Phenotypic tolerance for rDNA copy number variation within the natural range of C. elegans

The current paradigm is the understanding of the phenotypic effects of ribosomal DNA (rDNA) copy number variation in model organisms.

This preprint investigates the phenotypic consequences of natural rDNA copy number variation in *C. elegans*, a topic within the current paradigm of understanding the phenotypic effects of rDNA copy number variation. The study focuses on generating new tools and resources to understand genomic interactions with rDNA copy number and its relationship with phenotypic traits. The authors generate recombinant inbred lines (RILs) and near-isogenic lines (NILs) with varying rDNA copy numbers and investigate their effects on various life history traits, such as rRNA abundance, competitive fitness, fertility, lifespan, global transcriptome, and male frequency. Their findings demonstrate that *C. elegans* exhibits a high degree of tolerance for even substantial variations in rDNA copy number, with minimal observable phenotypic consequences under standard laboratory conditions. This research falls under normal science as it operates within the existing paradigm, refines existing tools, and gathers further empirical data to deepen the understanding of the phenotypic effects of rDNA copy number variation. No major anomalies or contradictions to the existing paradigm are observed. While the study does contribute novel resources and expands our understanding of the tolerance of *C. elegans* to rDNA copy number variation, it does not challenge the fundamental understanding of rDNA or its impact on phenotype.
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