DOI: 10.1101/485946Dec 4, 2018Paper

The shape of density dependence and the relationship between population growth, intraspecific competition and equilibrium population density

BioRxiv : the Preprint Server for Biology
Emanuel A. FronhoferFlorian Altermatt

Abstract

Many ecologists and evolutionary biologists use the logistic growth model to capture density dependence. However, assumptions and limitations of this popular model are not well appreciated. Here, we derive population growth models from underlying consumer-resource dynamics and show that the logistic is likely not applicable to many biological systems. We first validate that filter feeders (type I functional response) using abiotic resources generally follow a convex density-regulation function, fully described by the continuous-time Beverton-Holt model. Furthermore, we show that saturating consumers (type II functional response) exhibit density-regulation functions that can switch from concave to convex. We derive a density-regulation function for saturating feeders on abiotic resources and show that more complex consumer dynamics can be well approximated with a continuous-time Maynard Smith-Slatkin model. Importantly, we show how population level parameters, such as intrinsic rates of increase and equilibrium population densities are not independent, but are functions of the same underlying parameters. Our work highlights that the commonly assumed positive relationship between equilibrium population density and competitive abi...Continue Reading

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