THE EFFECTS OF OVERDOMINANCE ON LINKAGE IN A MULTILOCUS SYSTEM

1 National Institute of Genetics, Mishima, 411 Japan and National Institute of Environmental Health Sciences Research Triangle Park, North Carolina, U.S.A.

Computer simulations were performed with overdominant multiple alleles among tightly linked multiple loci under a multiplicative fitness model. The quantity X2/N(n — 1) was introduced as a new measure of linkage disequilibrium which, unlike previously available measures, can be applied to multiple allele models, where N is the sample size, and n is the number of alleles at the locus possessing fewest alleles. Simulations showed that (1) With multiple (three or four) alleles, the approach to stable disequilibrium is slower and the amount of disequilibrium established is weaker than in a two allele system. (2) The number of complementary chromosomes is a function of number of alleles and of population size. (3) As population size increases, the rate of the approach to stable disequilibrium is slower. (4) There is an optimum selection coefficient which minimizes the transient fixation probability of alleles when linkage is present. (5) The absence of linkage disequilibrium is in most cases not a practical method of testing the hypothesis of balancing selection of genetic polymorphisms because it depends strongly on population size in determining linkage disequilibria.

Submitted on December 8, 1975
Revised on November 29, 1976




This article has been cited by other articles:


Home page
GeneticsHome page
D. V. Zaykin, A. Pudovkin, and B. S. Weir
Correlation-Based Inference for Linkage Disequilibrium With Multiple Alleles
Genetics, September 1, 2008; 180(1): 533 - 545.
[Abstract] [Full Text] [PDF]


Home page
J DAIRY SCIHome page
M. Sargolzaei, F. S. Schenkel, G. B. Jansen, and L. R. Schaeffer
Extent of Linkage Disequilibrium in Holstein Cattle in North America
J Dairy Sci, May 1, 2008; 91(5): 2106 - 2117.
[Abstract] [Full Text] [PDF]


Home page
Poult. Sci.Home page
M. Soller, S. Weigend, M. N. Romanov, J. C. M. Dekkers, and S. J. Lamont
Strategies to Assess Structural Variation in the Chicken Genome and its Associations with Biodiversity and Biological Performance
Poult. Sci., December 1, 2006; 85(12): 2061 - 2078.
[Abstract] [Full Text] [PDF]


Home page
GeneticsHome page
E. M. Heifetz, J. E. Fulton, N. O'Sullivan, H. Zhao, J. C. M. Dekkers, and M. Soller
Extent and Consistency Across Generations of Linkage Disequilibrium in Commercial Layer Chicken Breeding Populations
Genetics, November 1, 2005; 171(3): 1173 - 1181.
[Abstract] [Full Text] [PDF]