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

Area of Science:

• Evolutionary Biology
• Genetics
• Speciation

Background:

• Hybrid incompatibilities are predicted to arise from negative epistatic interactions between genomic variants in diverged lineages.
• These incompatibilities reduce hybrid viability or fertility, acting as barriers to gene flow.
• Understanding the genetic architecture of these interactions is crucial for speciation research.

Purpose of the Study:

• To genetically map hybrid incompatibilities in natural hybrid populations.
• To investigate the role of mitonuclear interactions in reproductive isolation.
• To understand the evolutionary paths and genetic architecture of incompatibilities.

Main Methods:

• Admixture mapping in natural hybrid populations of swordtail fish (Xiphophorus).
• Identification of genomic regions involved in hybrid incompatibilities.
• Analysis of interactions between nuclear and mitochondrial genomes.

Main Results:

• At least nine genomic regions are involved in mitonuclear incompatibilities.
• Incompatibilities identified involve interactions with X. malinche and/or X. birchmanni mitochondria.
• The strength of selection and impact on gene flow vary among these incompatibilities.

Conclusions:

• Mitonuclear interactions play a significant role in the evolution of reproductive barriers.
• Selection against incompatibilities in hybridizing species is complex.
• This study deepens the understanding of genetic architecture underlying speciation.