Chromosome-scale genome dynamics reveal signatures of independent haplotype evolution in the ancient asexual mite Platynothrus peltifer

Abstract

Some unique asexual species persist over time and contradict the consensus that sex is a prerequisite for long-term evolutionary survival. How they escape the dead-end fate remains enigmatic. Here, we generated a haplotype-resolved genome assembly on the basis of a single individual and collected genomic data from worldwide populations of the parthenogenetic diploid oribatid mite Platynothrus peltifer to identify signatures of persistence without sex. We found that haplotypes diverge independently since the transition to asexuality at least 20 million years ago in European lineages, contrasting Japanese and Canadian lineages. Multiple lines of evidence indicate conservation of one haplotype copy and relaxed selection in the other for the ancient asexual lineages. These findings highlight the evolutionary genomic singularities of ancient asexual oribatid mites that may have contributed to escaping the early demise typically associated with asexuality.