Simple, Universal Rules Predict Trophic Interaction Strengths.

Area of Science:

• Ecology
• Evolutionary Biology
• Theoretical Ecology

Background:

• Ecological systems often display scaling relationships, but the underlying mechanisms, particularly for trophic interaction strengths, remain poorly understood.
• Trophic interaction strengths show scaling with predator and prey traits, yet lack clear evolutionary explanations.
• The predator functional response, describing feeding rate relative to prey density, is a key aspect of trophic interactions.

Purpose of the Study:

• To propose and test two fundamental rules explaining the scaling of predator functional responses.
• To provide an ultimate evolutionary explanation for the determinants of trophic interaction strengths.
• To link ecological constraints to the adaptive evolution of functional responses.

Main Methods:

• Formulated two rules based on predator energetic demands at low prey densities and maximal feeding rates at high prey densities.
• Derived equations from these rules to predict functional response parameters.
• Validated the model against over 2100 empirical functional response experiments.

Main Results:

• The proposed rules successfully predict functional response parameters across a large dataset of experiments.
• The model accurately predicts allometric scaling relationships within functional responses.
• The findings demonstrate that ecological constraints can shape the evolution of complex adaptive traits.

Conclusions:

• The two proposed rules offer a unifying framework for understanding trophic interaction strengths.
• Ecological realized constraints, rather than solely adaptive evolution, are critical determinants of functional response evolution.
• This work provides a potential ultimate explanation for the scaling of ecological interactions.