Analyzing the genome evolution of an asexual wasp

Why are purely asexual animals rarer than sexual organisms? Asexual lineages lack the genetic recombination of sexuals and are predicted to be unable to prevent the accumulation of deleterious mutations. This irreversible accumulation of mutations is predicted to push asexuals into extinction. In this thesis, I present evidence for increased mutation accumulation in the putative asexual parasitoid wasp Diachasma muliebre through genomic comparisons with its close, sexually-reproducing relatives. I detect and quantify the mutation accumulation present in D. muliebre by showing that D. muliebre has more genes with changes to the protein-coding sequences of the DNA than does the sexual relative Diachasma ferrugineum. I also tested for evidence of mutation accumulation in the nuclear-encoded mitochondrial genes (NEMGs) in D. muliebre. The NEMGs code for proteins that are exported from the nucleus to the mitochondria. The NEMGs in this study encode the proteins used in the OXPHOS complexes, the five protein complexes that are used to produce the majority of chemical energy in the cell. Though I compared NEMGs of D. muliebre and D. ferrugineum through a variety of metrics, I found no evidence of significant mutation accumulation in the D. muliebre nuclear encoded mitochondrial genes. The lack of significant mutation accumulation in the D. muliebre NEMGs may be due to purifying selection or due to the relatively short time of divergence from D. ferrugineum.