How Does the Evolution of Universal Ecological Traits Affect Population Size? Lessons from Simple Models.

Area of Science:

• Ecology
• Evolutionary Biology
• Population Dynamics

Background:

• Consumer-resource models are crucial for understanding population dynamics.
• Adaptive evolutionary change is typically assumed to benefit populations.

Purpose of the Study:

• To investigate the impact of adaptive evolutionary change on consumer population size.
• To analyze how changes in ecological parameters (attack rate, conversion efficiency, mortality) influence population dynamics.

Main Methods:

• Analysis of multiple consumer-resource models.
• Examination of two scenarios: perturbed equilibrium and genetic perturbation.
• Modeling evolutionary changes in consumer traits affecting key ecological parameters.

Main Results:

• Adaptive evolutionary change can frequently lead to a decrease in consumer population size (adaptive decline).
• Adaptive decline occurred in up to 50% of cases when evolutionary equilibrium was perturbed.
• Adaptive decline can occur even with fitness-increasing genetic changes, particularly with overexploited resources and increased attack rates.

Conclusions:

• Adaptive evolution in consumers can paradoxically result in population decline.
• Consumer traits influencing attack rate, conversion efficiency, and mortality can all drive adaptive decline.
• Environmental changes mimicking adaptive evolution can also cause counterintuitive population effects.