Journal Article

Relative role of deterministic and stochastic determinants of soil animal community: a spatially explicit analysis of oribatid mites

Migliorini, Massimo, Caruso, Tancredi, Taormina, Mauro

2012

Overview

1. Ecologists are debating the relative role of deterministic and stochastic determinants of community structure. Although the high diversity and strong spatial structure of soil animal assemblages could provide ecologists with an ideal ecological scenario, surprisingly little information is available on these assemblages. 2. We studied species-rich soil oribatid mite assemblages from a Mediterranean beech forest and a grassland. We applied multivariate regression approaches and analysed spatial autocorrelation at multiple spatial scales using Moran's eigenvectors. Results were used to partition community variance in terms of the amount of variation uniquely accounted for by environmental correlates (e.g. organic matter) and geographical position. Estimated neutral diversity and immigration parameters were also applied to a soil animal group for the first time to simulate patterns of community dissimilarity expected under neutrality, thereby testing neutral predictions. 3. After accounting for spatial autocorrelation, the correlation between community structure and key environmental parameters disappeared: about 40% of community variation consisted of spatial patterns independent of measured environmental variables such as organic matter. Environmentally independent spatial patterns encompassed the entire range of scales accounted for by the sampling design (from tens of cm to 100 m). This spatial variation could be due to either unmeasured but spatially structured variables or stochastic drift mediated by dispersal. Observed levels of community dissimilarity were significantly different from those predicted by neutral models. 4. Oribatid mite assemblages are dominated by processes involving both deterministic and stochastic components and operating at multiple scales. Spatial patterns independent of the measured environmental variables are a prominent feature of the targeted assemblages, but patterns of community dissimilarity do not match neutral predictions. This suggests that either niche-mediated competition or environmental filtering or both are contributing to the core structure of the community. This study indicates new lines of investigation for understanding the mechanisms that determine the signature of the deterministic component of animal community assembly.

• Publisher: Blackwell Publishing,Blackwell Publishing Ltd,Blackwell
• Subject: Animal and plant ecology / animal communities / Animal ecology / Animal populations / Animal, plant and microbial ecology / Animals / Arachnida / autocorrelation / Biological and medical sciences / Biota / Communities / Community ecology / Community structure / Competition / Data processing / deterministic and stochastic processes / Dispersal / Drift / Ecologists / Ecology / Ecosystem / environmental factors / Fagus / filters / Forest habitats / Forest soils / Forests / Fundamental and applied biological sciences. Psychology / General aspects / Grasses / Grasslands / Immigration / Insects / Invertebrates / Italy / Mites / Mites - physiology / Models, Biological / Multivariate Analysis / neutral model / niche / Organic matter / Oribatida / physiology / prediction / Sampling / Sarcoptiformes / Soil / soil animal community ecology / Soil ecology / Soil organic matter / Soil structure / Spatial analysis / spatial distribution / spatial patterns / spatial variations / Species Specificity / Stochastic models / Stochasticity / Sustainable communities / Synecology / variance