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Age- and density-dependent population dynamics in static and variable environments

Gurney, William and Nisbet, R.M. (1980) Age- and density-dependent population dynamics in static and variable environments. Theoretical Population Biology, 17 (3). pp. 321-344. ISSN 0040-5809

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Abstract

We consider a general model of a single-species population with age- and density-dependent per capita birth and death rates. In a static environment we show that if the per capita death rate is independent of age, then the local stability of any stationary state is guaranteed by the requirement that, in the region of the steady state, the density dependence of the birth rate should be negative and that of the death rate positive. In a variable environment we show that, provided the system is locally stable, small environmental fluctuations will give rise to small age structure and population fluctuations which are related to the driving environmental fluctuations by a simple “transfer function.” We illustrate our general theory by examining a model with a per capita death rate which is age and density independent and a per capita birth rate which is zero up to some threshold age a0, adopts a finite density-dependent value up to a maximum age ao + α, and is zero thereafter. We conclude from this model that resonance due specifically to single-species age-structure effects will only be of practical importance in populations whose members have a life cycle consisting of a long immature phase followed by a short burst of intense reproductive effort (α ⪡ ao).

Item type: Article
ID code: 41610
Keywords: death rates, local stability, birth rate, environmental fluctuations , Probabilities. Mathematical statistics, Ecology, Evolution, Behavior and Systematics
Subjects: Science > Mathematics > Probabilities. Mathematical statistics
Department: Faculty of Science > Mathematics and Statistics
Related URLs:
    Depositing user: Pure Administrator
    Date Deposited: 19 Oct 2012 18:59
    Last modified: 05 Sep 2014 18:22
    URI: http://strathprints.strath.ac.uk/id/eprint/41610

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