Predators and priority effects suggested as potential drivers of microfauna communities in a community transplantation experiment along an elevational gradient

摘要

Transplantation experiments are a useful method to identify responses of organisms to environmental change. However, they are typically restricted to single or few species. Our experiment was carried out using entire bromeliad-inhabiting microfauna communities which were transplanted along an elevational gradient, simulating environmental change acting on the communities. Additionally, we manipulated trophic interactions, i.e. resource availability and predator presence, thus combining abiotic and biotic effects in a full-factorial experimental design. Using this experiment, we found a strong signal of original elevation in microfauna community structure (abundance, evenness, functional composition) with a shift from amoeba-dominated to flagellate-dominated communities with increasing original elevation. Surprisingly, the transplantation of communities along the elevational gradient did not affect community structure, indicating strong priority effects. Predation decreased microfauna abundance and increased microfauna evenness, specifically in higher original elevation and high resource levels. In summary, our results suggest that microfauna communities in bromeliads might be primarily shaped by priority effects and predator presence. However, interacting effects (between predator presence and resource availability, as well as between predator presence and original elevation) highlight the usefulness of studies with full-factorial experimental designs to understand community-structuring processes. Bromeliads and other micro-ecosystems provide convenient study systems for community level approaches that could be used in future studies concerning the effects of environmental change, for example climate change on community structure.