There are many types of genetic mutations and they can have different effects on an organism's fitness. For example, small mutations that change DNA base pairs within a gene may have different effects than mutations that change the number of copies of a gene. This research will shed light on the fundamental question: how do different types of genetic mutations contribute to the evolution of the enormous biodiversity found on earth? Surprisingly, the answer to this question remains unclear. In studies of a unicellular organism, this research will find the rate at which different types of mutations happen and look at the effects of these mutations on organisms' fitness. The results of this research will help to clarify the process of mutation and its role in generating diversity. This research will make possible the training in modern genomic methods of a mid-career scientist and several underrepresented minority and first-generation college students.
Previous studies of mutation accumulation in a microbial eukaryote, the ciliate Tetrahymena thermophila, revealed a surprisingly low base-substitution mutation rate. This rate was so low that it could not account for the observed changes in fitness over the course of an experiment, indicating that there must be other types of mutations responsible for the observed changes in fitness. To determine the relative importance of different types of mutations in generating fitness variance, this research will measure the rates of base-substitution, structural, and mitochondrial mutations in T. thermophila, using these previously generated mutation accumulation lines. New genomic analyses of these lines will determine which types of mutations are most frequent and, by comparison to phenotypic data, will determine which types have the potential to generate the most variance in fitness-related traits. The results of these analyses will provide valuable insight into the types of mutations most responsible for evolutionary novelty.
This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.
