Allometric Constraints to Food Webs within a Metacommunity Context

Advancing in the connection between global change and communities structure and function has become a pressing issue. Food web and body size structure of communities are interrelated by the trophic position-body size relationship (TP-M). While gape limitation promotes a positive relationship, energetic constrain force a negative one, mutually determining a hypothetic humped TP-M association. Here, we explicitly modeled the effect of community isolation and the mass-dependent individual movement on the TP-M relationship. Our result indicates that in spite of their greater abilities to move among communities, larger species could be particularly sensible to ecosystem fragmentation. The analysis of alternative metacommunity networks congruently points to larger constraints to trophic positions and species viability, among larger species inhabiting isolated communities. Different components of global change mutually reinforce to impact larger species at higher trophic position. This impact could reduce or enhance the interaction between large-size species and species with lower body size; determining not evident changes in community structure. The body size and food web structure of communities are particularly sensible to global change. The analysis of allometric trends in energy demands, resource acquisition, and movement abilities, provides testable predictions about the association between food web structure and global change.