Pacific oysters (Crassostrea gigas) dramatically recalibrate the model for the upper limit of the eukaryotic mutation rate

January 3 – Febuary 28, 2021

Meeting Abstract

S2-9  Mon Jan 4 16:30 – 17:00  Pacific oysters (Crassostrea gigas) dramatically recalibrate the model for the upper limit of the eukaryotic mutation rate Churches, N; Chancellor, J; Chang, P; Nuzhdin , S*; Univ. Southern California; Univ. Southern California; Seedoffshore, LLC; Univ. Southern California

The study of bivalves is currently enjoying a significant increase in both private and scientific interest, and duly so. Bivalves have historically been implemented in studies investigating strange evolutionary phenomenon (e.g. Sweepstakes Reproductive Success), rare genetic transmission mechanisms (e.g. doubly-uniparental mitochondrial inheritance), sentinel species for ocean acidification response, and more recently as a sustainable food source for the future and domestication target. The generational mutation rate in the emerging bivalve model organism the Pacific oyster, Crassostrea gigas, had previously been hypothesized to be among the highest yet estimated in eukaryotes, however empirical proof was absent. The study presented for consideration here uses whole genome sequencing data from trios (mother, father, and a set of offspring) to directly and empirically estimate per nucleotide mutation rate for the first time in mollusks, using the Pacific oyster. We found that the Pacific oyster has a mutation rate that is 2-3 orders of magnitude larger than any yet reported among eukaryotes (~10-5 per base per generation). This finding shifts the upper limit of hypothesized mutation rate for eukaryotes, similarly, 2-3 orders of magnitude, and indicates that perhaps organisms undergoing type III/r-selected survivorship within chaotic oceanic environments may be under selective pressure to decrease or eliminate basic molecular functions, including DNA replication fidelity. Our findings implicate the use of the Pacific oyster an ideal system for studying novel DNA replication machinery, and will have a significant impact for evolutionary theory studies and selective breeding programs alike.

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