Consumer trait variation influences tritrophic interactions in salt marsh communities

Area of Science:

• Ecology
• Evolutionary Biology
• Marine Biology

Background:

• Intraspecific variation is crucial for understanding ecological and evolutionary processes.
• Host plant-associated trait variation in consumers can mediate trophic dynamics.
• Consumer variation plays a key role in tritrophic food webs and trophic cascades.

Purpose of the Study:

• To document intraspecific trait variation in the marsh periwinkle (Littoraria irrorata) based on host plant species.
• To examine the effects of this consumer trait variation on a salt marsh tritrophic food web.
• To understand how consumer differences influence plant community structure and dynamics.

Main Methods:

• Field surveys and laboratory experiments were used to document trait variation in Littoraria irrorata.
• A 12-week mesocosm experiment investigated the impact of consumer trait variation on plant communities.
• The study analyzed morphological and behavioral traits of Littoraria from different host plants (Spartina alterniflora and Juncus roemerianus).

Main Results:

• Littoraria irrorata exhibited significant morphological and behavioral trait variation based on host plant species.
• Consumer trait differences interacted with plant composition and predator presence to affect plant height, density, and biomass.
• These trait differences significantly altered the tritrophic marsh food web dynamics over seasonal timescales.

Conclusions:

• Intraspecific trait variation in consumers has substantial ecological consequences for food web structure and dynamics.
• Consumer trait differences can modulate trophic cascades, influencing plant community composition.
• Phenotypic plasticity or genetic differences in consumers can lead to feedbacks that influence future trait divergence.