Mutation Accumulation in an Asexual Relative of Arabidopsis

• Published in: PLoS genetics Vol. 13; no. 1; p. e1006550
• Main Authors: Lovell, John T., Williamson, Robert J., Wright, Stephen I., McKay, John K., Sharbel, Timothy F.
• Format: Journal Article
• Language: English
• Published: United States Public Library of Science 09.01.2017; Public Library of Science (PLoS)
• Subjects: Arabidopsis; Arabidopsis thaliana; Biology and Life Sciences; Brassicaceae; Brassicaceae - classification; Brassicaceae - genetics; Endangered & extinct species; Evolution, Molecular; Evolutionary biology; Funding; Gene mutation; Genetic aspects; Genome, Plant; Genomes; Haplotypes; Mutation; Mutation Rate; Phylogeny; Physiological aspects; Protection and preservation; Reproduction, Asexual; Research and Analysis Methods; Selection, Genetic; Studies
• ISSN: 1553-7404; 1553-7390; 1553-7404
• DOI: 10.1371/journal.pgen.1006550

Asexual populations experience weaker responses to natural selection, which causes deleterious mutations to accumulate over time. Additionally, stochastic loss of individuals free of deleterious mutations can lead to an irreversible increase in mutational load in asexuals (the "click" in Muller's Ratchet). Here we report on the genomic divergence and distribution of mutations across eight sympatric pairs of sexual and apomictic (asexual) Boechera (Brassicaceae) genotypes. We show that apomicts harbor a greater number of derived mutations than sympatric sexual genotypes. Furthermore, in phylogenetically constrained sites that are subject to contemporary purifying selection, the ancestral, conserved allele is more likely to be retained in sexuals than apomicts. These results indicate that apomictic lineages accumulate mutations at otherwise conserved sites more often than sexuals, and support the conclusion that deleterious mutation accumulation can be a powerful force in the evolution of asexual higher plants.