epistaticadj.

1907 W. Bateson in Science 15 Nov. 653/2 Till lately we spoke of the relations between the gray color of the mouse to the black color in terms of dominance. Those terms, strictly speaking, should only be applied to members of the same allelomorphic pair. We can perhaps best express the relation between the gray and the black by the use of the metaphor ‘higher and lower’, and I therefore suggest the term epistatic as applicable to characters which have to be, as it were, lifted off in order to permit the lower or hypostatic character to appear.

1909 W. Bateson Mendel's Princ. Heredity (new ed.) ii. 41 The magenta shades [in Primula] have a factor epistatic to crimson and pink.

1949 C. D. Darlington & K. Mather Elements of Genetics vii. 157 A gene removing an organ is..obviously epistatic to one modifying that organ.

1993 N.Y. Times 7 Sept. c7/3 ‘It could be a polygenic trait, meaning that more than one position is involved, or an epistatic interaction, where a given pair of genes stands upon or masks or hides another pair of genes,’ Dr. Gaynor said.

2004 C. W. Smith et al. Corn 307 Estimation of variance components in corn populations with broad genetic variance indicated that additive effects are more important than dominance or epistatic effects.