Mutation rates and genome evolution in asexual and sexual reproduction organisms
by Yixiang Zhang | Shuai Zhan | Center for Excellence in Molecular Plant Science (CEMPS) /Institute of Plant Physiology and Ecology, Chinese Academy of Sciences (CAS) | Center for Excellence in Molecular Plant Science (CEMPS) /Institute of Plant Physiology and Ecology, Chinese Academy of Sciences (CAS)
Abstract ID: 192
Event: The 3rd AsiaEvo Conference
Topic: Why sex? insights from asexual genomes
Presenter Name: Yixiang Zhang

The origin of genetic variation in biology is a fundamental driving force of evolution. Evaluating the mutation rate and mutation types within species is crucial for a comprehensive understanding of evolution. In recent years, with the widespread use of whole-genome sequencing, it has become possible to directly estimate mutation rates in both sexually and asexually reproducing species within the tree of life. Understanding the variations in mutation rates between sexual and asexual reproduction in different species sheds light on the choices made during the species' evolutionary processes. Here, we estimated the spontaneous mutation rate for blue alfalfa aphid (Acyrthosiphon kondoi), which is 9.33E-10 (95% CI: 6.23e-10, 1.32e-09) per haploid genome per parthenogenic generation. We accomplished this by conducting a mutation accumulation experiment. Additionally, we estimated the rates of insertion and deletion mutations to be 9.98E-11 (95% CI: 1.47e-11 to 1.85e-10).We also compared per-generation mutation rates in 152 species, including 18 bacteria,  118 eukaryotes, 8 plant species, and 8 avian species. Among these, 43 species reproduce asexually, while 109 reproduce sexually. The results revealed that, in most branches of the tree of life, species reproducing sexually exhibit significantly higher mutation rates compared to asexual species. However, within the arthropod group Branchiopoda, some asexual species display relatively high mutation rates. Furthermore, our analysis indicated that asexual species typically possess smaller genomes and lower mutation rates due to their longer generation times when considering phylogenetic relationships. Notably, although nucleotide diversity is inversely correlated with effective population size, species with larger long-term effective population sizes tend to have lower per-generation mutation rates, supporting the drift barrier hypothesis. However, asexual species do not conform to this trend. In summary, our comparative analysis provides ecological insights into the evolution of mutation rates in animals, by examining mutation rate variations in sexual and asexual reproduction based on species' evolutionary trees.