Individual variability and population regulation: a model of the significance of within-generation density dependence
Authored by Volker Grimm, J Uchmanski
Date Published: 2002
DOI: 10.1007/s00442-002-0875-y
Sponsors:
European Union
Platforms:
No platforms listed
Model Documentation:
Other Narrative
Mathematical description
Model Code URLs:
Model code not found
Abstract
Most models of theoretical population ecology consider population
density as a state variable and thus ignore the fact that populations
are composed not of identical average individuals but of individuals
which are usually different. However, this individual variability may be
important for population regulation. We therefore analysed an
individual-based population model which explicitly describes
within-generation processes, i.e. individual growth, starvation, and
resource dynamics. The results show that if population dynamics a-re
dominated by slow changes in resource level, the population size in the
model undergoes wide oscillation, often leading to extinction. If, on
the other hand, fast within-generation processes predominate, such as
starvation and sudden drops in resource levels, the population
fluctuates to a limited extent around an average. Within-generation
density dependence may thus be an important mechanism which is largely
ignored in classic time-discrete state-variable models. We conclude that
the individual-based approach provides important insights into the
hierarchical organization of population dynamics, i.e. the relationship
between fast processes at the individual level and slower processes at
the population level.
Tags
Dynamics
stability
Persistence
Ecological paradigms