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Evolution within a Population Hardy-Weinberg Equilibrium

Evolution within a Population Hardy-Weinberg Equilibrium. What is a Population?. A _____________________________________________________________________________________ Individuals must be of the same species in order to mate. A Defintion.

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Evolution within a Population Hardy-Weinberg Equilibrium

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  1. Evolution within a PopulationHardy-Weinberg Equilibrium

  2. What is a Population? • A _____________________________________________________________________________________ • Individuals must be of the same species in order to mate

  3. A Defintion • Gene pool: _______________________________________________________________ ___ is always equal to the _________________________ ___ is always equal to the _________________________ 1. If you have a population of fruit files 25 are BB 70 are Bb 5 are bb What are the allele frequencies for each allele?

  4. Hardy-Weinberg Principle • Used to determine ________________________________________________________________ • States that _____________________________________________________________________________________________________ • If this is true the gene pool is said to be at _________________________________

  5. Conditions for Hardy Weinberg Equilibrium • _____________________ • No changes in genes • _____________________ • Mating is random • _________________________: • No difference in the reproductive success or survival of individuals having a different genotype • _______________________________ • _____________________ • No moving of individuals in and out of the population DEPARTURE FROM THESE CONDITIONS USUALLY LEADS TO EVOLUTIONARY CHANGE AND AS A RESULT LACK OF HARDY-WEINBERG EQUILBRUIM

  6. The Hardy Weinberg Equaltion p2 + 2pq + q2 When at equilibrium: p = ______________________________ q= ________________________________ p2 = expected frequency of _______________________________ 2pq= expected ________________________________________ q2 = expected __________________________________________ Also NOTE: p + q must equal 1

  7. Keys to Problems Where Hardy Weinberg Equilibrium is assumed • Try to calculate the percentage of recessive or dominant individuals from information given in the problem and convert to decimal • From that calculate p and q • If number heterozygous individuals are use that information to calculate the frequency of recessive alleles

  8. PRACTICE You have sampled a population in which you know that the percentage of the homozygous recessive genotype (aa) is 36%. Using that 36%, calculate the following: • The frequency of the "aa" genotype. • The frequency of the "a" allele. • The frequency of the "A" allele. • The frequencies of the genotypes "AA" and "Aa."

  9. Practice Makes Perfect • This is a classic data set on wing coloration in the scarlet tiger moth (Panaxia dominula). Coloration in this species had been previously shown to behave as a single-locus, two-allele system with incomplete dominance. Data for 1612 individuals are given below: • White-spotted (AA) =1469 Intermediate (Aa) = 138 Little spotting (aa) =5 • Calculate the following frequencies: A = a = (¦)AA = (¦)Aa = (¦)aa =

  10. More Practice PKU is a recessive disorder that affects 1/10000 babies in the United States. Assuming this population is in Hardy-Weinberg equilibrium for this gene what percentage of the U.S. are heterozygous for this gene?

  11. And again • If 9 out of 100 of an African population is born with a severe form of sickle-cell anemia (ss), what percentage of the population will be more resistant to malaria because they are heterozygous(Ss) for the sickle-cell gene? Assume the population is in Hardy Weinberg Equilibrium!

  12. And Again Again Cystic fibrosis is a recessive condition that affects about 1 in 2,500 babies in the Caucasian population of the United States. Please calculate the following. • The frequency of the recessive allele in the population. • The frequency of the dominant allele in the population. • The percentage of heterozygous individuals (carriers) in the population.

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