Print PageWhat factors drive the observed changes in the number of coexisting species across different spatial and temporal scales? This is a fundamental, albeit vexing, question in ecology. Most answers to this question emphasize the role of abiotic factors (e.g., area, temperature, energy) as drivers of diversity patterns. However, empirical and theoretical evidence suggest that biodiversity; biotic factors such as species interactions or biological heterogeneity, could regulate diversity itself within and across communities. This regulation can be either direct, through species interactions, or indirect due to modulation of abiotic factors by the organisms. Here we perform a meta-analysis to test the hypothesis that biodiversity drives diversity patterns by: (1) quantifying the relative importance of abiotic vs. biotic drivers on species diversity patterns and (2) quantifying how the relative importance of these drivers varies across scales, organismal type and ecosystems. To address these objectives we first identified all proposed biotic and abiotic drivers and hypotheses reported in the literature to account for patterns in diversity. We used these as a template to classify a set of 307 papers compiled by Field et al (2009) and then created the dataset used in the meta analyses.
Results/Conclusions
Initial results from our meta-analysis indicate that both abiotic and biotic drivers may positively influence diversity, but the effect size of biotic drivers is significantly larger. Our results show that this difference is the result of biotic drivers having a larger and significant effect in animal consumers than in producers, in continental than in island settings, in terrestrial than in freshwater or marine ecosystems, at large spatial extents ranging from 100-1000 km2, and in the context of hypotheses dealing with historical processes. Although the biotic factors analyzed in our study do not capture all possible aspects of biodiversity, we offer strong evidence in support of the hypothesis that biodiversity is a strong driver of diversity. Noteworthy, biotic factors appeared to be stronger than abiotic ones, especially in terrestrial environments and for consumer organisms at large spatial scales. We discuss the mechanisms behind these patterns
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