Multimodal distribution of transient time of predator extinction in a three-species food chain

TL;DR

This paper investigates the complex, multimodal distribution of predator extinction times in a three-species food chain, revealing inhomogeneity and anisotropy influenced by initial conditions and resource levels.

Contribution

It introduces new metrics to characterize the distribution of transient extinction times and explains their ecological significance from a dynamical systems perspective.

Findings

Distribution shows multimodal patterns near basin boundaries.

Inhomogeneity decreases with resource enrichment.

Anisotropy depends on the direction from the basin location.

Abstract

Studies of transient dynamics captures the time history of any dramatic changes in the dynamics of a system. The transient dynamics is investigated here in a classic ecological model of a bistable tri-trophic food chain. All the species in the food chain either coexist or undergoes a partial extinction with the loss of predator after a transient time that depends upon the initial density of species populations. The distribution of transient time of extinction of the predator in response to initial states shows interesting pattern of inhomogeneity and anisotropy in the basin of predator-fee state. Precisely, the distribution shows a multimodal character when the initial points are near the basin boundary, and unimodal at locations far from the border. The distribution is also anisotropic in the sense that the number of modes depends on the direction from the basin location. We define two new metrics, viz., homogeneity index and local isotropic index to characterize the distinctive features of the distribution. The inhomogeneity of distribution reduces significantly with resource enrichment, however, a similar change in anisotropy is relatively low. We try to explain the origin of such multimodal distributions from the dynamical system perspectives and present its ecological implications.