Resources alter the structure and increase stochasticity in bromeliad microfauna communities

Area of Science:

• Ecology
• Community Ecology
• Aquatic Ecology

Background:

• Community structure arises from joint stochastic and deterministic processes.
• The relative importance of these forces varies with environmental conditions and biological organization levels.
• Aquatic microfauna in tank bromeliads offer a model system to study these ecological dynamics.

Purpose of the Study:

• To investigate the influence of abiotic conditions, trophic interactions (bottom-up resources, top-down predators), and dispersal on microfauna community structure.
• To assess the interplay between deterministic and stochastic processes in community assembly.
• To determine the primary drivers of community structure in bromeliad ecosystems.

Main Methods:

• Field experiments in Costa Rican tank bromeliads manipulating resources, predators, and dispersal.
• Utilizing natural environmental gradients alongside experimental manipulations.
• Examining community structure at two spatial scales.

Main Results:

• Resource addition significantly increased microfauna abundance and decreased species richness, shifting community composition predictably.
• While functional groups responded to resources, species-level similarity decreased, indicating increased stochasticity in assembly.
• Predators and abiotic conditions had minimal impact on community structure.
• Dispersal limitation did not significantly affect community composition.

Conclusions:

• Bromeliad microfauna communities are predominantly controlled by bottom-up resource availability.
• Increased productivity can enhance the role of stochasticity in community assembly at the species level.
• The balance of deterministic and stochastic forces is context-dependent, varying with productivity and organizational scale.