Date of this Version
Saline, C. 2022. Mitochondrial-Nuclear Coevolution in the Oxidative Phosphorylation Proteins of Mammals. Undergraduate Honors Thesis. University of Nebraska-Lincoln.
The endosymbiotic theory holds that an ancestral eukaryote engulfed an ancient mitochondrial precursor and kickstarted a coevolutionary relationship unto the current state of codependency. The two genomes’ contrasting modes of inheritance, proofreading, and effective population sizes contribute to variation in the mitochondrial and nuclear nonsynonymous-to-synonymous amino acid substitution rates across gene sets depending on their functional relatedness. The compensatory model hypothesizes that the closer the gene products of the two genomes must interact, the more correlated their substitution rates must be to maintain organismal fitness. The general trend in vertebrates is that the mitochondria “drives” the two genomes’ coevolution with more nonsynonymous mutations while the nucleus must “catch up” with corrective mutations to preserve organismal function. To test this model, we calculated Spearman’s Rho evolutionary rate correlations for nuclear, nuclear-encoded mitochondrially-targeted, nuclear-encoded mitochondrially-targeted oxidative phosphorylation, and mitochondrial genes in 29 mammalian species and found evidence of coevolution. These results help document metazoan evolutionary history and diversity regarding mitonuclear trends across taxa and have implications in assisted human reproduction to avoid mitochondrial diseases.