Analysis of nematode trophic structure in agroecosystems: Functional groups versus high resolution taxonomy

Abstract

Analyses of nematode community trophic structure can be made at different levels of taxonomic resolution depending on the type of ecological question being asked. We compared two methods of identifying fungivore, bacterivore, herbivore and omnivore/predator trophic groups of a nematode community in a corn agroecosystem. With the functional group approach we used gross esophageal morphology as the primary indicator of trophic status. With the high resolution taxonomy approach we identified nematodes to genus to determine trophic classification. We found that the higher resolution taxonomic approach did not improve the trophic classifications that were based on gross morphology. We suggest that the functional group approach can be used successfully to investigate soil food web structure and function because of the larger number of samples that can be processed in both time and space, and because highly specialized taxonomic training is not required. This approach will be sufficient in many ecosystem-level studies where the majority of nematodes fall into easily recognizable groups. High resolution taxonomy is best suited to address questions concerning biodiversity.