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bioRxiv · 10.1101/2025.03.07.642014

Biodiversity modulates the size-abundance relationship in changing environments

Gjoni, V.·Altermatt, F.·Garnier, A.·Palamara, G. M.·Seymour, M.·Pontarp, M.·Pennekamp, F.
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Abstract

Organismal abundance tends to decline with increasing body size. Metabolic theory links this size structure with energy use and productivity, postulating a size-abundance slope of -0.75 that is invariant across environments. We tested the robustness of this relationship across gradients of protist species richness (1-6 species), temperature (15-25 {degrees}C), and time. Using replicated microcosms, we provide an empirical test of how temperature and biodiversity jointly shape the cross-community scaling relationship (CCSR). While our results support the expected of slope -0.75, we also found interactive effects showing the relationship is not invariant. Warming altered abundance scaling with size depending on richness; in high-richness communities, temperature favoured small protists, steepening the CCSR slope. These context-dependent responses emerged over time, suggesting a role of size-dependent species interactions in shaping responses to environmental change. Our findings demonstrate that cross-community size scaling is not fixed but shifts dynamically with ecological context.

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Gjoni, V., Altermatt, F., Garnier, A., Palamara, G. M., Seymour, M., Pontarp, M., Pennekamp, F.. 2025-03-12. Biodiversity modulates the size-abundance relationship in changing environments. https://doi.org/10.1101/2025.03.07.642014

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