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Dispersal Dynamics in Food Webs

Publikationsart Peer-reviewed
Publikationsform Originalbeitrag (peer-reviewed)
Publikationsdatum 2015
Projekt A theory for next-generation food web data
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Originalbeitrag (peer-reviewed)

Zeitschrift American Naturalist
Volume (Issue) 185(2)
Seite(n) 157 - 168
Titel der Proceedings American Naturalist
DOI 10.1086/679505

Abstract

Studies of food webs suggest that limited nonrandom dispersal can play an important role in structuring food webs. It is not clear, however, whether density-dependent dispersal fits empirical patterns of food webs better than density-independent dispersal. Here, we study a spatially distributed food web, using a series of population-dispersal models that contrast density-independent and density-dependent dispersal in landscapes where sampled sites are either homogeneously or heterogeneously distributed. These models are fitted to empirical data, allowing us to infer mechanisms that are consistent with the data. Our results show that models with density- dependent dispersal fit the a, b, and g tritrophic richness observed in empirical data best. Our results also show that density-dependent dispersal leads to a critical distance threshold beyond which site similarity (i.e., b tritrophic richness) starts to decrease much faster. Such a threshold can also be detected in the empirical data. In con- trast, models with density-independent dispersal do not predict such a threshold. Moreover, preferential dispersal from more centrally located sites to peripheral sites does not provide a better fit to em- pirical data when compared with symmetric dispersal between sites. Our results suggest that nonrandom dispersal in heterogeneous land- scapes is an important driver that shapes local and regional richness (i.e., a and g tritrophic richness, respectively) as well as the distance- decay relationship (i.e., b tritrophic richness) in food webs.
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