Network properties, species abundance and evolution in a model of evolutionary ecology

TL;DR

This paper investigates how network properties evolve in ecological models, revealing that high connectivity leads to interconnected species networks and influences species abundance, with implications for understanding real ecosystems.

Contribution

It demonstrates how network connectivity affects the formation of interconnected species clusters and the realism of species abundance distributions in ecological models.

Findings

High connectivity results in a single large interconnected network.

Species abundance is realistic only at high connectivity levels.

Interaction strength distributions change over time, but the number of links remains stable.

Abstract

We study the evolution of the network properties of a populated network embedded in a genotype space characterised by either a low or a high number of potential links, with particular emphasis on the connectivity and clustering. Evolution produces two distinct types of network. When a specific genotype is only able to influence a few other genotypes, the ecology consists of separate non-interacting clusters in genotype space. When different types may influence a large number of other sites, the network becomes one large interconnected cluster. The distribution of interaction strengths -- but not the number of connections -- changes significantly with time. We find that the species abundance is only realistic for a high level of species connectivity. This suggests that real ecosystems form one interconnected whole in which selection leads to stronger interactions between the different types. Analogies with niche and neutral theory are also considered.