Making a Murderer: The Evolutionary Framing of Hybrid Gamete-Killers

Recent molecular investigations of hybrid incompatibilities have revealed fascinating patterns of genetic interactions that have been interpreted as the remnants of a history of selfish evolution. Instead of framing hybrid incompatibilities in light of genetic conflict, we advocate assuming their innocence. Researchers must build a strong theory for each case, supported by population genetic evidence, such that the role of conflict in the evolution of a hybrid incompatibility can be proven beyond reasonable doubt. This will require careful investigation of the evolutionary history of these incompatibilities, a reckoning of how the reproductive biology of study organisms impacts on the likelihood of genetic conflict, and molecular evidence of the rapid selfish spread of these alleles.