HETEROSIS AS AN EXPLANATION FOR LARGE AMOUNTS OF GENIC POLYMORPHISM

1 Museum of Comparative Zoology, Harvard University, Cambridge, Massachusetts 02138
2 Department of Mathematics, Northeastern University, Boston, Massachusetts 02115

By using both numerical and analytical approaches, we have shown that heterosis alone is not a mechanism for maintaining many alleles segregating at a locus. Even when all heterozygous are more fit than all homozygotes, the proportion of fitness arrays that will lead to a stable, feasible equilibrium of more than 6 or 7 alleles is vanishingly small. More alleles can be maintained if, in addition to heterosis, it is assumed that there is very little variation in fitness from heterozygote to heterozygote, with the ratio of mean heterosis to standard deviation of fitness among heterozygotes in the neighborhood of 10. When such conditions hold, the allelic frequency distribution and equilibrium will be very uniform, with all alleles very close to equal frequency (see PDF). It is much more likely that stable equilibria for multiple alleles will be best explained by multiple niche selection.

Submitted on August 22, 1977




This article has been cited by other articles:


Home page
GeneticsHome page
B. Star, M. V. Trotter, and H. G. Spencer
Evolution of Fitnesses in Structured Populations With Correlated Environments
Genetics, July 1, 2008; 179(3): 1469 - 1478.
[Abstract] [Full Text] [PDF]


Home page
GeneticsHome page
R. J. Stoffels and H. G. Spencer
An Asymmetric Model of Heterozygote Advantage at Major Histocompatibility Complex Genes: Degenerate Pathogen Recognition and Intersection Advantage
Genetics, March 1, 2008; 178(3): 1473 - 1489.
[Abstract] [Full Text] [PDF]


Home page
GeneticsHome page
B. Star, R. J. Stoffels, and H. G. Spencer
Evolution of Fitnesses and Allele Frequencies in a Population With Spatially Heterogeneous Selection Pressures
Genetics, November 1, 2007; 177(3): 1743 - 1751.
[Abstract] [Full Text] [PDF]


Home page
GeneticsHome page
B. Star, R. J. Stoffels, and H. G. Spencer
Single-Locus Polymorphism in a Heterogeneous Two-Deme Model
Genetics, July 1, 2007; 176(3): 1625 - 1633.
[Abstract] [Full Text] [PDF]


Home page
GeneticsHome page
M. V. Trotter and H. G. Spencer
Frequency-Dependent Selection and the Maintenance of Genetic Variation: Exploring the Parameter Space of the Multiallelic Pairwise Interaction Model
Genetics, July 1, 2007; 176(3): 1729 - 1740.
[Abstract] [Full Text] [PDF]


Home page
Mol Biol EvolHome page
M. S. Snoke, T. U. Berendonk, D. Barth, and M. Lynch
Large Global Effective Population Sizes in Paramecium
Mol. Biol. Evol., December 1, 2006; 23(12): 2474 - 2479.
[Abstract] [Full Text] [PDF]


Home page
GeneticsHome page
J. M. Alvarez-Castro and G. Alvarez
Models of General Frequency-Dependent Selection and Mating-Interaction Effects and the Analysis of Selection Patterns in Drosophila Inversion Polymorphisms
Genetics, July 1, 2005; 170(3): 1167 - 1179.
[Abstract] [Full Text] [PDF]


Home page
Infect. Immun.Home page
E. E. McClelland, D. J. Penn, and W. K. Potts
Major Histocompatibility Complex Heterozygote Superiority during Coinfection
Infect. Immun., April 1, 2003; 71(4): 2079 - 2086.
[Abstract] [Full Text]


Home page
Proc. Natl. Acad. Sci. USAHome page
D. J. Penn, K. Damjanovich, and W. K. Potts
MHC heterozygosity confers a selective advantage against multiple-strain infections
PNAS, August 20, 2002; 99(17): 11260 - 11264.
[Abstract] [Full Text] [PDF]


Home page
Proc. Natl. Acad. Sci. USAHome page
E. Nevo
Inaugural Article: Evolution of genome-phenome diversity under environmental stress
PNAS, May 22, 2001; 98(11): 6233 - 6240.
[Abstract] [Full Text] [PDF]