evolution, biodiversity, and community processes · 2009-10-15 · 14 definition of species •...

Evolution,Evolution,

Biodiversity, andBiodiversity, and

CommunityCommunity

ProcessesProcesses

La CaLa Cañada High Schoolñada High School

Dr. EDr. E

What types of LifeWhat types of Life

exist on the Earth?exist on the Earth?

Types of OrganismsTypes of Organisms

•• Prokaryotic KingdomProkaryotic Kingdom: : single-single-celled organisms containing nocelled organisms containing nointernal structures surrounded byinternal structures surrounded bymembranes (therefore there is nomembranes (therefore there is nonucleus)nucleus)

–– MoneraMonera –– bacteria and bacteria andcyanobacteriacyanobacteria

Aerobic

bacteriaAncient Prokaryotes

Ancient Anaerobic

Prokaryote

Primitive Aerobic

Eukaryote

Primitive Photosynthetic

Eukaryote

Chloroplas

Photosynthetic

bacteriaNuclear

envelope

evolving Mitochondrion

Plants and

plantlike

protists

Animals, fungi, and

non-plantlike protists

Endosymbiotic TheoryEndosymbiotic Theory

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

cells which contain membrane-bound nucleicells which contain membrane-bound nuclei

–– ProtistaProtista - mostly - mostly one-celled organisms one-celled organisms –– have 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 makeorganisms which use photosynthesis to make

their own foodtheir 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 compoundsorganisms 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 andFish, Amphibians, Reptiles, Birds and

MammalsMammals

NamingNaming

SpeciesSpecies

Naming of SpeciesNaming of Species

The system of naming species was first developed byThe system of naming species was first developed bySwedish botanist and physician, Carolus Linnaeus in theSwedish botanist and physician, Carolus Linnaeus in themid- 1700smid- 1700s

••Taxonomy, which seeks to describe, name and classify organismsTaxonomy, which seeks to describe, name and classify organisms

••begins with assigning all species a two-part Latin name called abegins with assigning all species a two-part Latin name called abinomialbinomial

••first word of the binomial is the genus name of the species,first word of the binomial is the genus name of the species,

•• second word is the specific epithet for the species. second word is the specific epithet for the species.

–– scientific name for the blue crabscientific name for the blue crab is is Callinectes sapidusCallinectes sapidus

–– CallinectesCallinectes, the genus name, is the collective term which, the genus name, is the collective term whichincludes many species of crabs closely related to the blueincludes many species of crabs closely related to the bluecrabcrab

–– sapidussapidus, describes exactly which of the , describes exactly which of the CallinectesCallinectes species is species isbeing identifiedbeing identified

Definition of SpeciesDefinition of Species

•• Morphological Species Concept (MSC)Morphological Species Concept (MSC)

–– traced back to the philosophies of Plato andtraced back to the philosophies of Plato andAristotle, and which Aristotle, and which continued to be usedcontinued to be useduntil the first half of the twentieth centuryuntil the first half of the twentieth century

–– defines species purely by their phenotypicdefines species purely by their phenotypictraits rather than their genetic complementtraits rather than their genetic complementor potential interbreedingor potential interbreeding

–– number of species classified was largenumber of species classified was largebecause each group of individuals thatbecause each group of individuals thatexhibited a slight phenotypic difference wereexhibited a slight phenotypic difference wereconsidered a different speciesconsidered a different species

http://www.falcons.co.uk/mefrg/Falco/13/Species.htmhttp://www.falcons.co.uk/mefrg/Falco/13/Species.htm

Definition of SpeciesDefinition of Species

•• Biological Species Concept (BSC)Biological Species Concept (BSC)–– ‘‘a species is a group of interbreeding populations thata species is a group of interbreeding populations that

are genetically isolated from other groups byare genetically isolated from other groups byreproductive isolating mechanisms such as hybridreproductive isolating mechanisms such as hybridsterility or mate acceptabilitysterility or mate acceptability’’

•• Phylogenetic Species Concept (PSCPhylogenetic Species Concept (PSC–– Each population of sexually reproducing organismsEach population of sexually reproducing organisms

that possesses at least one diagnostic characterthat possesses at least one diagnostic characterpresent in all population members but absent from allpresent in all population members but absent from allclosest relatives is considered a speciesclosest relatives is considered a species

–– each geographically distinct form is classified as a each geographically distinct form is classified as aspeciesspecies

http://www.falcons.co.uk/mefrg/Falco/13/Species.htmhttp://www.falcons.co.uk/mefrg/Falco/13/Species.htm

How did LifeHow did Life

Originate?Originate?

Chemical EvolutionChemical Evolution

EVOLUTIONEVOLUTION

Gradual ChangeGradual Change

Origin of LifeOrigin of Life•• 600 BC 600 BC AnaximanderAnaximander

–– life began in waterlife began in water..

–– early forms wereearly forms were simple. simple.

–– simple simple forms begatforms begat more more complex forms overcomplex forms over time time

•• AristotleAristotle (350 BC) (350 BC)

–– decayingdecaying material could be transformed by the material could be transformed by the‘‘Spontaneous Action of Nature' into living animalsSpontaneous Action of Nature' into living animals

•• ArchBishop UsherArchBishop Usher ( (earlyearly 1600 1600’’s)s) and his scholars and his scholars

–– provided exact dates for all the various occurrences in theprovided exact dates for all the various occurrences in thenew Bible being translated for King Jamesnew Bible being translated for King James

–– ‘‘provedproved’’ to the King that the world was created on to the King that the world was created onTuesday, October 8, 4004 BC at 9:30 in the morningTuesday, October 8, 4004 BC at 9:30 in the morning

Chemical EvolutionChemical EvolutionOparin Hypothesis (early 1930s)Oparin Hypothesis (early 1930s)

1) 1) Formation of the planetFormation of the planet with gases in the with gases in theatmosphere that could serve as the rawatmosphere that could serve as the rawmaterials for life.materials for life.

–– most widely accepted astronomical theory formost widely accepted astronomical theory forthe origin of the earth and the rest of the solarthe origin of the earth and the rest of the solarsystem is that the solar system formed aboutsystem is that the solar system formed about4.7 billion years ago from a diffuse dust cloud4.7 billion years ago from a diffuse dust cloud

–– central portion probably condensed to formcentral portion probably condensed to formthe sun and areas in the outer parts of thethe sun and areas in the outer parts of thecloud condensed to form the planetscloud condensed to form the planets

–– beginning of the universe according to the "Bigbeginning of the universe according to the "BigBang" theory occurred about 15 billion yearsBang" theory occurred about 15 billion yearsagoago

Chemical EvolutionChemical EvolutionOparin HypothesisOparin Hypothesis

2) 2) Random synthesis of simple organic moleculesRandom synthesis of simple organic molecules

(such as amino acids that make up proteins)(such as amino acids that make up proteins)

from the gases in the surrounding atmosphere.from the gases in the surrounding atmosphere.

3) 3) Formation of larger, more complex moleculesFormation of larger, more complex molecules

(Macromolecules) from the simple organic(Macromolecules) from the simple organic

molecules, e.g., the formation of simple proteins.molecules, e.g., the formation of simple proteins.

4) 4) Formation of coacervatesFormation of coacervates - unique droplets - unique droplets

containing the macromolecules , i.e., acontaining the macromolecules , i.e., a

coacervates consists of chemicals suspendedcoacervates consists of chemicals suspended

within a liquid surrounded by a membrane, e.g.within a liquid surrounded by a membrane, e.g.

a droplet consisting of chemicals in watera droplet consisting of chemicals in water

surrounded by an oil layer membrane.surrounded by an oil layer membrane.

Chemical EvolutionChemical EvolutionOparin HypothesisOparin Hypothesis

5) 5) Development of some type of chemical organizersDevelopment of some type of chemical organizersthat function to give these droplets the ability tothat function to give these droplets the ability totake in molecules, discharge other molecules, andtake in molecules, discharge other molecules, andcontrol and maintain a characteristic chemicalcontrol and maintain a characteristic chemicalpattern. These chemical organizers wouldpattern. These chemical organizers wouldprobably be similar to nucleic acids (that make upprobably be similar to nucleic acids (that make upchromosomes).chromosomes).

6) 6) Development of controlled reproductionDevelopment of controlled reproduction to insure to insurethat resultant daughter cells have the samethat resultant daughter cells have the samechemical capabilities. The droplets could now bechemical capabilities. The droplets could now beconsidered to be primitive cells.considered to be primitive cells.

7) 7) Beginnings of evolutionary developmentsBeginnings of evolutionary developments so that a so that agroup of cells could adapt to changes in thegroup of cells could adapt to changes in theenvironment over time.environment over time.

Miller-Urey ExperimentMiller-Urey Experiment•• conductedconducted in 1953 by Stanley Miller with Harold in 1953 by Stanley Miller with Harold

UreyUrey

•• the first experiment to about the evolution ofthe first experiment to about the evolution ofprebiotic chemicals and the origin of life onprebiotic chemicals and the origin of life onEarthEarth

–– mixture of methane, ammonia,mixture of methane, ammonia,hydrogen, and water vaporhydrogen, and water vaporintroduced into a 5-liter flaskintroduced into a 5-liter flask(simulate the Earth's primitive,(simulate the Earth's primitive,reducing atmosphere)reducing atmosphere)

–– energized by an electrical dischargeenergized by an electrical dischargeapparatus to represent ultravioletapparatus to represent ultravioletradiation from the Sunradiation from the Sun

–– products were allowed to condenseproducts were allowed to condenseand collect in a lower flask whichand collect in a lower flask which

Miller-Urey ExperimentMiller-Urey Experiment–– heat supplied to this flask recycledheat supplied to this flask recycled

the water vapor just as waterthe water vapor just as waterevaporates from lakes and seas,evaporates from lakes and seas,before moving into the atmospherebefore moving into the atmosphereand condensing again as rainand condensing again as rain

–– after a day of continuous operationafter a day of continuous operation

•• a thin layer of hydrocarbons on thea thin layer of hydrocarbons on thesurface of the watersurface of the water

–– after about a week of operationafter about a week of operation

•• a dark brown scum had collected ina dark brown scum had collected inthe lower flask and was found tothe lower flask and was found tocontain several types of aminocontain several types of aminoacids, including glycine andacids, including glycine andalanine, together with sugars, tars,alanine, together with sugars, tars,and various other unidentifiedand various other unidentifiedorganic chemicalsorganic chemicals

The Just-Right PlanetThe Just-Right PlanetRead CONNECTIONS on page 139.Read CONNECTIONS on page 139.

Evolution of First LifeEvolution of First Life•• Formation of the earliest precursors of lifeFormation of the earliest precursors of life

––must have self-organizedmust have self-organized

––acquired the capabilities needed to survive and reproduceacquired the capabilities needed to survive and reproduce

•• BiomoleculesBiomolecules of life became enclosed within a lipid of life became enclosed within a lipid

membranemembrane

––forming rudimentary assemblages that resembled cells orforming rudimentary assemblages that resembled cells or

protocellsprotocells

•• Essential Essential protocellularprotocellular functions functions

––acquisition of energy from the environmentacquisition of energy from the environment

––use of energy to synthesize molecules use of energy to synthesize molecules –– metabolismmetabolism

––information transfer to succeeding generations information transfer to succeeding generations –– geneticsgenetics

EvidenceEvidence

FossilsFossils

•• Oldest fossils are theOldest fossils are theapproximately 3.465approximately 3.465billion-year-oldbillion-year-oldmicrofossils from themicrofossils from theApexApex Chert Chert, Australia, Australia

–– colonies ofcolonies ofcyanobacteriacyanobacteria(formerly called blue-(formerly called blue-green algae) whichgreen algae) which

built real reefs built real reefs

FossilsFossils1600's - Danish scientist Nicholas Steno studied1600'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 layersformed 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 olderany 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 oneinterpretation of Earth history, because at any one

location it indicates the relative ages of rock layerslocation it indicates the relative ages of rock layers

and the fossils in them.and the fossils in them.

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

radioactive decayradioactive decay

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

radioactive decayradioactive decay

BiologicalBiological

EvolutionEvolution

(ORGANIC) EVOLUTION:(ORGANIC) EVOLUTION:

change in change in gene frequenciesgene frequencies

within populations fromwithin populations from

generation to generation.generation to generation.

(ORGANIC) EVOLUTION:(ORGANIC) EVOLUTION:

gene frequencies over timegene frequencies over time

……no concepts ofno concepts of ““planningplanning”” or or

““progressprogress”” apply. No goals! apply. No goals!

Early EvolutionistsEarly Evolutionists’’

Anthropocentric view:Anthropocentric view:

Scala Natura Scala Natura (ladder of life).(ladder of life).

A linear riseA linear rise

fromfrom

‘‘primitiveprimitive’’ to to

‘‘advancedadvanced’’..

Early EvolutionistsEarly Evolutionists’’

Anthropocentric view:Anthropocentric view:

Scala Natura Scala Natura (ladder of life).(ladder of life).

Needless to say, weNeedless to say, we

are the are the mostmost

‘‘advancedadvanced’’ in this in this

schemescheme……after all, itafter all, it’’ss

our ladderour ladder!!!!

Evolutionary BushEvolutionary Bush

One life-form splits into twoOne life-form splits into two

and those branches splitand those branches split

(independently) to make(independently) to make

more.more.

PhenotypicPhenotypic

‘‘distancedistance’’

Evolutionary Bush --Evolutionary Bush --

thousands of earlier andthousands of earlier and

later branches.later branches.

At any given moment (e.g. theAt any given moment (e.g. the

‘‘presentpresent’’), all we see is ), all we see is currentcurrent

diversitydiversity……

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

Four causes of evolutionaryFour causes of evolutionary

change:change:

1.1. MutationMutation:: fundamental origin of fundamental origin of allall genetic genetic

(DNA) change.(DNA) change.

change:change:

1.1. MutationMutation:: fundamental origin of fundamental origin of allall genetic genetic

(DNA) change.(DNA) change.

Point mutationPoint mutation

……some at base-pair levelsome at base-pair level

change:change:

1.1. MutationMutation:: fundamental origin of fundamental origin of allall

genetic (DNA) change.genetic (DNA) change.

Crossing-overCrossing-over

……others at grosserothers at grosser

chromosome levelchromosome level

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.

In a continuousIn a continuous

population, geneticpopulation, genetic

novelty can spreadnovelty can spread

locally.locally.

change:change:

2.2. Genetic DriftGenetic Drift:: isolated populations isolated populations

accumulate different mutations over time.accumulate different mutations over time.

Local spreading of allelesLocal spreading of alleles

change:change:

2.2. Genetic DriftGenetic Drift:: isolated populations isolated populations

accumulate different mutations over time.accumulate different mutations over time.

Local spreading of allelesLocal spreading of alleles

change:change:

2.2. Genetic DriftGenetic Drift:: isolated populations accumulate isolated populations accumulate

different mutations over time.different mutations over time.

Spreading processSpreading process

known as known as ‘‘genegene

flowflow’’..

change:change:

But inBut in

discontinuousdiscontinuous

populations, populations, genegene

flowflow is blocked. is blocked.

change:change:

VariationsVariations

accumulate withoutaccumulate without

inter-demicinter-demic exchange exchange

change:change:

Of course, thisOf course, this

works at manyworks at many

lociloci

simultaneouslysimultaneously

Four causes of evolutionary changeFour causes of evolutionary change

2.2. Genetic DriftGenetic Drift: isolation : isolation accumulateaccumulate

mutationsmutations

3.3. Founder EffectFounder Effect:: sampling biassampling bias during during

immigration. When a new population isimmigration. When a new population is

formed, its genetic composition dependsformed, its genetic composition depends

largely on the gene frequencies within thelargely on the gene frequencies within the

group of first settlers.group of first settlers.

Founder Effect.--Founder Effect.--

Human example: your tribe had toHuman example: your tribe had to

live near the Bering land bridgelive near the Bering land bridge……

Founder Effect.--Founder Effect.--

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

Audeskirk & Audeskirk, 1993

Galapagos FinchesGalapagos Finches

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

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

mutationsmutations

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

4.4. Natural SelectionNatural Selection: differential: differential

reproduction of individuals in the samereproduction of individuals in the same

population based on genetic differencespopulation based on genetic differences

among them.among them.

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

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

mutationsmutations

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

Evidence ofEvidence of

EvolutionEvolution

1. Biogeography:1. Biogeography:

Geographical distribution of speciesGeographical distribution of species

2. Fossil Record:2. Fossil Record:

Fossils and the order inFossils and the order in

which they appear in layers ofwhich they appear in layers of

sedimentary rock (sedimentary rock (strongeststrongest

evidenceevidence))

3. Taxonomy:3. Taxonomy:

Classification of life forms.Classification of life forms.

4. Homologous Structures:4. Homologous Structures:

Structures thatStructures that

are similarare similar

because ofbecause of

commoncommon

ancestryancestry

(comparative(comparative

anatomy)anatomy)

Turtle Alligator Bird Mammals

Typical primitive

5. Comparative Embryology: 5. Comparative Embryology:

Study ofStudy of

structuresstructures

that appearthat appear

duringduring

embryonicembryonic

developmentdevelopment

6. Molecular Biology:6. Molecular Biology:

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

History ofHistory of

Theories ofTheories of

EvolutionEvolution

Old Theories of EvolutionOld Theories of EvolutionJean Baptiste Lamarck (early 1800Jean Baptiste Lamarck (early 1800’’s)s)

proposed:proposed:

““The inheritance of acquiredThe inheritance of acquiredcharacteristicscharacteristics””

He proposed that by using or not usingHe proposed that by using or not usingits body parts, an individual tends toits body parts, an individual tends to

develop certain characteristics, which itdevelop certain characteristics, which itpasses on to its offspring.passes on to its offspring.

““The Inheritance of AcquiredThe Inheritance of Acquired

CharacteristicsCharacteristics””

•• Example:Example:

A giraffe acquired its long neckA giraffe acquired its long neck

because its ancestor stretched higherbecause its ancestor stretched higher

and higher into the trees to reachand higher into the trees to reach

leaves, and that the animalleaves, and that the animal’’ss

increasingly lengthened neck wasincreasingly lengthened neck was

passed on to its offspring.passed on to its offspring.

Charles DarwinCharles Darwin•• Darwin set sail on the H.M.S. BeagleDarwin set sail on the H.M.S. Beagle

(1831-1836) to survey the south seas(1831-1836) to survey the south seas(mainly South America and the(mainly South America and theGalapagos Islands) to collect plants andGalapagos Islands) to collect plants andanimals.animals.

•• On the Galapagos Islands, DarwinOn the Galapagos Islands, Darwinobserved species that lived no where elseobserved species that lived no where elsein the world.in the world.

•• These observations led Darwin to writeThese observations led Darwin to writea booka book

Pinta IslandIntermediate

Isabela IslandDome-shaped shell

Hood IslandSaddle-backed

shellHoodFloreana

Santa Fe

Marchena

Fernandina

Isabela

Giant Tortoises of the Giant Tortoises of the GalápagosGalápagosIslandsIslands

http://www.galapagosislands.com

Charles DarwinCharles Darwin

Wrote in 1859:Wrote in 1859:

““On the Origin of Species by Means ofOn the Origin of Species by Means ofNatural SelectionNatural Selection””

Two main conclusions:Two main conclusions:

1.1. Species were not created in theirSpecies were not created in theirpresent form, but evolved frompresent form, but evolved fromancestral species.ancestral species.

2.2. Proposed a mechanism for evolution:Proposed a mechanism for evolution:NATURAL SELECTIONNATURAL SELECTION

DarwinDarwin’’s Observationss Observations

1.1. Most species produce more offspringMost species produce more offspringthan can be supported by thethan can be supported by the

environmentenvironment

2.2. Environmental resources are limitedEnvironmental resources are limited

3.3. Most populations are stable in sizeMost populations are stable in size

4.4. Individuals vary greatly in theirIndividuals vary greatly in theircharacteristics (phenotypes)characteristics (phenotypes)

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

Natural SelectionNatural Selection

•• Individuals with favorable traits areIndividuals with favorable traits are

more likely to leave more offspringmore likely to leave more offspring

better suited for their environmentbetter suited for their environment

•• Also known as Also known as ““DifferentialDifferential

ReproductionReproduction””

Example:Example:

English pEnglish peeppppeerreedd

moth moth (Biston betularia)

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

Individuals

Size of individuals

Small Large

1.1. Stabilizing SelectionStabilizing Selection

Acts upon extremes and favorsActs upon extremes and favors

the intermediatethe intermediate

Number

Individuals

Size of individuals

Small Large

2.2. Directional SelectionDirectional Selection

Favors variants of one extremeFavors variants of one extreme

Number

Individuals

Size of individuals

Small Large

3.3. Diversifying SelectionDiversifying Selection

Favors variants of oppositeFavors variants of opposite

extremesextremes

Number

Individuals

Size of individuals

Small Large

SpeciationSpeciation

Evolution of new speciesEvolution of new species

Reproductive BarriersReproductive Barriers

Any mechanism that impedes twoAny mechanism that impedes twospecies from producing fertilespecies from producing fertileand/or viable hybrid offspring.and/or viable hybrid offspring.

Two barriers:Two barriers:

1.1. Pre-zygotic barriersPre-zygotic barriers

2.2. Post-zygotic barriersPost-zygotic barriers

1.1. Pre-zygotic BarriersPre-zygotic Barriers

a. Temporal isolation:a. Temporal isolation:

Breeding occurs at different times forBreeding occurs at different times fordifferent speciesdifferent species

b. Habitat isolation:b. Habitat isolation:

Species breed in different habitatsSpecies breed in different habitats

c. Behavioral isolation:c. Behavioral isolation:

Little or no sexual attraction betweenLittle or no sexual attraction betweenspeciesspecies

1.1. Pre-zygotic BarriersPre-zygotic Barriers

d. Mechanical isolation:d. Mechanical isolation:

Structural differences prevent gameteStructural differences prevent gamete

exchangeexchange

e. Gametic isolation:e. Gametic isolation:

Gametes die before uniting with gametesGametes die before uniting with gametes

of other species, or gametes fail to uniteof other species, or gametes fail to unite

2.2. Post-zygotic BarriersPost-zygotic Barriersa. Hybrid inviability:a. Hybrid inviability:

Hybrid zygotes fail to develop or fail toHybrid zygotes fail to develop or fail to

reach sexual maturityreach sexual maturity

b. Hybrid sterility:b. Hybrid sterility:

Hybrid fails to produce functional gametesHybrid fails to produce functional gametes

c. Hybrid breakdown:c. Hybrid breakdown:

Offspring of hybrids are weak or infertileOffspring of hybrids are weak or infertile

Evidence forEvidence for

NaturalNatural

SelectionSelection

Artificial SelectionArtificial Selection

The selective breeding ofThe selective breeding of

domesticated plants and animalsdomesticated plants and animals

by manby man

Question: WhatQuestion: What’’s the ancestor ofs the ancestor of

the domesticated dog?the domesticated dog?

Population GeneticsPopulation Genetics

The science of genetic change inThe science of genetic change in

population population –– Hardy-Weinberg Hardy-Weinberg

PopulationPopulation

A localized group of individualsA localized group of individuals

belonging to the same speciesbelonging to the same species

SpeciesSpecies

A group of populations whoseA group of populations whoseindividuals have the potential toindividuals have the potential tointerbreed and produce viableinterbreed and produce viable

offspringoffspring

Gene PoolGene PoolThe total collection of genes in aThe total collection of genes in a

population at any one timepopulation at any one time

BibliographyBibliography1. Miller 11th Edition

2. http://abandoncorporel.ca/medias/evolution.jpg

3. http://www.ne.jp/asahi/clinic/yfc/fetus.html

4. rob.ossifrage.net/images/

5. http://www.mun.ca/biology/scarr/Five_Kingdoms_Three_Domains.htm

6. http://www.gpc.peachnet.edu/~ccarter/Millerlec5/Millerlec5.PPT

7. http://www.dnr.state.md.us/education/horseshoecrab/lifecycle.html

8. http://www.falcons.co.uk/mefrg/Falco/13/Species.htm

9. http://www.sms.si.edu/irlspec/NamSpecies.htm

10. http://www.falcons.co.uk/mefrg/Falco/13/Species.htm

11. http://www.globalchange.umich.edu/globalchange1/current/lectures/complex_life/complex_life.html

12. http://nsm1.nsm.iup.edu/rwinstea/oparin.shtm

13. http://www.angelfire.com/on2/daviddarling/MillerUreyexp.htm

14. http://exobiology.nasa.gov/ssx/biomod/origin_of_life_slideshow/origin_of_life_slideshow.html

15. http://www.geo.cornell.edu/geology/classes/Geo104/HistoryofEarth.html

16. http://astrobiology.arc.nasa.gov/roadmap/objectives/o2_cellular_components.html

17. http://pubs.usgs.gov/gip/fossils/

18. http://hyperphysics.phy-astr.gsu.edu/hbase/nuclear/halfli.html

19. http://www.accessexcellence.org/AE/AEPC/WWC/1995/teach_rad.html

20. http://biology.usgs.gov/s+t/SNT/noframe/pi179.htm

21. http://www.npca.org/magazine/2001/march_april/nonnative_species.asp

22. http://www.bagheera.com/inthewild/spot_spkey.htm

23. Biology, 2003, Prentice Hall

24. http://www.nearctica.com/ecology/habitats/island.htm

25. http://www.valdosta.edu/~grissino/geog4900/lect_1.htm

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