Community trait overdispersion due to trophic interactions: concerns for assembly process inference.

Area of Science:

• Ecology
• Community Ecology
• Theoretical Ecology

Background:

• Community assembly processes are often inferred from trait distributions, with overdispersion suggesting competition and clustering indicating habitat filtering.
• Previous studies have overlooked the impact of trophic interactions on these inferences, potentially leading to misinterpretations of community structure.
• Predation's role in species coexistence is theoretically established, but its quantitative effect on inferring assembly processes remains underexplored.

Purpose of the Study:

• To quantitatively demonstrate the influence of trophic interactions on inferring community assembly processes.
• To contrast trait dispersion and clustering in competitive communities with and without secondary consumers.
• To assess the reliability of trait distributions for inferring ecological processes when trophic interactions are present.

Main Methods:

• Utilized a trait-based ecological model to simulate the assembly of primary consumer communities.
• Compared trait dispersion and clustering patterns in simulated communities with and without the inclusion of trophic interactions (secondary consumers).
• Analyzed the impact of secondary consumer invasions and subsequent extinctions on trait distributions.

Main Results:

• Trophic interactions generally decreased trait clustering, leading to increased trait dispersion in competitive communities.
• This effect was driven by the invasion dynamics of secondary consumers and resulting competitor extinctions across the trait space.
• The magnitude and direction of these effects were influenced by specific model parameters and the choice of clustering metric.

Conclusions:

• Trophic interactions introduce significant complexity, challenging the inference of community assembly processes solely from trait distributions.
• Existing methods for inferring competition and habitat filtering may be unreliable when trophic interactions are prevalent.
• Future research should employ more process-based and inclusive ecological models for robust inference of community assembly.