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