When will hybridization bring long-term benefits?

Hybridization between distinct populations injects genetic variation, which can bring fitness benefits. However, these benefits often appear as F1 heterosis, and might not persist into later generations; especially since, as emphasized by classical theories, heterosis can be caused in several different ways. Here, we study the long-term outcomes of hybridization, using a model that allows us to tune several properties of the genetic variation, including the strength and architecture of heterosis, thereby unifying the classical theories. Results suggest that long-term outcomes depend mainly on the variance in epistasis, which determines the ruggedness of the fitness landscape, but without affecting the heterosis. Together, results suggest that the study of heterosis may tell us relatively little about the long-term outcomes of hybridization, and that hybridization might bring benefits more often than has been assumed.