Lewontin collected data on the frequencies of different alleles at various nuclear loci in different

Lewontin collected data on the frequencies of different alleles at various nuclear loci in different

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Lewontin collected data on the frequencies of different alleles at various nuclear loci in different human populations. These populations were nested into larger groups we know as races , and the various races can be nested further into the larger group we call the species Homo sapiens . With data on allele frequencies in each population, Lewontin could ask how much additional variation is added to the unit in question by pooling together the data from all populations within races, or at one level up the hierarchy, by pooling all the data from within races to one large species sample. To quantify what proportion of the total genetic variation within humans, a measure of "heterozygosity" was used similar to H = 2pq (or [1- (allele frequency i ) 2 ] for i different alleles; in the paper the very similar
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Unformatted text preview: Shannon-Weaver index was used). The numbers obtained from this formula provide a measure of genetic diversity at each of the many loci tabulated by Lewontin. Four points are relevant in thinking about this measure of "diversity": 1) a locus with only one allele will have H = 0; 2) the greatest diversity will be when all alleles are equally frequent (p=q=0.5 for 2 alleles; p 1 =p 2 =p 3 =p 4 =0.25 for 4 alleles); 3) diversity will increase as the number of alleles increases (the 4 allele case above is more 'diverse' than the 2 allele case); 4) diversity is aconvex function of allele frequency (a diversity measure from a pooled sample obtained by combining alleles from two different populations will be greater than the average of the two diversity measures from each population)....
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This note was uploaded on 11/06/2011 for the course BIO BSC1010 taught by Professor Gwenhauner during the Fall '10 term at Broward College.

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