Mitonuclear Incompatibility in Swordtail Fish Hybrids

Biologists have identified a lethal mitonuclear hybrid incompatibility in swordtail fish, shedding light on the mechanisms that maintain isolation between species. By studying the Xiphophorus birchmanni and Xiphophorus malinche species, researchers pinpointed two nuclear-encoded genes, ndufs5 and ndufa13, that are lethal when mismatched with the mitochondrial genome of the other species. These incompatibilities affect embryonic development and physiological traits, providing insights into the evolutionary processes driving the emergence of hybrid incompatibilities. The study highlights the significance of mitonuclear interactions in the evolution of hybrid incompatibilities and the impact of historical hybridization on species evolution.