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Tuesday, May 27, 2008 - 9:30 AM
151
Biodiversity loss and the functioning of aquatic ecosystems: The rivet hypothesis revisited
Bradley J. Cardinale, Ecology, Evolution & Marine Biology, University of California, Santa Barbara, Building 408, Room 216, Santa Barbara, CA 93106-9610
Most paradigms in ecology focus on biodiversity as a dependent variable – asking how it is maintained by community and ecosystem-level processes. Over the past two decades, a new paradigm has emerged in which researchers have asked how the diversity of genes, species, and functional groups can control, rather than just respond to, key processes like nutrient cycling, biomass production, and the dynamics of pests and disease. When this complementary line of research began, it was proposed that the functional role of species in an ecosystem is analogous to the role played by rivets on an airplane wing … you can lose some rivets without changing the functioning of the plane; but if you lose one rivet too many, you’ll find catastrophic impacts. Here I summarize studies that have experimentally manipulated diversity to revisit this analogy and ask – are there ‘thresholds’ of diversity loss beyond which ecological processes change dramatically? I show that the impact of species loss on nearly every ecological process is highly non-linear, but only some of these processes exhibit thresholds. The existence of thresholds cannot be predicted by how unique or redundant species are, but do appear to depend on how species interactions change across spatial and temporal scales. I end with thoughts on what future research is required to detect tipping points in ecological processes due to diversity loss.
Web Page: diversity, ecosystem function, thresholds