Evaluating nestedness in a spatially structured detritus-based systems

Abstract

1 - Evaluating patterns and mechanisms behind species aggregation represents a fundamental issue in community and conservation ecology. 2 - The extent to which species colonize or disappear from habitats and resources is mostly related to several different factors, such as random processes of birth, death and migration, or complementarity in species responses to environmental disturbances, habitat heterogeneity or spatial distributions. 3 - Patterns of species aggregation can be evaluated by considering the network structure of such assemblages, where the use of ad-hoc null-models could help our understanding of the mechanisms underlying these structures. 4 - Here we evaluated the possible mechanisms underlying the nested assemblage of macroinvertebrates on leaf detritus in different sites of the transitional ecosystem of Tarquinia saltern, by using quantitative networks based on the abundances and frequencies of sampled taxa. 5 - Our results show that the use of quantitative information is able to closely mimic the pattern of incidence observed in the real network, with important outcomes for ecosystem’s functionality and its conservation.