AP Biology—Unit 8 Name: Hardy-Weinberg Equilibrium Introduction Evolution occurs in populations of organisms and involves variation in the population, heredity, and differential survival and reproduction. One way to study evolution is to study how the frequency of alleles in a population changes from generation to the inheritance patterns of generation. In other words, you can ask “What are alleles, not just from two parental organisms, but also in a can then explore how allele population?” You frequencies change in populations and how these changes might predict what will happen to a population in the future. Mathematical models and computer simulations are tools used to explore the complexity of biological systems that might otherwise be difficult or impossible to study. In 1908, one such scheme, whereby evolution could be viewed as changes in the frequency of alleles in a population of organisms, was independently suggested by G.H. Hardy and W. Weinberg. In this scheme, if A and a are alleles for a particular gene locus and each diploid individual has two such loci, then p can be designated as the frequency of the A allele and q as the frequency of the a allele. In a population of 100 individuals (each with two loci/alleles) in which 60% of the alleles are A, 40% of the alleles would be a. Consequently, the frequencies for these alleles would be as such: p = 0.6 q = 0.4 These are referred to as the allele frequencies in the population and we can conclude that: p + q = 1 (Allele Frequency Equation) The frequencies of the possible genotypic / diploid combinations of these alleles (AA, Aa, aa) can be expressed by an equation, but a Punnet square to see the possibilities. let’s first develop p = 0.6 q = 0.4 p = 0.6 q = 0.4 The probability of two A alleles combining in one organism in the next generation is p2. The probability of two a alleles combining in one organism in the next generation is q2. The probability of a combination of Aa is p*q, as is the probability of aA , for a total of 2pq. Consequently, the formula that predicts the genotypic frequencies for the next generation in a population is: (p + q)2 = 1, which works out to be p2 + 2pq + q2 = 1 (Genotypic Frequency Equation)
AP Biology—Unit 8 Name: Hardy-Weinberg Equilibrium Introduction Evolution occurs in populations of organisms and involves variation in the population, heredity, and differential survival and reproduction. One way to study evolution is to study how the frequency of alleles in a population changes from generation to generation. In other words, you can ask “What are the inheritance patterns of alleles, not just from two parental organisms, but also in a population?” You can then explore how allele frequencies change in populations and how these changes might predict what will happen to a population in the future. Mathematical models and computer simulations are tools used to explore the complexity of biological systems that might otherwise be difficult or impossible to study. In 1908, one such scheme, whereby evolution could be viewed as changes in the frequency of alleles in a population of organisms, was independently suggested by G.H. Hardy and W. Weinberg. In this scheme, if A and a are alleles for a particular gene locus and each diploid individual has two such loci, then p can be designated as the frequency of the A allele and q as the frequency of the a allele. In a population of 100 individuals (each with two loci/alleles) in which 60% of the alleles are A, 40% of the alleles would be a. Consequently, the frequencies for these alleles would be as such: p = 0.6 q = 0.4 These are referred to as the allele frequencies in the population and we can conclude that: p + q = 1 (Allele Frequency Equation) The frequencies of the possible genotypic / diploid combinations of these alleles (AA, Aa, aa) can be expressed by an equation, but let’s first develop a Punnet square to see the possibilities. p = 0.6 q = 0.4 p = 0.6 q = 0.4 The probability of two A alleles combining in one organism in the next generation is p2. The probability of two a alleles combining in one organism in the next generation is q2. The probability of a combination of Aa is p*q, as is the probability of aA , for a total of 2pq. Consequently, the formula that predicts the genotypic frequencies for the next generation in a population is: (p + q)2 = 1, which works out to be p2 + 2pq + q2 = 1 (Genotypic Frequency Equation)
14-15%20H-W%20Lab.docx