What does the term "epistasis" refer to?

The term "epistasis" refers specifically to the interaction between genes in which the effect of one gene is masked or suppressed by another gene. This phenomenon is significant in genetics because it can influence the way traits are expressed in an organism. For example, in a scenario where two genes determine a particular trait, one gene may be dominant over the other and therefore completely overshadow its effects. This interaction can complicate the inheritance patterns that Mendelian genetics would typically predict, leading to a variety of phenotypic outcomes.

The understanding of epistasis is crucial for geneticists because it helps explain variations in observed traits that may not be solely attributable to single-gene effects. This concept is relevant in fields such as breeding, evolutionary biology, and medical genetics, where recognizing gene interactions can lead to better predictions of trait inheritance and potential disorders.