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 reduce hybrid fitness, acting as barriers to gene flow.
• Understanding the genetic basis of these incompatibilities is key to explaining species divergence.
• Recent advances allow for genetic mapping of hybrid incompatibilities in natural populations.

Purpose of the Study:

• To genetically map hybrid incompatibilities in natural populations of swordtail fish (Xiphophorus).
• To investigate the role of interactions between mitochondrial and nuclear genomes in reproductive isolation.

Main Methods:

• Admixture mapping was employed in natural hybrid populations.
• Identification of genomic regions involved in mitonuclear incompatibilities.

Main Results:

• At least nine genomic regions were implicated in mitonuclear incompatibilities.
• These incompatibilities 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 incompatibilities play a significant role in the evolution of reproductive barriers.
• The study provides insights into the complex genetic architecture of selection against incompatibilities in hybridizing species.