Document: LIA-3-21-6

Weaving a tangled web: Complex interactions and metacommunity dynamics in Sarracenia purpurea pitchers.

COCHRAN-STAFIRA, L.*

Saint Xavier University, Chicago, IL 60655, U.S.A. ¹

Abstract:
The pitcher-like leaves of the carnivorous plant Sarracenia purpurea form natural microcosms in which a detritus-based aquatic food web composed of bacteria, protozoa, rotifers, insect larvae, and mites develops. Colonization of pitchers depends on oviposition by three species of commensal dipterans, water-, air- and debris-borne propagules, and phoresy of microorganisms by prey captured by the plant as well as by migrating midge larvae and mites. Field surveys of pitcher communities provide evidence that each pitcher contains a subset of the total species pool present in a particular S. purpurea habitat. Random sampling of individual pitcher communities reveals that protist and microinvertebrate diversity at any given moment in time tends to be low; however, experiments using enrichment cultures have shown that additional species are present either at undetectably low population densities or as dormant cysts or resting stages. Sequential sampling from pitchers over time shows that species composition, richness, and relative abundance patterns vary with time and nutrient accumulation. Data from experimental manipulations of food web components support the hypothesis that, following colonization, community structure within each pitcher is determined by strong direct and indirect effects stemming from interactions among species within and among trophic levels. I will discuss the roles of random colonization and species interactions in the maintaining metacommunity species richness and overall community stability.

Keywords: carnivorous plants, complex interactions, metacommunities, microcosms, Sarracenia purpurea

This abstract is being presented at: 11:35 AM in session:
Symposium # 19: Carnivorous Plants as Model Ecological Systems.