Individual variation and population dynamics: lessons from a simple system

Authored by T. G. Benton

Date Published: 2012-01-19

DOI: 10.1098/rstb.2011.0168

Sponsors: United Kingdom Natural Environment Research Council (NERC)

Platforms: R

Model Documentation: ODD Flow charts Mathematical description

Model Code URLs: Model code not found

Abstract

The mapping of environment, through variation in individuals' life histories, to dynamics can be complex and often poorly known. Consequently, it is not clear how important it is dynamically. To explore this, I incorporated lessons from an empirical system, a soil mite, into an individual-based model. Individuals compete for resource and allocate this according to eight `genetic' rules that specify investment in growth or reserves (which influences survival or fecundity), size at maturation and reproductive allocation. Density dependence, therefore, emerges from competition for food, limiting individual's growth and fecundity. We use this model to examine the role that genetic and phenotypically plastic variation plays in dynamics, by fixing phenotypes, by allowing phenotypes to vary plastically and by creating genetic variation between individuals. Variation, and how it arises, influences short- and long-run dynamics in a way comparable in magnitude with halving food supply. In particular, by switching variation on and off, it is possible to identify a range of processes necessary to capture the dynamics of the `full model'. Exercises like this can help identify key processes and parameters, but a concerted effort is needed across many different systems to search for shared understanding of both process and modelling.

Tags

Individual-based model Agent-based models Evolution Population dynamics phenotypic plasticity selection systems ecology context stochasticity Density-dependence Predictions Environmental variability Ecological dynamics Life-history traits Contemporary evolution Phenotypic plasticity