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### Transcript of Hardy Weinberg Populations

• 1.Measuring Evolution of Populations

2. 5 Agents of evolutionary change Mutation Gene Flow Genetic Drift Selection Non-random mating 3. Populations & gene pools

• Concepts
• apopulationis a localized group of interbreeding individuals
• gene pooliscollection of allelesin the population
• remember difference betweenalleles(gene variations) &genes !
• allele frequency is how common that allele is within the population
• how manyAsvs.asin whole population

4. Evolution of populations

• Evolution =change in allele frequenciesin a population
• hypothetical : what conditions would cause allele frequencies tonotchange?
• non-evolving population
• REMOVEall agents of evolutionary change
• very large population size (nogenetic drift )
• no migration (nogene flowin or out)
• nomutation(no genetic change)
• random mating(no sexual selection)
• nonatural selection(everyone is equally fit)

5. Hardy-Weinberg equilibrium

• Hypothetical, non-evolving population
• preserves allele frequencies
• Serves as a model
• natural populations rarely inH-W equilibrium
• useful model tomeasureif forces are
• acting on a population
• measuring evolutionary change

W. Weinberg physician G.H. Hardy mathematician 6. Hardy-Weinberg theorem

• CountingAlleles
• assume 2 alleles =B ,b
• frequencyof dominant allele ( B ) = p
• frequencyof recessive allele ( b ) =q
• frequencies must add to 1 (100%), so:
• p+q= 1

bb Bb BB 7. Hardy-Weinberg theorem

• CountingIndividuals
• frequency ofhomozygous dominant :pxp=p 2
• frequency ofhomozygous recessive : qxq=q 2
• frequency ofheterozygotes :( pxq ) + ( qxp ) =2p q
• frequencies ofall individualsmust add to 1 (100%), so:
• p 2+ 2pq +q 2= 1

bb Bb BB 8. H-W formulas

• Alleles: p +q = 1
• Individuals: p 2+ 2p q + q 2= 1

bb Bb BB BB B b Bb bB bb 9. Using Hardy-Weinberg equation What are the genotype frequencies? q 2(bb): 16/100 = .16 q(b): .16 =0.4 p(B): 1 - 0.4 =0.6 population:100 cats 84 black, 16 white How many of each genotype? bb Bb BB p 2 =.36 2pq =.48 q 2 =.16 Must assume population is in H-W equilibrium! 10. Any Questions?? Any Questions?? Any Questions??