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Unformatted text preview: migration by looking at the frequency of an allele that is found only in Europeans and not in Africans and com- paring its frequency among blacks in North America. We can use the formula for the change in gene frequency from migration if we modify it slightly to account for the fact that several generations of admixture have taken place. If the rate of admixture has not been too great, then (to a close order of approximation) the sum of the single-generation migration rates over several genera- tions (let’s call this M ) will be related to the total change in the recipient population after these several genera- tions by the same expression as the one used in Box 19-4 for changes due to a single generation of migration. If, as before, P is the allelic frequency in the donor popu- lation and p is the original frequency among the recipi- ents, then D p total 5 M ( P 2 p ) so For example, the Duffy blood group allele Fy a is absent in Africa but has a frequency of 0.42 in whites from the state of Georgia. Among blacks from Georgia, the Fy a frequency is 0.046. Therefore, the total migration of genes from whites into the black population since the...
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This note was uploaded on 01/10/2011 for the course BIOL BIOL taught by Professor Johnson during the Spring '08 term at Aberystwyth University.
- Spring '08