There are two reproductively isolated species of wood white called "L. sinapis" and "L. reali." These two species can mate with each other (heterospecific mating), but it is in their best interest, for the viability and fecundity of their offspring, that they mate only within their species (conspecific mating). Male members of the two species try and court or mate with females of both species with equal frequency, but the females only mate with members of their own species. This female choice has caused the two species to diverge and become reproductively isolated. There is a time and energy cost that the females bear when males of the opposite species attempt to mate with them—this cost has led to females occasionally acquiescing and mating with these males, leading to some degree of between-species hybridization.