Abstract
The relationship between biodiversity and ecosystem stability has been one of the most actively researched questions in
ecology for three decades, with major theoretical and empirical advances generating a nuanced but increasingly
convergent understanding that higher biodiversity consistently confers greater ecosystem stability across multiple
dimensions and scales. This review synthesises evidence specifically from zoological systems -- focusing on animal
diversity as both a driver and indicator of ecosystem stability -- across 196 primary studies and six major meta-analyses
published between 1994 and 2024. We examine four stability dimensions (resistance, resilience, temporal variability, and
recovery rate) across three animal-dominated ecosystem types (predator-prey food webs, pollinator-plant networks, and
detritivore-mediated nutrient cycling). Meta-analysis of 84 studies confirms that higher animal diversity reduces temporal
variability of community-level productivity by a mean of 38.4% (portfolio effect and functional redundancy mechanisms),
increases resistance to disturbance by 28.4% (insurance effects), and improves post-disturbance recovery rates by
44.8% (functional complementarity in recolonisation). The biodiversity-stability relationship is strongest for functional
diversity relative to taxonomic diversity (mean standardised effect size 0.84 vs. 0.62 respectively) and is significantly
moderated by the identity of functionally unique species: the loss of a single functionally unique animal species reduced
multi-metric stability indices by 24.4 +- 6.8% in experimental systems -- a disproportionate effect far exceeding expected
proportional contributions. These findings reaffirm the conservation-ecology nexus: preserving animal diversity is not
merely an ethical obligation but an ecological necessity for maintaining ecosystem stability and the services that depend
on it.