Selection Increases Mitonuclear DNA Discordance but Reconciles Incompatibility in African Cattle.

Area of Science:

• Genomics
• Evolutionary biology
• Animal science

Background:

• Mitochondrial function depends on nuclear and mitochondrial DNA gene interactions.
• Mitonuclear incompatibility can reduce fitness in hybrids and admixed populations.
• African admixed cattle exhibit sex-biased admixture with taurine mitochondrial DNA and zebu nuclear genomes.

Purpose of the Study:

• To investigate the ancestry and distribution of nuclear genes related to mitochondrial oxidative phosphorylation in African admixed cattle.
• To understand the mechanisms reconciling mitonuclear incompatibility in this admixed population.

Main Methods:

• Utilized local ancestry inference to identify nuclear gene origins.
• Analyzed gene distribution patterns associated with mitochondrial function.
• Examined potential roles of mitochondrial DNA copy number variation and gene expression regulation.

Main Results:

• Most nuclear genes involved in mitonuclear interactions are under selection and of humped zebu (Bos indicus) ancestry.
• Mitochondrial DNA copy number variations and gene expression regulation likely aided in restoring mitochondrial function.
• Some nuclear mitochondrial genes of taurine (Bos taurus) ancestry may stem from ancient African aurochs introgression, potentially aiding adaptation to pathogens.

Conclusions:

• Cattle's successful adaptation in Africa involved complex mechanisms including adaptive introgression.
• Selection of ancestral mitochondria-related genes, mitochondrial DNA copy number variation, and gene expression regulation were key factors.
• Ancient introgression may have provided adaptive advantages for local environments.