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
No selectionNo selection
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
Range of values for the trait at time 2
Range of values for the trait at time 3
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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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Range of values for the trait at time 1
Range of values for the trait at time 2
Range of values for the trait at time 3
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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Range of values for the trait at time 1
Range of values for the trait at time 2
Range of values for the trait at time 3
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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
No selectionNo selection
No selectionNo selection
No selectionNo selection
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
branch point (a time of divergence, speciation)
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
branch point (a time of divergence, speciation)
a single lineage
branch point (a time of divergence, speciation)
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
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