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Hardy-Weinberg Principle Last day we left off talking about populations… Populations geneticists are able to quantify the total number of alleles within a population ==this is known as the gene pool They are able to accomplish this by measuring each allele frequency, which is the proportion of gene copies in a population for a given allele Therefore evolutionary changes in populations can be quantitatively measured by looking for changes in allele frequencies In terms of evolution, would the dominant form of a moth wing become more and more common over time? Do allele frequencies remain constant or change over time? These questions were answered independently (think Darwin vs. Wallace) by a mathematician named Hardy and physicist named Weinberg== thus Hardy-Weinberg principle Allele frequencies will not change over time (generation-generation) if the following conditions are met: I. The population is very large II. Mating opportunities are equal III. No mutations occur IV. No migration occurs V. All individuals have an equal chance at reproductive success==no natural selection The H-W-P is often expressed using the following equation (for a gene with only 2 alleles==A/a): let p=frequency of A and q=frequency of a, then p+q=1 (p+q)2= 1 p2 + 2pq + q2 = 1, where p2 = frequency of AA; 2pq= frequency of Aa; and q2 = frequency of aa Note: genotype frequencies will remain the same from generation to generation as long mating is random Pgs 547-549 Pg 549 PP’s #1-3 Quiz Tomorrow -self quiz -review #1-4, 7, 8, 10, 15