Data from: Admixture mapping reveals evidence for multiple mitonuclear incompatibilities in swordtail fish hybrids

How barriers to gene flow arise between closely related species is one of
the oldest questions in evolutionary biology. Classic models in
evolutionary biology predict that negative epistatic interactions between
variants in the genomes of diverged lineages, known as hybrid
incompatibilities, will reduce viability or fertility in hybrids. The
genetic architecture of these interactions and the evolutionary paths
through which they arise have profound implications for the efficacy of
hybrid incompatibilities as barriers to gene flow between species. While
these questions have been studied using theoretical approaches for several
decades, only recently has it become possible to genetically map larger
numbers of hybrid incompatibilities. Here, we use admixture mapping in
natural hybrid populations of swordtail fish (Xiphophorus) to identify
hybrid incompatibilities involving genetic interactions between the
mitochondrial and nuclear genomes. We find that at least nine regions of
the genome are involved in mitonuclear incompatibilities. These
incompatibilities involve interactions between the nuclear genome and the
X. malinche mitochondria, the X. birchmanni mitochondria, or both.
Moreover, they vary in the strength of selection they experience and the
degree to which they limit gene flow in natural hybrid populations. Our
results build a deeper understanding of the complex architecture of
selection against incompatibilities in naturally hybridizing species and
highlight an important role of mitonuclear interactions in the evolution
of reproductive barriers between closely related species.