out and not pass on genes) Good characteristics will get passed on as Good characteristics will get passed on as organisms “evolve” to have the trait.organisms “evolve” to have the trait.Maybe forms new species? (speciation)Maybe forms new species? (speciation)

III. Patterns of EvolutionIII. Patterns of EvolutionA. A. CoevolutionCoevolution

1. changes in two or more species 1. changes in two or more species

closely associatedclosely associated

2. examples2. examples

a. predator and preya. predator and prey

b. parasite and hostb. parasite and host

c. plants and plant pollinatorsc. plants and plant pollinators

III. Patterns of Evolution III. Patterns of Evolution B. Convergent EvolutionB. Convergent Evolution

1. similar phenotypes are selected (b/c of 1. similar phenotypes are selected (b/c of environment) but ancestors are very environment) but ancestors are very differentdifferent

a. natural selection of analogous a. natural selection of analogous

structures because of envir. demands.structures because of envir. demands.

2. examples2. examples

a. wings in insects and birdsa. wings in insects and birds

b. fins & shape of sharks, fish, porpoiseb. fins & shape of sharks, fish, porpoise

Examples of Convergent EvolutionExamples of Convergent Evolution

III. Patterns of EvolutionIII. Patterns of EvolutionC. Divergent EvolutionC. Divergent Evolution

1. two or more related populations or 1. two or more related populations or

species become more dissimilarspecies become more dissimilar

a. a. speciationspeciation - new species may form - new species may form

2. example 2. example geographic isolationgeographic isolation

a. brown bear a. brown bear polar bear polar bear

III. Patterns of EvolutionIII. Patterns of EvolutionC. Divergent EvolutionC. Divergent Evolution

3. 3. adaptive radiationadaptive radiation

a. many species evolve from same a. many species evolve from same

ancestorancestor

1) ancestor migrates to different 1) ancestor migrates to different

environments (example) -environments (example) -

Galapagos finchesGalapagos finches

Adaptive Radiation – Darwin’s FinchesAdaptive Radiation – Darwin’s Finches

Beak shape Depends Upon Food SourceBeak shape Depends Upon Food Source

Adaptive Radiation – Hawaiian HoneycreepersAdaptive Radiation – Hawaiian Honeycreepers

IV. Variation in PopulationsIV. Variation in PopulationsA. Distribution of variationsA. Distribution of variations 1. graph is a bell curve 1. graph is a bell curve B. Natural Selection and Changes in B. Natural Selection and Changes in PopulationsPopulations 1. 1. Stabilizing SelectionStabilizing Selection – favors average– favors average formform 2. 2. Directional SelectionDirectional Selection – average shifts– average shifts to one extreme or the otherto one extreme or the other 3. 3. Disruptive Selection Disruptive Selection – extreme forms – extreme forms are favored- number of individuals are favored- number of individuals withwith thethe average form is reducedaverage form is reduced

Stabilizing SelectionStabilizing Selection

Directional SelectionDirectional Selection

Disruptive SelectionDisruptive Selection

V. Speciation and Rate of EvolutionV. Speciation and Rate of Evolution

A. A. SpeciesSpecies - organisms that are - organisms that are

morphologically similar and can morphologically similar and can interbreed to produce fertile offspringinterbreed to produce fertile offspring

SpeciationSpeciation - process of forming - process of forming

speciesspecies

V. Speciation and Rate of EvolutionV. Speciation and Rate of EvolutionA. Species and SpeciationA. Species and Speciation

2. 2. Isolating mechanismsIsolating mechanisms that result in that result in

speciationspeciation

a) a) geographic barriersgeographic barriers separate populations separate populations

1) 1) gene flowgene flow stops and natural selection stops and natural selection

and genetic drift result in divergenceand genetic drift result in divergence

b) b) reproductive barriersreproductive barriers - prevent breeding - prevent breeding

of organisms in the same geographic areaof organisms in the same geographic area

V. Speciation and Rate of EvolutionV. Speciation and Rate of EvolutionB. Rate of EvolutionB. Rate of Evolution

2. 2. GradualismGradualism (Darwin) - new species arise (Darwin) - new species arise slowly and continuously through small, slowly and continuously through small, gradual changesgradual changes

3. 3. Punctuated EquilibriumPunctuated Equilibrium (Steven Gould (Steven Gould and Niles Eldredge) - there are long and Niles Eldredge) - there are long periods (up to millions of years) with little periods (up to millions of years) with little or no change - then there is a short period or no change - then there is a short period of rapid change of rapid change

SO WHERE THE VARIATION SO WHERE THE VARIATION EVOLUTION ACTS UPON COME EVOLUTION ACTS UPON COME

FROM???FROM???

ANDAND

WHAT CAUSES CHANGES IN WHAT CAUSES CHANGES IN POPULATIONS OVER TIME??POPULATIONS OVER TIME??

Variation in PopulationsVariation in PopulationsC. Genetic Sources of VariationC. Genetic Sources of Variation

11. . MutationsMutations

a) a specific gene mutates in a) a specific gene mutates in

1/10,0000 gametes1/10,0000 gametes

b) thousands of genes in each gameteb) thousands of genes in each gamete

c) some mutations in every zygotec) some mutations in every zygote

d) most mutations are recessived) most mutations are recessive

2. 2. Recombination Recombination a) random meeting of sperm and egga) random meeting of sperm and egg b) crossing over during meiosisb) crossing over during meiosis

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ORIGIN OF LIFE Theories Past and Present Nature of Early Cells Evolution of Cells River Dell High School Biology