Ploidy is associated with multielemental reorganization across soft and mineralized body compartments.

Polyploidy alters nuclear DNA content, gene dosage and cellular organization, but its consequences for organismal chemistry remain poorly resolved, particularly in animals. Because nucleic acids and associated cellular machinery require coordinated allocation of multiple elements, ploidy-associated differences may extend beyond the well-established consequences for body phosphorus content to broader multielemental organization. We tested this hypothesis in the New Zealand mudsnail (Potamopyrgus antipodarum), which features within-population ploidy polymorphism, and exhibits strong compartmentalization between metabolically active soft tissue and mineralized shell. We quantified multielemental composition of soft tissue and shell and analysed allocation using additive log-ratios anchored to the measured elemental pool. Most multielemental variance was harboured in tissue versus shell, confirming distinct ionomic regimes for these two fundamental components of the molluscan body. Across both soft tissue and shell, ploidy was associated with significant redistribution of relative elemental allocation despite weak single-element effects. Ploidy-associated imbalances differed between shell and soft tissue, consistent with elemental physiology in inert and active tissues. Together, these results are consistent with a scenario where ploidy level is associated with subtle but coordinated redistribution of elemental allocation across biological compartments.