Abstract
Homoploid hybrid speciation is challenging to document because
hybridization can lead to outcomes other than speciation. Thus, some
authors have argued that establishment of homoploid hybrid speciation
should include evidence that reproductive barriers isolating the hybrid
neo-species from its parental species were derived from hybridization.
While this criterion is difficult to satisfy, several recent papers have
successfully employed a common pipeline to identify candidate genes
underlying such barriers and (in one case) to validate their function.
We describe this pipeline, its application to several plant and animal
species, and what we have learned about homoploid hybrid speciation as a
consequence. We argue that—-given the ubiquity of admixture and the
polygenic basis of reproductive isolation—-homoploid hybrid speciation
could be much more common and more protracted than suggested by earlier
conceptual arguments and theoretical studies.