(1) These results suggest that future genetic models for the evolution of aging should incorporate the effects of epistasis .(2) Neither earlier study was able to demonstrate a significant effect of epistasis , either positive or negative.(3) For geneticists, epistasis is associated with the limits of the additive model of gene action.(4) This advantage of sex should be especially substantial when mutations interact through negative epistasis .(5) Genetic epistasis of gene expression can also be considered with large sample sizes.(6) Such sites may be indicative of hotspots of recombination or mutation or epistatic selection.(7) Thus, neither allele is epistatic to the other in permitting the occurrence of expansions or contractions.(8) It is known that epistatic selection may produce significant linkage disequilibrium in natural populations.(9) The results suggested that a minimum of two genes with epistatic effects were involved in the genetic control of cleistogamy.(10) This study shows that most hybrid incompatibilities are recessive and epistatic .