Evidence for Balanced Linkage of X Chromosome Polygenes in a Natural Population of Drosophila |
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Authors: | J. N. Thompson-Jr J. J. Hellack R. R. Tucker |
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Affiliation: | Department of Zoology, University of Oklahoma, Norman 73019. |
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Abstract: | Extensive levels of polygenic variation can be maintained in a population without creating a severe segregational load. One way to account for this is that the alleles are arranged on a chromosome so that different regions balance each other phenotypically. To test whether this occurs in a natural population, we isolated ten Drosophila melanogaster X chromosomes and mapped regions of polygenic activity affecting sternopleural bristle number. The chromosomes fell into a small number of groups based upon the similarity of their distributions of polygenic activity. The results are consistent with a model in which a large proportion of the variation can be attributed to a small number of segregating chromosome regions and in which the chromosomes show internal balance. |
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