Hybrid dysfunction: population genetic and quantitative genetic perspectives.

In the wake of seminal work by Dobzhansky and Muller, hybrid dysfunction is usually attributed to incompatible mutations in different genes arising in different populations. This Dobzhansky-Muller (D-M) model is among the most important contributions of theoretical population genetics. Here I make formal connections between the D-M model and the quantitative genetic interpretation of hybrid dysfunction as a combination of additive, dominance, and epistatic effects. Concerns over conceptual differences between the two approaches are unwarranted; the D-M model can be expressed as a special case of the statistical model developed for line-cross analysis in quantitative genetics. This unified theoretical framework encourages application of quantitative genetic methods to the study of speciation.