Determining the functional form of density dependence: deductive approaches for consumer-resource systems having a...

Area of Science:

• Ecology
• Population Dynamics
• Theoretical Biology

Background:

• Consumer-resource models are crucial for understanding population dynamics.
• Density dependence, how population size affects birth/death rates, is key to ecological stability.
• Existing models like the theta-logistic may oversimplify consumer density dependence.

Purpose of the Study:

• To propose a general method for determining the functional form of consumer density dependence.
• To explore how consumer mortality rates influence equilibrium population sizes.
• To investigate the inheritance of density dependence characteristics from resources to consumers.

Main Methods:

• Analyzing equilibrium population sizes across various harvest (mortality) rates.
• Utilizing several one-consumer/one-resource models.
• Examining the relationship between consumer mortality and its equilibrium population size.

Main Results:

• Consumer density dependence often exhibits both concave and convex segments, a feature absent in the theta-logistic model.
• Resource density dependence and response shapes are frequently inherited by the consumer.
• Predicted consumer population size shows a non-monotonic response to mortality, declining at low and high rates but remaining stable or increasing at intermediate rates.

Conclusions:

• Consumer-resource models provide a more realistic depiction of density dependence than simpler models.
• The complex density dependence has significant implications for managing and conserving natural populations.
• Understanding these dynamics is vital for effective ecological management and policy.