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Individuals do count! Individual variability and stochastic population dynamics
Applied Math| Speaker: | Bruce Kendall, Donald Bren School for the Environment, UC Santa Barbara |
| Location: | 693 Kerr |
| Start time: | Fri, Mar 15 2002, 4:10PM |
Description
Population viability analysis (PVA) is a technique that employs stochastic
demographic models to predict extinction risk. All else being equal, higher
variance in a demographic rate leads to a greater extinction risk.
"Demographic stochasticity" represents variance due to differences among
individuals. Current implementations of PVAs, however, assume that the
expected fates of all individuals are identical. For example, demographic
stochasticity in survival is modeled as a random draw from a binomial
distribution. Together with Gordon Fox (University of South Florida), I have
found that variation among individuals results in a change in the
population-level demographic variance. I will demonstrate these results both
qualitatively and quantitatively, and show that individual variability may
often act to reduce the population-level demographic variance (thus
increasing the long-term population growth rate and reducing the risk of
extinction).
The first paper on this stuff just came out in the Feb. Conservation
Biology, if anyone wants a preview.
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