Relaxing the zero-sum assumption in neutral biodiversity theory

Area of Science:

• Ecology
• Theoretical Biology
• Biodiversity Science

Background:

• The standard neutral model of biodiversity by Hubbell assumes a zero-sum condition, implying a constant total number of individuals and coupling species abundances.
• Previous work demonstrated that a neutral model without species coupling shares the same sampling formula as the standard model.
• This suggests practical equivalence in predicting biodiversity patterns.

Purpose of the Study:

• To investigate if the equivalence between neutral models with and without the zero-sum assumption extends to models with community-level density-dependence.
• To explore the implications of this equivalence for the robustness and interpretability of neutral biodiversity models.

Main Methods:

• Mathematical modeling of neutral biodiversity dynamics.
• Comparison of sampling formulas and equilibrium properties of different neutral model formulations.
• Analysis of models incorporating community-level density-dependence.

Main Results:

• The equivalence between neutral models with and without the zero-sum assumption can be extended to a class of models with community-level density-dependence.
• This demonstrates robustness in neutral biodiversity theory, indicating insensitivity to specific interaction mechanisms.

Conclusions:

• Neutral biodiversity models exhibit robustness, as different interaction mechanisms may not be distinguishable through species abundance data alone.
• This lack of resolution implies that inferring precise ecological interactions from static biodiversity data may be challenging.