Evolutionary food web model based on body masses gives realistic networks with permanent species turnover

Abstract

The networks of predator-prey interactions in ecological systems are remarkably complex, but nevertheless surprisingly stable in terms of long term persistence of the system as a whole. In order to understand the mechanism driving the complexity and stability of such food webs, we developed an eco-evolutionary model in which new species emerge as modifications of existing ones and dynamic ecological interactions determine which species are viable. The food-web structure thereby emerges from the dynamical interplay between speciation and trophic interactions. The proposed model is less abstract than earlier evolutionary food web models in the sense that all three evolving traits have a clear biological meaning, namely the average body mass of the individuals, the preferred prey body mass, and the width of their potential prey body mass spectrum. We observed networks with a wide range of sizes and structures and high similarity to natural food webs. The model networks exhibit a continuous species turnover, but massive extinction waves that affect more than 50% of the network are not observed.

The role of biotic forces in driving macroevolution: beyond the Red Queen

“…For instance, they show that in the absence of extrinsic forcing, biotic interactions can create coevolutionary trait dynamics in which the number of species fluctuates widely in a periodic or chaotic fashion [36]. Biotically driven mass extinctions or extinction cascades are also demonstrated in these models [36,39,43]. Takahashi et al's [39] model features food webs that alternate between two community states: they repeatedly build up and evolve towards a quasi-stable state that is very vulnerable to perturbation, where demographic stochasticity triggers an extinction cascade, starting the cycle again.…”

“…The last decade has seen a series of important theoretical papers that explore evolving food webs and their nonequilibrium dynamics [36][37][38][39]43]. These papers make no reference to the Red Queen.…”

A new dimension: Evolutionary food web dynamics in two dimensional trait space

“…Nonetheless, we expect our results to be relatively gen-180 eral, since cannibalism can be described by an additional contribution to the 181 intra-specific competition strength; this would slightly decrease the biomass 182 of the cannibalistic morph [5], but the general evolutionary outcome would 183 not be affected. This is confirmed by numerical investigations which showed…”

“…We have proposed a framework for evolutionary food webs that extends 528 previous models [40,11,5,31] by considering a second niche-space dimension.…”

Evolutionary food web models: effects of an additional resource

“…Several extensions of the original model have been used to study different aspects of food web assembly. This includes the introduction of i) different feeding ranges and feeding centres for each species to investigate the mechanism determining food web structure and to reproduce the variety of food web structures that is observed in empirical data, (Ingram et al, 2009;Allhoff et al, 2015), ii) an additional trait axis to study the spatial influence on food web assembly (Ritterskamp et al, 2016b); and iii) gradual evolutionary change to study diversification (Brännström et al, 2011). However, we are not aware of any allometric, evolutionary food web model that considers multiple resources.…”