Emergent Diversity in an Open-Ended Evolving Virtual Community

Abstract

A version of this paper with color figures is available online at http://dx.doi.org/10.1162/ artl_a_00059. Subscription required.Abstract Understanding the dynamics of biodiversity has become an important line of research in theoretical ecology and, in particular, conservation biology. However, studying the evolution of ecological communities under traditional modeling approaches based on differential calculus requires speciesʼ characteristics to be predefined, which limits the generality of the results. An alternative but less standardized methodology relies on intensive computer simulation of evolving communities made of simple, explicitly described individuals. We study here the formation, evolution, and diversity dynamics of a community of virtual plants with a novel individual-centered model involving three different scales: the genetic, the developmental, and the physiological scales. It constitutes an original attempt at combining development, evolution, and population dynamics (based on multi-agent interactions) into one comprehensive, yet simple model. In this world, we observe that our simulated plants evolve increasingly elaborate canopies, which are capable of intercepting ever greater amounts of light. Generated morphologies vary from the simplest one-branch structure of promoter plants to a complex arborization of several hundred thousand branches in highly evolved variants. On the population scale, the heterogeneous spatial structuration of the plant community at each generation depends solely on the evolution of its component plants. Using this virtual data, the morphologies and the dynamics of diversity production were analyzed by various statistical methods, based on genotypic and phenotypic distance metrics. The results demonstrate that diversity can spontaneously emerge in a community of mutually interacting individuals under the influence of specific environmental conditions.

Revisiting Van Valen's Red Queen Hypothesis

“…The diverse theoretical developments of Van Valen's picture have flourished in many directions, including (a) the early game theoretic models [51] , (b) predator-prey and host-parasite evolution [30,32,36,43,55], (c) microbiota dynamics [10], (d) the evolution of plant shapes in a virtual environment [24,26], (e) coevolution of robots [40] and (f) dynamical complexity in economics [3,45]. It also inspired a new generation of statistical physics models of evolution [20,38].…”

Defining and simulating open-ended novelty: requirements, guidelines, and challenges

“…This definition of OE is due to the seminal work of Bedau [15,19,20], illustrated in an ecological model of L-system plants [38] where evolution is deemed "without a definite maximum fitness, hence no optimal goal or solution to reach", or in abstract heterogenous cellular automata [77], where it is qualified as "long-term". It is close to (i), but complemented by statistical measures to characterize long-term evolutionary dynamics and distinguishes between three classes of evolutionary systems, including a test for OE.…”

Artificial Neurogenesis: An Introduction and Selective Review

“…A generally desirable trait is that small changes in a representation should lead to small changes in the phenotype-a "gentle slope" allowing for incremental search techniques. In AD systems, however, due to the nonlinear dynamic properties of the transformation process, it is not unusual for small genetic changes to have large effects on the phenotype [87].…”

“…Despite this, the use of environmentally induced plasticity in AD systems is rare. Only a few examples have shown that environmental cues can be used to reproduce plasticity effects commonly seen in natural phenomena, such as: virtual plant growth [87,252], circuit design [280], or other scenarios [157,190]. In one case, Kowaliw et al experimented with the growth of planar trusses, a model of structural engineering.…”