On studying keystone species complexes and perspectives of possible applications in conservation biology
Abstract
Advanced techniques of network analysis enable the quantification of indirect interactions and topological importance of components in ecosystems. Based on both field results and models, indirect effects are of high interest in ecological systems. Our aim was to determine the positionally most important set of n nodes in a network, to analyse whether a set of nodes for small n is a subset of another for larger n, and to quantify this nestedness. We applied a network analytical tool, i.e. the KeyPlayer analysis. We defined topological keystone species complexes, illustrated the use of this method on a case study and analysed a database of 22 plant-pollinator interaction networks. Since there is a strong need for multispecies, functional conservation biology, our network context and this tool may be of high future interest. Our main conclusion is that it is not the complexity (species richness, connectance) but the actual topology (asymmetry of plants and pollinators) of these systems what determines patterns of keystone species and poses structural constraints on the possible success of conservation practice. Our results suggest that structural constraints are stronger on more asymmetrical interaction networks.
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