Ploidy reorganizes ionomic composition across metabolically active and mineralized tissues.

Genome size, defined as total nuclear DNA content, varies widely within species and can influence cell size, metabolic scaling, and organismal performance. Yet the mechanisms linking genome architecture to phenotype remain unresolved, especially in animals. Because organisms are far-from-equilibrium systems built from interacting chemical elements, genome size variation should reorganize elemental allocation across tissues rather than shift single-element requirements in isolation. We tested this hypothesis in the New Zealand mudsnail (Potamopyrgus antipodarum), which includes co-occurring diploid, triploid, and tetraploid individuals and exhibits strong compartmentalization between metabolically active soft tissue and mineralized shell. We quantified multielemental composition of both tissues and analyzed allocation using additive log-ratios anchored to the measured elemental pool. Tissue type explained most multielemental variance, confirming distinct ionomic regimes for shell and soft tissue. Across tissues, ploidy was associated with significant redistribution of relative elemental allocation despite weak single-element effects. Ploidy-associated imbalances were more pronounced in shell than soft tissue, consistent with long-term integration of elemental fluxes in inert structures and buffering in active tissues. Genome size variation therefore reshapes organismal chemistry through coordinated multielemental redistribution, linking genome architecture to system-level chemical organization.