Whole-Genome Sequence of Potamopyrgus antipodarum-A Model System for the Maintenance of Sexual Reproduction-Reveals a...

Key unanswered questions in biology center on the causes, consequences, and maintenance of sexual reproduction ("sex"). Genome-driven processes are central to the evolutionary and genetic mechanisms inherent to sex, making genomic resources a fundamental part of answering these questions. We present the first genome assembly for a species that is uniquely well-suited for the study of (a)sex in nature, Potamopyrgus antipodarum. This New Zealand snail is unusual in featuring multiple separate transitions from obligately sexual to obligately asexual reproduction, leading to the coexistence of phenotypically similar sexual and asexual forms, a feature that is required to directly study the maintenance of sex. These separately derived asexual lineages constitute separate evolutionary experiments, providing a powerful means of characterizing how the absence of sex affects genome evolution. Our genome assembly provides critical steps toward understanding the causes and consequences of sex in this system and important resources for the rapidly growing P. antipodarum and molluscan genomics research community. In characterizing this genome, we uncovered unexpected evidence for a recent whole-genome duplication (WGD) in P. antipodarum. This discovery sets the stage for using P. antipodarum to evaluate processes of rediploidization following WGD and to assess whether WGD might drive transitions to asexuality.