Temporally auto-correlated predator attacks structure ecological communities

Area of Science:

• Ecology
• Population Dynamics
• Community Ecology

Background:

• The P* rule, proposed by Holt & Lawton, predicts competitive exclusion between prey species regulated by a shared predator.
• This rule is based on the prey species supporting the highest equilibrium predator density (P*).

Purpose of the Study:

• To re-examine the P* rule under conditions of temporal fluctuations in vital rates, specifically predator attack rates.
• To investigate how temporal auto-correlations in predator attack rates affect prey species coexistence and community dynamics.

Main Methods:

• The study theoretically re-examines the P* rule by incorporating temporal fluctuations and auto-correlations in vital rates.
• Mathematical modeling was used to analyze the impact of these fluctuations on predator-prey dynamics and prey vulnerability.

Main Results:

• When predator attack rates fluctuate without temporal auto-correlation, the P* rule holds.
• Positive auto-correlations in attack rates can lead to prey coexistence via a positive covariance between predator density and prey vulnerability.
• Negative or strongly positive auto-correlations can result in stochastic exclusion of one prey species.

Conclusions:

• Temporal auto-correlations in species interaction rates significantly influence ecological community structure and dynamics.
• The P* rule's applicability is limited when temporal dynamics and auto-correlations in predator-prey interactions are considered.
• Novel coexistence mechanisms, such as those arising from predator-prey covariance, can emerge under fluctuating conditions.