Trophic biogeography defines the interface between trophic ecology and biogeography, two fields that have historically been studied in isolation. Recent theory has begun to explicitly integrate trophic interactions into the Equilibrium Theory of Island Biogeography (ETIB), a model that has classically assumed species equivalence in their response to changes in island size and isolation. The theory of trophic biogeography predicts that predators and prey are likely to exhibit unique colonization-extinction rates (e.g., due differences in resource requirements, dispersal ability, and/or sensitivity to demographic stochasticity), and will therefore respond differentially to changes in patch size and isolation. To test these predictions I have combined (A) correlational studies examining the relationship between food web structure and habitat characteristics at the archipelago and ocean basin scale, with (B) local-scale manipulation of predators and habitat characteristics.
Coral and rocky reefs are model systems for studying trophic biogeography, because predation plays a critical role in recruitment dynamics, habitat are spatially heterogeneous, and both food web structure and habitat are dynamic due to a suite of impacts (e.g. cyclones, seastar outbreaks, bleaching, and overfishing). Understanding how changes in trophic interactions and habitat characteristics modify the structure and dynamics of the organisms that depend upon the reef is a key component of understanding spatio-temporal variation in coral reef communities. At the scale of the Society Islands archipelago and across islands in the South Pacific, I have shown that diversity varies widely and predictably with variation in habitat size and isolation; prey species diversity declines more rapidly on smaller and more isolated islands relative to predator diversity. At the local-scale, my work contrasts theoretical predictions of the interdependence of trophic interactions with habitat heterogeneity, although strong independent effects of both predation and habitat characteristics are present. For example our focal predator disproportionately consumed rare species (60% reduction) relative to common species (16% reduction), and reef fragmentation caused 50% increases in diversity. Collectively, this work demonstrates that patterns of biodiversity across heterogeneous habitat landscapes and at multiple spatial scales are dependent on trophic dynamics.
Stier A.C., and C.W. Osenberg. 2010. Propagule redirection: habitat availability affects colonization and recruitment in reef fishes Ecology 91:2826–2832. PDF.
Stier A.C., Kulbicki M.‡, and A.M. Hein. Biogeography Drives Marine Food Web Structure. Intended for Ecology Letters.
Stier A.C., K.M. Hanson, S.J. Holbrook, R.J. Schmitt, A.J. Brooks. Independent Effects of Predators and Habitat Availability on Community Organization of Reef Fishes. Submitted to Ecology