Print PageIdentifying species involved in consumer-resource interactions is one of the main limitations in the construction of complex food webs. DNA barcoding of gut profiles provides a valuable tool in characterizing trophic interactions. These new molecular tools using PCR libraries from gut contents can confirm consumer-resource pairings and test assumed linkages. The Moorea Biocode Project provides an ideal testing ground for documenting trophic linkages through the use of genetic signatures. Over the past four years, most macrobiotic species (>7000) on the French Polynesian tropical island have been digitized using DNA barcodes. We have successfully optimized molecular approaches using PCR libraries of DNA barcodes and blocking primers to analyze gut contents for any generalist predator. Our protocols have been tested in a variety of taxa including fishes, crustaceans, corals, lizards, rats and spiders.
Results/Conclusions
We can identify a large fraction (up to 95%) of prey items to species level using the Biocode reference library. While most species-level food webs can be reduced through assumed functional redundancy, we have found surprisingly little overlap in dietary composition among closely related species that would have been collapsed as equivalent trophic species in traditional food web analyses. Our results suggest functional redundancy in complex tropical ecosystems may be less than is currently assumed and that partitioning of trophic niches is more finely structured than previously supposed.
