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Chapter 16Chapter 16
Section 1: Genetic EquilibriumSection 1: Genetic Equilibrium
Variation of Traits In a Variation of Traits In a PopulationPopulation
• Population GeneticsPopulation Genetics– Microevolution vs. macroevolutionMicroevolution vs. macroevolution– Range of variations Range of variations – Bell curveBell curve
• Causes of VariationCauses of Variation– MutationMutation– RecombinationRecombination– Random fusion of gametesRandom fusion of gametes
Allele Frequencies and Gene Allele Frequencies and Gene PoolPool
• Gene poolGene pool
• Allele frequencyAllele frequency
• Phenotype frequencyPhenotype frequency
• Calculating allele frequencyCalculating allele frequency– Must add up to 1Must add up to 1– 1- freq. RR – freq. rr = freq. of Rr1- freq. RR – freq. rr = freq. of Rr
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• Maintaining Genetic Equilibrium – Maintaining Genetic Equilibrium – The Hardy-Weinberg EquilibriumThe Hardy-Weinberg Equilibrium– No mutationsNo mutations– Random matingRandom mating– Large populationLarge population– No emmigration/immigrationNo emmigration/immigration– No natural selectionNo natural selection
Genetic Equilibrium
Hardy-Weinberg Equation:Hardy-Weinberg Equation:
• p + q = 1 p + q = 1 allele frequency allele frequency•p = freq. of Ap = freq. of A
•q = freq. of aq = freq. of a
• pp22 + 2pq + q + 2pq + q22 = 1 = 1 phenotype phenotype frequencyfrequency
•pp22 = freq. of AA = freq. of AA
•qq22 = freq. of aa = freq. of aa
•2pq = freq. of Aa2pq = freq. of Aa
Chapter 16Chapter 16
Section 2: Disruption of Section 2: Disruption of Genetic EquilibriumGenetic Equilibrium
QODQOD
What disrupts genetic What disrupts genetic equilibrium?equilibrium?
Disruptions to Genetic Disruptions to Genetic EquilkibriumEquilkibrium
• MutationMutation• Gene flowGene flow
– ImmigrationImmigration– EmigrationEmigration
• Genetic driftGenetic drift• Nonrandom mating Nonrandom mating
– assortative matingassortative mating– Sexual selectionSexual selection
• Natural SelectionNatural Selection
Types of SelectionTypes of Selection
• Stabilizing selectionStabilizing selection
• Directional selectionDirectional selection
• Disruptive selectionDisruptive selection
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Stabilizing Selection
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Directional Selection
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Disruptive Selection
QODQOD
What is speciation? How does What is speciation? How does it happen?it happen?
Chapter 16Chapter 16
Section 3: Formation of Section 3: Formation of SpeciesSpecies
The Concept of a SpeciesThe Concept of a Species
• SpeciationSpeciation
• Morphological Concept of SpeciesMorphological Concept of Species– Morphology and classificationMorphology and classification– LimitationsLimitations
• Biological Species ConceptBiological Species Concept– FertilityFertility– LimitationsLimitations
Requirements for SpeciationRequirements for Speciation
• IsolationIsolation– Gene flowGene flow
• Natural selection and genetic driftNatural selection and genetic drift
• Diverge into two distinct speciesDiverge into two distinct species
Isolating MechanismsIsolating Mechanisms
• Geographic isolationGeographic isolation– Allopatric speciationAllopatric speciation
• Reproductive isolationReproductive isolation– PrezygoticPrezygotic– PostzygoticPostzygotic
• Sympatric speciationSympatric speciation
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Geographic Isolation
Speciation RatesSpeciation Rates
• GradualismGradualism
• Punctuated Punctuated equilibriumequilibrium