# Invasion controlled pattern formation in a generalized multi-species predator-prey system

## TL;DR

This paper explores complex pattern formations in a generalized multi-species predator-prey system, revealing five distinct phases driven by invasion probabilities and highlighting new dynamics beyond cyclic dominance.

## Contribution

It introduces a novel four-state predator-prey model with tunable peer invasion, uncovering rich pattern phases and transition points not previously studied in such systems.

## Key findings

- Five different pattern phases observed by varying invasion strength
- Transition points identified using autocorrelation, empty site fraction, and species variance
- Inner invasion rates can lead to species extinction under certain conditions

## Abstract

Rock-scissors-paper game, as the simplest model of intransitive relation between competing agents, is a frequently quoted model to explain the stable diversity of competitors in the race of surviving. When increasing the number of competitors we may face a novel situation because beside the mentioned unidirectional predator-prey-like dominance a balanced or peer relation can emerge between some competitors. By utilizing this possibility in the present work we generalize a four-state predator-prey type model where we establish two groups of species labeled by even and odd numbers. In particular, we introduce different invasion probabilities between and within these groups, which results in a tunable intensity of bidirectional invasion among peer species. Our study reveals an exceptional richness of pattern formations where five quantitatively different phases are observed by varying solely the strength of the mentioned inner invasion. The related transition points can be identified with the help of appropriate order parameters based on the spatial autocorrelation decay, on the fraction of empty sites, and on the variance of the species density. Furthermore, the application of diverse, alliance-specific inner invasion rates for different groups may result in the extinction of the pair of species where this inner invasion is moderate. These observations highlight that beyond the well-known and intensively studied cyclic dominance there is an additional source of complexity of pattern formation that has not been explored earlier.