Does parental divergence predict reproductive compatibility?

Hybridization between populations or species can have either beneficial or detrimental effects on fitness. If these effects could be predicted based on the genetic or geographical distance between parents, this would be of great use to plant and animal breeders, managers and conservation biologists. The relationship between divergence and compatibility is also increasingly relevant to evolutionary biology, because recent work on the genetic architecture of reproductive isolation has fuelled a renewed interest in speciation rates and processes. Many studies have shown a correlation between parental divergence and both pre- and postzygotic isolation, but this relationship is clearly not strong enough to guide management decisions. Although it has been suggested that the speciation clock might tick at similar rates in different taxa, this appears to be far from true, because the divergence times resulting in hybrid vigor, outbreeding depression or partial reproductive compatibility vary widely both within and among taxonomic groups.