On the evolution of genetic incompatibility systems. IV. Modification of response to an existing antigen polymorphism under partial selfing.
A 2-locus model of the evolution of self-incompatibility in a population practicing partial selfing is presented. An allele is introduced at a modifier locus which influences the strength of the rejection reaction expressed by the style in response to antigens recognized in pollen. Two causes of inbreeding depression are investigated. First, offspring viability depends solely on the source (self or non-self) of the fertilizing pollen. Second, offspring viability declines with the expression of recessive deleterious alleles, segregating at a third (disease) locus, which exhibit an imperfect association with antigen alleles. Evolutionary changes occurring at the disease locus are not considered in this study. The condition under which a modifier allele that intensifies the incompatibility reaction increases when rare depends upon the number of antigens, the frequency of recessive deleterious alleles at the disease locus, and the level of association between the antigen locus and the disease locus. It is the improvement of viability among offspring derived by outcrossing, rather than the prevention of self-fertilization, that may represent the primary evolutionary function of genetic incompatibility systems.
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Related Subject Headings
- Polymorphism, Genetic
- Mutation
- Inbreeding
- Histocompatibility Antigens
- Genes, Recessive
- Evolutionary Biology
- Biological Evolution
- 4901 Applied mathematics
- 3104 Evolutionary biology
- 3103 Ecology
Citation
Published In
DOI
EISSN
ISSN
Publication Date
Volume
Issue
Start / End Page
Related Subject Headings
- Polymorphism, Genetic
- Mutation
- Inbreeding
- Histocompatibility Antigens
- Genes, Recessive
- Evolutionary Biology
- Biological Evolution
- 4901 Applied mathematics
- 3104 Evolutionary biology
- 3103 Ecology