Lecture 9 Evolution: Lecture 9 Evolution: Now Playing: Snog “The Human Germ”

Lecture 9

Evolution:

Lecture 9

Evolution:

Now Playing:Snog

“The Human Germ”

Goals:Goals:1. Define truth, geological record, phylogeny, cladistics 1. Define truth, geological record, phylogeny, cladistics

2. Review naïve inductivism, understand concepts of truth, materialism, naturalism, replication, saltation,

punctuated equilibrium, missing links, thermodynamics, speciation, predictability, natural selection, chance

2. Review naïve inductivism, understand concepts of truth, materialism, naturalism, replication, saltation,

punctuated equilibrium, missing links, thermodynamics, speciation, predictability, natural selection, chance

3. Relate topics to life, science, health and agriculture 3. Relate topics to life, science, health and agriculture Assignment:Assignment:

Read: Chapter 16, 17, 18Read: Chapter 16, 17, 18Websites: http://www.religioustolerance.org/abs_true.htm http://earth.ics.uci.edu/http://www.cs.colorado.edu/~lindsay/creation/index.htmlhttp://lrc.geo.umn.edu/people/teed/papers/macroev.htmlhttp://www.intellectualcapital.com/issues/issue178/item1315.asphttp://www.religioustolerance.org/evolutio.htmhttp://www.mun.ca/biology/scarr/3900_Fossils.htmhttp://www.fossilnews.com/1996/cladistics.html

ReproductionReproduction

VariationVariation

SurvivalSurvival

SelectionSelection

Microevolution Vs Macroevolution: Definitions

Microevolution Vs Macroevolution: Definitions

Mechanism of Mechanism of EvolutionEvolutionMechanism of Mechanism of EvolutionEvolution VariationVariation

– Mutations- new Mutations- new allelesalleles

– Natural SelectionNatural Selection– Genetic DriftGenetic Drift– Gene FlowGene Flow

SelectionSelection– Directional SelectionDirectional Selection– Stabilizing SelectionStabilizing Selection– Disruptive SelectionDisruptive Selection

VariationVariation– Mutations- new Mutations- new

allelesalleles– Natural SelectionNatural Selection– Genetic DriftGenetic Drift– Gene FlowGene Flow

SelectionSelection– Directional SelectionDirectional Selection– Stabilizing SelectionStabilizing Selection– Disruptive SelectionDisruptive Selection

SurvivalSurvival– Selective forcesSelective forces

Abiotic- weather, Abiotic- weather, naturenature

Biotic- diseasesBiotic- diseases

CompetitionCompetition

ReproductionReproduction– Advantageous traits Advantageous traits

must be passed to must be passed to progenyprogeny

– Ability to pass on the Ability to pass on the genotype to the next genotype to the next generation is the generation is the measure of successmeasure of success

SurvivalSurvival– Selective forcesSelective forces

Abiotic- weather, Abiotic- weather, naturenature

Biotic- diseasesBiotic- diseases

CompetitionCompetition

ReproductionReproduction– Advantageous traits Advantageous traits

must be passed to must be passed to progenyprogeny

– Ability to pass on the Ability to pass on the genotype to the next genotype to the next generation is the generation is the measure of successmeasure of success

Biological Change Over Biological Change Over TimeTime

MicroevolutionMicroevolutionChanges with in Changes with in speciesspecies

Well defined Well defined mechanismmechanism

Easily observedEasily observedBased on Based on selectionselection

MacroevolutionMacroevolutionChange from one Change from one species to anotherspecies to another

Undefined Undefined mechanismmechanism

Interpretation of:Interpretation of:– CladisticsCladistics– Fossil recordFossil record– Geological dataGeological data

Microevolutionary Microevolutionary ProcessesProcesses

Drive a population away from Drive a population away from genetic equilibriumgenetic equilibrium

Small-scale changes in allele Small-scale changes in allele frequencies brought about by:frequencies brought about by:– Natural selectionNatural selection

– Gene flowGene flow

– Genetic driftGenetic drift

MicroevolutionMicroevolutionGeneticsGenetics Microevolution Microevolution

changes a population changes a population not individualsnot individuals

Traits in a population Traits in a population vary among vary among individualsindividuals

Microevolution is Microevolution is change in frequency change in frequency of traitsof traits

Natural SelectionNatural Selection Reproductive success Reproductive success

for winning for winning phenotypesphenotypes

Acts directly on Acts directly on phenotypes and phenotypes and indirectly on indirectly on genotypesgenotypes

The first changed The first changed individual has no individual has no advantageadvantage

The Gene PoolThe Gene Pool All of the genes in the All of the genes in the

population population Genetic resource that Genetic resource that

is shared (in theory) is shared (in theory) by all members of by all members of populationpopulation

Phenotype VariationPhenotype Variation Two copies of each gene (2 Two copies of each gene (2

alleles)alleles) Inherit different allele Inherit different allele

combinationscombinations Different combinations= Different combinations=

different phenotypesdifferent phenotypes Inherit genotype, NOT Inherit genotype, NOT

phenotypesphenotypes Variation is inheritedVariation is inherited

Fig. 10.18, p. 166

Genotypes, Phenotypes Genotypes, Phenotypes and Environmental Effectsand Environmental Effects

Himalayan rabbit experimentHimalayan rabbit experiment1.1. Pluck harePluck hare

2.2. Grow hair with cold packGrow hair with cold pack

Rabbits share genotype but phenotype Rabbits share genotype but phenotype is dependent on environmental is dependent on environmental conditionsconditions

Genetic EquilibriumGenetic Equilibrium Allele frequencies at a locus are not Allele frequencies at a locus are not

changingchanging 5 Rules for Equilibrium5 Rules for Equilibrium1.1. No mutationNo mutation

2.2. No immigration/ No immigration/

emigrationemigration

3.3. Gene doesn’t affect Gene doesn’t affect

survival or reproductionsurvival or reproduction

4.4. Large populationLarge population

5.5. Random matingRandom mating

InterpreteInterprete

ddNo VariationNo Variation

No VariationNo Variation

No selectionNo selection



What happens when What happens when the rules are broken?the rules are broken?

Rule #1 Rule #1 No MutationNo Mutation

Biological information changesBiological information changes Each gene has own mutation Each gene has own mutation

raterate– What determines rates?What determines rates?

Effect of mutations on selectionEffect of mutations on selection– LethalLethal– Neutral Neutral – Advantageous Advantageous

Variation in the gene Variation in the gene pool? pool? 1.1. RecombinationRecombination

• Crossing over at meiosis ICrossing over at meiosis I

2.2. Independent assortmentIndependent assortment• Meiosis II (haploid germ cells)Meiosis II (haploid germ cells)

3.3. FertilizationFertilization• Haploid + haploid = diploidHaploid + haploid = diploid

4.4. Changes in chromosome Changes in chromosome number or structurenumber or structure

5.5. Mutations Mutations

Reorganizing Information

Changing Information

VariationVariation

Mountain bluebirdMountain bluebirdWestern

bluebird

Western

bluebird

Eastern bluebirdEastern bluebird

Rule #2 No Rule #2 No ImmigrationImmigration Immigration from a separate, Immigration from a separate,

segregated populationssegregated populations– New variationNew variation

AllelesAlleles MutationsMutations

Effects of immigrationEffects of immigration– Shifts allele frequencyShifts allele frequency– Introduces new mutations through Introduces new mutations through

breedingbreeding

Gene FlowGene Flow

Physical flow of alleles into a Physical flow of alleles into a populationpopulation

Tends to keep the gene pools of Tends to keep the gene pools of populations similarpopulations similar

Counters the differences Counters the differences between two populations that between two populations that result from mutation, natural result from mutation, natural selection, and genetic driftselection, and genetic drift

Rule #3 Rule #3 Survival or Survival or Reproductive Reproductive AdvantageAdvantageWhat does selection do for a What does selection do for a

population?population?

Survival advantage or Survival advantage or Reproductive advantageReproductive advantage

Pillars of Natural Pillars of Natural SelectionSelectionPillars of Natural Pillars of Natural SelectionSelection

1.1. Individuals of all populations have the capacity to produce Individuals of all populations have the capacity to produce more offspring than the environment is able to support, so more offspring than the environment is able to support, so individuals must compete for resources.individuals must compete for resources.

2.2. Individuals of a population vary in size, form, and other Individuals of a population vary in size, form, and other traits. The variant forms of a trait may be more or less traits. The variant forms of a trait may be more or less adaptive under prevailing conditions.adaptive under prevailing conditions.

3.3. When a form of a trait is adaptive under prevailing When a form of a trait is adaptive under prevailing conditions, and when it has a heritable basis, its bearers conditions, and when it has a heritable basis, its bearers tend to survive and reproduce more frequently than tend to survive and reproduce more frequently than individuals with less adaptive forms of the trait. Over individuals with less adaptive forms of the trait. Over generations, the adaptive version becomes more common in generations, the adaptive version becomes more common in the population.the population.

4.4. Natural selection is the result of differences in survival and Natural selection is the result of differences in survival and reproduction among individuals of a population that differ reproduction among individuals of a population that differ from one another in one or more traits.from one another in one or more traits.

5.5. Natural selection results in modifications of traits within a Natural selection results in modifications of traits within a line of descent. Over time, it may bring about the evolution line of descent. Over time, it may bring about the evolution of a new species, with an array of traits uniquely its own.of a new species, with an array of traits uniquely its own.

Basics of Natural Basics of Natural SelectionSelectionCapacity and CompetitionCapacity and Competition

All populations have the capacity All populations have the capacity to increase in numbersto increase in numbers

No population can increase No population can increase indefinitelyindefinitely

Eventually, the individuals of a Eventually, the individuals of a population will end up competing population will end up competing for resourcesfor resources

Basics of Natural Basics of Natural SelectionSelectionCapacity and CompetitionCapacity and Competition

The alleles that produce the most The alleles that produce the most successful phenotypes will successful phenotypes will increase in the populationincrease in the population

Less successful alleles will Less successful alleles will become less commonbecome less common

Change leads to increased fitnessChange leads to increased fitness– Increased adaptation to a specific Increased adaptation to a specific

environmentenvironment

Results of Natural Results of Natural SelectionSelection

Three possible outcomes:Three possible outcomes: Directional selectionDirectional selection

– Decreases variation in favor of an extreme.Decreases variation in favor of an extreme. Stabilizing selectionStabilizing selection

– Selects most average/ common form of a Selects most average/ common form of a traittrait

Disruptive selectionDisruptive selection– Selects against intermediate formsSelects against intermediate forms

Directional Directional SelectionSelection

Allele Allele frequencies frequencies shift in one shift in one directiondirection

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Range of values for the trait at time 1



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•change in the base pair sequence of DNA or RNA

•A gene frequency within a population or a species

•allelic effects on the form, or phenotype, of organisms that make up that population or species.

•change in the base pair sequence of DNA or RNA

•A gene frequency within a population or a species

•allelic effects on the form, or phenotype, of organisms that make up that population or species.

Microevolution:Microevolution:

Any change below the level of species:Any change below the level of species:

Industrial MelanismIndustrial Melanism

Stabilizing Stabilizing SelectionSelection Intermediate Intermediate

forms are forms are favored and favored and extremes are extremes are eliminatedeliminated

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ResistanceResistance

Antibiotic Antibiotic ResistanceResistance

BacteriaBacteria

Antiviral ResistanceAntiviral Resistance

HIVHIV

Pesticide Pesticide ResistanceResistance

InsectsInsects

Chemical kills Chemical kills susceptible susceptible individualsindividuals

Resistant individuals Resistant individuals survivesurvive

If resistance is If resistance is heritable, following heritable, following generations generations exhibit the same exhibit the same trait.trait.

Evolution in ActionThe DDT Paradigm

Example: Pesticide Example: Pesticide ResistanceResistanceExample: Pesticide Example: Pesticide ResistanceResistance

Pre-adapted to

survive

Pre-adapted to

survive

99% Non-resistant die99% Non-resistant die

100% resistant survive100% resistant survive

Spray PesticideSpray Pesticide

Second generationSecond generation

Second generation

survivors

Second generation

survivors

Spray with an

Insecticide

Spray with an

Insecticide

Third generationThird generation

Third generation

survivors

Third generation

survivors

Spray with an

Insecticide

Spray with an

Insecticide

100 butterflies100 butterflies

Mutation rate = 1 x 10-4

or 1 in 10,000

Mutation rate = 1 x 10-4

or 1 in 10,000

1 million butterflies1 million butterflies

Beneficial mutation = 1 x 10-9 or 1 in

1,000,000,000

Beneficial mutation = 1 x 10-9 or 1 in

1,000,000,000

Breeding “super-bugs” in the home?

Breeding “super-bugs” in the home?

Insects Evolve at a High Insects Evolve at a High RateRateInsects Evolve at a High Insects Evolve at a High RateRate

-Antibiotic resistance

-Food safety

-Bioterrorism

-GMO foods

-Antibiotic resistance

-Food safety

-Bioterrorism

-GMO foods

Disruptive Disruptive SelectionSelection

Forms at both Forms at both ends of the ends of the range of range of variation are variation are favored favored

Intermediate Intermediate forms are forms are selected selected againstagainst

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Balanced Balanced PolymorphismPolymorphism

Polymorphism - “having Polymorphism - “having many forms”many forms”

Occurs when two or more Occurs when two or more alleles are maintained at alleles are maintained at frequencies greater than 1 frequencies greater than 1 percentpercent

Sexual SelectionSexual Selection

Selection favors certain Selection favors certain secondary sexual characteristicssecondary sexual characteristics

Through nonrandom mating, Through nonrandom mating, alleles for preferred traits alleles for preferred traits increaseincrease

Leads to increased sexual Leads to increased sexual dimorphismdimorphism

Sickle-Cell Trait: Sickle-Cell Trait: Heterozygote Heterozygote AdvantageAdvantage

Allele Allele HbHbSS causes causes sickle-cell anemia sickle-cell anemia when heterozygous when heterozygous

Heterozygotes are Heterozygotes are more resistant to more resistant to malaria than malaria than homozygoteshomozygotes

less than 1 in 1,600

1 in 400-1,600

1 in 180-400

1 in 100-180

1 in 64-100

more than 1 in 64

Malaria case

Sickle cell trait

Rule #4 Large Rule #4 Large PopulationPopulation

What happens if the population or What happens if the population or allele frequency gets wacked?allele frequency gets wacked?

Genetic DriftGenetic Drift

Random change in allele frequencies Random change in allele frequencies Most pronounced in small Most pronounced in small

populationspopulations Sampling error - Fewer times an Sampling error - Fewer times an

event occurs, greater the variance in event occurs, greater the variance in outcomeoutcome

Fixation: one allele is established in a Fixation: one allele is established in a populationpopulation

Founder EffectFounder Effect Small number of Small number of

individuals start a individuals start a new populationnew population

Low probability that Low probability that allele frequencies allele frequencies are the same as are the same as original populationoriginal population

Effect is pronounced Effect is pronounced on isolated islandson isolated islands

BottleneckBottleneck A severe reduction A severe reduction

in population sizein population size Causes pronounced Causes pronounced

driftdrift ResultsResults

– All progeny will be All progeny will be very similar.very similar.

– Gene pool very Gene pool very shallowshallow

Rule #5 Random Rule #5 Random MatingMating

Inbreeding Inbreeding

Nonrandom mating between Nonrandom mating between related individualsrelated individuals

Leads to increased homozygosityLeads to increased homozygosity Can lower fitness when Can lower fitness when

deleterious recessive alleles are deleterious recessive alleles are expressedexpressed

Genetic EquilibriumGenetic Equilibrium Allele frequencies at a locus are not Allele frequencies at a locus are not

changingchanging 5 Rules for Equilibrium5 Rules for Equilibrium1.1. No mutationNo mutation

2.2. No immigration/ No immigration/

emigrationemigration

3.3. Gene doesn’t affect Gene doesn’t affect

survival or reproductionsurvival or reproduction

4.4. Large populationLarge population

5.5. Random matingRandom mating

InterpreteInterprete

ddNo VariationNo Variation

No VariationNo Variation




Macroevolution and Macroevolution and SpeciationSpeciation1.1. Biological evolution is the theory that all Biological evolution is the theory that all

living things are modified descendants of living things are modified descendants of a common ancestor that lived in the a common ancestor that lived in the distant past, or “descent with distant past, or “descent with modification.”modification.”

2.2. Evolution simply means change over time.Evolution simply means change over time.Descent with modification occurs because Descent with modification occurs because all organisms within a single species are all organisms within a single species are related through descent with modificationrelated through descent with modification

Biological Species Biological Species ConceptConcept

“ “Species are groups of interbreeding Species are groups of interbreeding natural populations that are natural populations that are reproductively isolatedreproductively isolated from other from other such groups.”such groups.”

Ernst Ernst MayrMayr

Morphology & SpeciesMorphology & Species

Morphological traits may not be Morphological traits may not be useful in distinguishing speciesuseful in distinguishing species– Members of same species may appear Members of same species may appear

different because of environmental different because of environmental conditionsconditions

– Morphology can vary with age and sexMorphology can vary with age and sex– Different species can appear identicalDifferent species can appear identical

Variable Variable MorphologyMorphology

Grown in water Grown on land

Isolation and Isolation and DivergenceDivergence

Reproductive Reproductive IsolationIsolation

Cornerstone of the Cornerstone of the biological species conceptbiological species concept

Speciation is the Speciation is the attainment of attainment of reproductive isolationreproductive isolation

Reproductive isolation Reproductive isolation arises as a arises as a by-product of genetic by-product of genetic changechange

Genetic DivergenceGenetic Divergence Gradual accumulation of Gradual accumulation of

differences in the gene differences in the gene pools of populationspools of populations

Natural selection, genetic Natural selection, genetic drift, and mutation can drift, and mutation can contribute to divergencecontribute to divergence

Gene flow counters Gene flow counters divergencedivergence

Reproductive IsolationReproductive IsolationCan’t allow gene flowCan’t allow gene flow

Prezygotic Prezygotic IsolationIsolation Ecological IsolationEcological Isolation Temporal IsolationTemporal Isolation Behavioral IsolationBehavioral Isolation Mechanical Isolation Mechanical Isolation Gametic MortalityGametic Mortality

PostzygoticPostzygotic Isolation Isolation Zygotic mortalityZygotic mortality Hybrid inviabilityHybrid inviability Hybrid sterilityHybrid sterility

Zygote is a fertilized egg

SpeciationSpeciation

AllopatricAllopatric

Different lands, (physical barrier)Different lands, (physical barrier)

Sympatric Sympatric

Same lands (no physical or ecological Same lands (no physical or ecological barrierbarrier

ParapatricParapatric

Same border (small hybrid zone)Same border (small hybrid zone)

Allopatric EffectAllopatric Effect

Speciation in geographically isolated Speciation in geographically isolated

populations populations

Probably most common mechanismProbably most common mechanism

Some sort of barrier arises and Some sort of barrier arises and

prevents gene flowprevents gene flow

Effectiveness of barrier varies with Effectiveness of barrier varies with

speciesspecies

Extensive Divergence Extensive Divergence Prevents InbreedingPrevents Inbreeding

Species separated by geographic Species separated by geographic barriers will diverge geneticallybarriers will diverge genetically

If divergence is great enough it will If divergence is great enough it will prevent inbreeding even if the prevent inbreeding even if the barrier later disappears barrier later disappears

Hawaiian IslandsHawaiian Islands

Volcanic origins, variety of habitats Volcanic origins, variety of habitats

Adaptive radiations:Adaptive radiations:– Honeycreepers - In absence of other Honeycreepers - In absence of other

bird species, they radiated to fill bird species, they radiated to fill

numerous nichesnumerous niches

– Fruit flies (Fruit flies (DrosophilaDrosophila) - 40% of fruit ) - 40% of fruit

fly species are found in Hawaiifly species are found in Hawaii

Hawaiian Hawaiian HoneycreepersHoneycreepers

FOUNDER SPECIES

Reproductive IsolationReproductive IsolationCan’t allow gene flowCan’t allow gene flow

Prezygotic Prezygotic IsolationIsolation Ecological IsolationEcological Isolation Temporal IsolationTemporal Isolation Behavioral IsolationBehavioral Isolation Mechanical Isolation Mechanical Isolation Gametic MortalityGametic Mortality

PostzygoticPostzygotic Isolation Isolation Zygotic mortalityZygotic mortality Hybrid inviabilityHybrid inviability Hybrid sterilityHybrid sterility

Zygote is a fertilized egg

Speciation without a Speciation without a BarrierBarrier

Sympatric speciationSympatric speciation

– Species forms within the home range Species forms within the home range

of the parent speciesof the parent species

Parapatric speciationParapatric speciation

– Neighboring populations become Neighboring populations become

distinct species while maintaining distinct species while maintaining

contact along a common bordercontact along a common border

Speciation by Speciation by PolyploidyPolyploidy

Change in chromosome number Change in chromosome number (3(3nn, 4, 4nn, etc.), etc.)

Offspring with altered chromosome Offspring with altered chromosome number cannot breed with parent number cannot breed with parent populationpopulation

Common mechanism of speciation in Common mechanism of speciation in flowering plantsflowering plants

Possible Evolution of Possible Evolution of WheatWheat

Triticum monococcum (einkorn)

T. aestivum (one of the common bread wheats)

Unknown species of wild wheat

T. turgidum(wild emmer)

T. tauschii (a wild relative)

42AABBDD14AA 14BB 14AB 28AABB 14DDXX

CROSS-FERTILIZATION, FOLLOWED BY A SPONTANEOUS CHROMOSOME

DOUBLING

Parapatric SpeciationParapatric Speciation

Adjacent Adjacent populations populations evolve into evolve into

distinct species distinct species while while

maintaining maintaining contact along a contact along a

common common borderborder

BULLOCK’S ORIOLE

BALTIMORE ORIOLE

HYBRID ZONE

Are We All Related?Are We All Related?

Are all species are related by Are all species are related by descent?descent?

Do we share genetic connections Do we share genetic connections that extend back in time to the that extend back in time to the first prototypical cell?first prototypical cell?

Patterns of Change Patterns of Change in a Lineagein a Lineage

CladogenesisCladogenesis– Branching patternBranching pattern– Lineage splits, isolated populations Lineage splits, isolated populations

divergediverge– Homology and morphologyHomology and morphology

AnagenesisAnagenesis– No branchingNo branching– Changes occur within single lineageChanges occur within single lineage– Gene flow throughout processGene flow throughout process

Evolutionary TreesEvolutionary Trees

new species

branch point (a time of divergence, speciation)

a single lineage


a new species

a single lineage

extinction (branch ended before present)

dashed line (only sketchy evidence of presumed evolutionary relationship)

Gradual ModelGradual Model

Speciation model in which species Speciation model in which species emerge through many small emerge through many small morphological changes that morphological changes that accumulate over a long time accumulate over a long time periodperiod

Fits well with evidence from Fits well with evidence from certain lineages in fossil recordcertain lineages in fossil record

Punctuation ModelPunctuation Model

Speciation model in which most Speciation model in which most changes in morphology are changes in morphology are compressed into brief period compressed into brief period near onset of divergence near onset of divergence

Supported by fossil evidence in Supported by fossil evidence in some lineagessome lineages

Adaptive RadiationAdaptive Radiation

Burst of divergence Burst of divergence Single lineage gives rise to Single lineage gives rise to

many new speciesmany new species New species fill vacant New species fill vacant

adaptive zone adaptive zone Adaptive zone is “way of Adaptive zone is “way of

life”life”

Adaptive RadiationAdaptive Radiation

ExtinctionExtinction

Irrevocable loss of a speciesIrrevocable loss of a species Mass extinctions have played a Mass extinctions have played a

major role in evolutionary major role in evolutionary historyhistory

Fossil record shows 20 or more Fossil record shows 20 or more large-scale extinctionslarge-scale extinctions

Reduced diversity is followed by Reduced diversity is followed by adaptive radiationadaptive radiation

Who Survives?Who Survives?

Species survival is to some extent Species survival is to some extent randomrandom

Asteroids have repeatedly struck Asteroids have repeatedly struck Earth destroying many lineagesEarth destroying many lineages

Changes in global temperature Changes in global temperature favor lineages that are widely favor lineages that are widely distributeddistributed

Fig. 17.11 p. 268

new species


a single lineage


a new species

a single lineage

extinction (branch ended before present)

dashed line (only sketchy evidence of presumed evolutionary relationship)

Fig. 17.12 p. 269

Mechanism of Mechanism of EvolutionEvolutionMechanism of Mechanism of EvolutionEvolution

Genetic VariabilityGenetic

Variability

SelectionSelectionParental

GenerationParental

Generation

ProgenyLarge PopulationsGenetic Variability

ProgenyLarge PopulationsGenetic Variability

Mechanism of Mechanism of EvolutionEvolution

Factors that cause Factors that cause changechangeFactors that cause Factors that cause changechange Mutations- new allelesMutations- new alleles Genetic Drift- unselected random Genetic Drift- unselected random

change in allele frequencieschange in allele frequencies– Genetic BottlenecksGenetic Bottlenecks

Founder effectFounder effect InbreedingInbreeding

Gene Flow- moving alleles with Gene Flow- moving alleles with matingmating

Natural SelectionNatural Selection

Mutations- new allelesMutations- new alleles Genetic Drift- unselected random Genetic Drift- unselected random

change in allele frequencieschange in allele frequencies– Genetic BottlenecksGenetic Bottlenecks

Founder effectFounder effect InbreedingInbreeding

Gene Flow- moving alleles with Gene Flow- moving alleles with matingmating

Natural SelectionNatural SelectionEvolution changes allele frequencies in populations not individuals

Struggle for survival:Struggle for survival:

Endangered species - are they less fit?Endangered species - are they less fit?

Different genetic makeup = different advantagesDifferent genetic makeup = different advantages

Fitness = ability to pass on genotype to next generation = measure of success

Fitness = ability to pass on genotype to next generation = measure of success

Survival: Selective forcesSurvival: Selective forces

Ability to adapt to human-derived habitatsAbility to adapt to human-derived habitats

- Biotic forces: Disease- Biotic forces: Disease

- Abiotic forces eg. weather- Abiotic forces eg. weather

- Competition for niches environment- Competition for niches environment

Survival of the fittest:Survival of the fittest:

Compete against

siblings and others for

food, mates, living space

Compete against

siblings and others for

food, mates, living space

Interplay of genetic variation vs selective forcesInterplay of genetic variation vs selective forces

Death before ReproductionDeath before Reproduction

Survival: Natural SelectionSurvival: Natural Selection

“Weeding out the slow and weak”“Weeding out the slow and weak”

Result of evolutionary forces --animals capable of adapting (passing on their

genes to the next generation)

Result of evolutionary forces --animals capable of adapting (passing on their

genes to the next generation)

Survival: PreadaptationSurvival: Preadaptation

Already adapted to a condition not previously

confronted with

Already adapted to a condition not previously

confronted witheg. coevolution of plants and arthropodseg. coevolution of plants and arthropods

ReproductionReproduction

Reproduction must outweigh mortalityReproduction must outweigh mortality

-Predation-Predation

-Parasitization-Parasitization

-Disease-Disease

-Lack of food-Lack of food

-Lack of nesting sites-Lack of nesting sites

-Environmental extremes-Environmental extremes

Over-reproductionOver-reproduction

Therefore...Evolution as a Scientific Theory is Well Supported by good science.Therefore...Evolution as a Scientific Theory is Well Supported by good science.

- Adequately explains:- Adequately explains:• Subspecies Groups: Races, Biotypes, etc. • Subspecies Groups: Races, Biotypes, etc.

• Resistance• Resistance

• Adaptation within species• Adaptation within species

• Domestication of Animals, microbes and plants

• Domestication of Animals, microbes and plants

Evolution is a change from a no-howish untalkaboutable all-alikeness by continuous

sticktogetherations and somethinglelsifications.

--William James (1842-1910)American Psychologist

Evolution is a change from a no-howish untalkaboutable all-alikeness by continuous

sticktogetherations and somethinglelsifications.

--William James (1842-1910)American Psychologist

Residues: Only a tiny portion of any pesticide application will contact the target organism. The rest is often carried by water, wind and soil to non-target areas and organisms, affecting the health of human and wildlife populations.

Residues: Only a tiny portion of any pesticide application will contact the target organism. The rest is often carried by water, wind and soil to non-target areas and organisms, affecting the health of human and wildlife populations.

Resistance: Pesticide use is a powerful selection pressure for changing the genetic make-up of a pest population. In the last decade, the number of weed species known to be resistant to herbicides rose from 48 to 270, and the number of plant pathogens resistant to fungicides grew from 100 to 150. Resistance to insecticides is very common. You can find the latest count on my website at http://whalonlab.msu.edu/resistance/rmdb.

Resistance: Pesticide use is a powerful selection pressure for changing the genetic make-up of a pest population. In the last decade, the number of weed species known to be resistant to herbicides rose from 48 to 270, and the number of plant pathogens resistant to fungicides grew from 100 to 150. Resistance to insecticides is very common. You can find the latest count on my website at http://whalonlab.msu.edu/resistance/rmdb.

Resurgence: Pesticides often kill off natural enemies along with the pest. Without them, resistant populations experience unchecked growthResurgence: Pesticides often kill off natural enemies along with the pest. Without them, resistant populations experience unchecked growth

Secondary Pests: Some potential pests which are normally kept to reasonable numbers by natural enemies become actual pests after their natural enemies are destroyed by pesticides. Mite outbreaks after pesticide applications are a classic example of this.

Secondary Pests: Some potential pests which are normally kept to reasonable numbers by natural enemies become actual pests after their natural enemies are destroyed by pesticides. Mite outbreaks after pesticide applications are a classic example of this.

Glossary: Chapters 16, 17, 18 & 19 each have a glossary. In addition, the terms

below will be helpful.

Glossary: Chapters 16, 17, 18 & 19 each have a glossary. In addition, the terms

below will be helpful.

Variation from Sexual Recombination:Variation from Sexual Recombination:

-Diploidy-Diploidy

-Mutation = changes in genetic sequence or chromosomal aberrations

-Mutation = changes in genetic sequence or chromosomal aberrations

-Recruitment, genetic drift = migration-Recruitment, genetic drift = migration

Lecture 9 Evolution: Lecture 9 Evolution: Now Playing: Snog “The Human Germ”

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