Intratetrad mating and the evolution of linkage relationships.
Mating among the immediate products of meiosis (intratetrad mating) is a common feature of many organisms with parthenogenesis or with mating-type determination in the haploid phase. Using a three-locus deterministic model we show that intratetrad mating, unlike other systems of mating, allows sheltering of deleterious recessive alleles even if there is only partial linkage between a mating locus and a load locus. Moreover, modifiers that reduce recombination between the load and mating-type locus will spread to fixation, even when there is no linkage disequilibrium between these loci in the population as a whole. This seeming contradiction to classical expectation is because partial linkage generates linkage disequilibrium among segregating loci within a tetrad, which then acts as the "mating unit."
Antonovics
Janis
J
Department of Biology, University of Virginia, Charlottesville, Virginia 22904, USA. antonovics@virginia.edu
Abrams
Joseph Y
JY
D000483:Alleles; D003198:Computer Simulation; D006579:Heterozygote; D008540:Meiosis / Q000235:genetics*; D008957:Models, Genetic; D009154:Mutation / Q000235:genetics*; D012098:Reproduction / Q000235:genetics; D012641:Selection, Genetic