Intraspecific trait variation and its effects on food chains

Area of Science:

• Ecology
• Population Dynamics
• Food Web Theory

Background:

• Intraspecific variation in traits like foraging and anti-predator defense influences community dynamics.
• Tritrophic food chains with intermediate consumers exhibiting variation are key to understanding ecosystem stability.

Purpose of the Study:

• To explore the implications of intraspecific variation in a consumer population within a tritrophic food chain.
• To investigate the coexistence of two consumer phenotypes with trade-offs in foraging and anti-predator defense.

Main Methods:

• Modeling a diamond-shaped food web topology with two distinct consumer phenotypes.
• Analyzing the stability conditions and population dynamics under intraspecific variation.

Main Results:

• Unlike competing species, two consumer phenotypes within a single species can stably coexist due to switching between subpopulations.
• The presence of two stable phenotypes alters bottom-up and top-down effects, with predators impacting resources directly, not consumer subpopulations.
• Resource carrying capacity changes affect consumer subpopulations but not predator or resource populations.

Conclusions:

• Intraspecific variation can stabilize food chains by allowing for the coexistence of distinct phenotypes.
• This coexistence reshapes the traditional understanding of top-down and bottom-up ecological effects in food webs.