De novomutation rates in sticklebacks

Abstract

AbstractMutation rate is a fundamental parameter in population genetics. Apart from being an important scaling parameter for demographic and phylogenetic inference, it allows one to understand at what rate new genetic diversity is generated and what is the expected level of genetic diversity in a population at equilibrium. However, except for well-established model organisms, accurate estimates ofde novomutation rates are available for a very limited number of organisms from the wild. We estimated mutation rates (µ) in two marine populations of the nine-spined stickleback (Pungitius pungitius) with the aid of several 2- and 3-generational family pedigrees, deep (>50×) whole genome re-sequencing and a high-quality reference genome. After stringent filtering, we discovered 295 germline mutations from 106 offspring translating toµ= 4.64 × 10−9andµ= 4.08 × 10−9per base, per generation, in the two populations, respectively. Twenty percent of the mutations were shared by full-sibs showing that the level of parental mosaicism was relatively high. Since the estimatedµwas 3.2 times smaller than the commonly used substitution rate, recalibration withµled to substantial increase in estimated divergence times between different stickleback species. Our estimates ofde novomutation rate should provide a useful resource for research focused on fish population genetics and that of sticklebacks in particular.