The Structure of Ecological Networks

Ecological networks describe species interactions in ecological processes. There is a growing number of methods for describing and analysing the interaction patterns between species in these networks. The most commonly used network-level indices, such as connectance, degree distribution, nestedness, and modularity, describe the diversity and organization of species interactions within the entire network. These indices can provide insight into the rules underlying the organization of ecological processes, but also about the robustness of ecological networks to changes and perturbations. Species-level indices, such as centrality, dependence, species strength, module roles, and different indices for species specialization, describe the roles of species in the network and the importance of species, both for their direct interaction partners and for the cohesion of the entire network. These indices can be used to identify species with important roles which is useful for the conservation of ecological processes. Both network-level and species-level indices are influenced by various factors, such as species’ local abundances, traits, and phylogenetic relationships, as well as environmental conditions.