| Abstract: | Despite mitochondrial DNA being one of the most popular and powerful molecular markers used to study eukaryotic evolution, much about its biology remains poorly understood. Mitochondrial genomes are challenging to engineer, reducing the power of experiments aimed at disentangling mitochondria⁰́₉s complex and dynamic biology. In this dissertation, we take advantage of both long-term mutation accumulation experiments ⁰́₄ which spontaneously generate new deletion-bearing mitotypes in Caenorhabditis elegans ⁰́₄ and the large catalog of C. elegans natural isolates. This allows us to avoid the difficulty of engineering mitochondrial genomes and explore how selection shapes the fate of new mitochondrial mutations. We first demonstrate the selfish nature of a mitotype bearing a deletion in the ctb-1 gene (⁸́⁶ctb-1), namely its transmission advantage and host fitness costs. ⁸́⁶ctb-1 is then used to highlight the importance of population size for the intracellular dynamics of mitochondrial mutations. Next, we disentangle the mutational history of ⁸́⁶ctb-1. In doing so, we found that selfish drive can be seen in a variety of classes of mitochondrial mutations, and that some mutations may hitchhike to high frequency by arising on a mitotype bearing a selfish mutation. We then demonstrate the selfish nature of another deletion-bearing mitotype and compare its intracellular dynamics to that of ⁸́⁶ctb-1. Finally, we created lines of C. elegans bearing mutations in their sex determination pathways, and in key components of the electron transport chain. We then used these lines to determine if any of the electron transport chain mutations had sex system-specific or male-specific detrimental effects. The electronic version of this dissertation is accessible from https://hdl.handle.net/1969.1/197106 |
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