Evaluating The Impact Of Species Specialisation On Ecological Network Robustness Using Analytic Methods

TL;DR

This paper introduces an analytic model to predict secondary extinctions in ecological networks, providing insights into network robustness and the effects of species specialization without relying on computational simulations.

Contribution

The authors develop a novel deterministic analytic model for predicting secondary extinctions, applicable to complex ecological networks and scenarios involving interaction strength loss.

Findings

Network robustness is maximized when secondary species degree variance is minimized.

Both specialization and generalization in interaction strength can enhance robustness depending on extinction scenarios.

The model accurately predicts secondary extinctions under random and targeted primary extinction scenarios.

Abstract

Ecological networks describe the interactions between different species, informing us of how they rely on one another for food, pollination and survival. If a species in an ecosystem is under threat of extinction, it can affect other species in the system and possibly result in their secondary extinction as well. Understanding how (primary) extinctions cause secondary extinctions on ecological networks has been considered previously using computational methods. However, these methods do not provide an explanation for the properties which make ecological networks robust, and can be computationally expensive. We develop a new analytic model for predicting secondary extinctions which requires no non-deterministic computational simulation. Our model can predict secondary extinctions when primary extinctions occur at random or due to some targeting based on the number of links per species or risk of extinction, and can be applied to an ecological network of any number of layers. Using our model, we consider how false positives and negatives in network data affect predictions for network robustness. We have also extended the model to predict scenarios in which secondary extinctions occur once species lose a certain percentage of interaction strength, and to model the loss of interactions as opposed to just species extinction. From our model, it is possible to derive new analytic results such as how ecological networks are most robust when secondary species degree variance is minimised. Additionally, we show that both specialisation and generalisation in distribution of interaction strength can be advantageous for network robustness, depending upon the extinction scenario being considered.