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Stochastic demography and population dynamics in the red kangaroo Macropus rufus
Article first published online: 6 AUG 2009
DOI: 10.1111/j.1365-2656.2009.01601.x
© 2009 The Authors. Journal compilation © 2009 British Ecological Society
Additional Information
How to Cite
Jonzén, N., Pople, T., Knape, J. and Sköld, M. (2010), Stochastic demography and population dynamics in the red kangaroo Macropus rufus. Journal of Animal Ecology, 79: 109–116. doi: 10.1111/j.1365-2656.2009.01601.x
Publication History
- Issue published online: 11 DEC 2009
- Article first published online: 6 AUG 2009
- Received 19 March 2009; accepted 3 July 2009 Handling Editor: Tim Benton
Keywords:
- climate;
- elasticity;
- mammals;
- matrix models
Summary
1. Many organisms inhabit strongly fluctuating environments but their demography and population dynamics are often analysed using deterministic models and elasticity analysis, where elasticity is defined as the proportional change in population growth rate caused by a proportional change in a vital rate. Deterministic analyses may not necessarily be informative because large variation in a vital rate with a small deterministic elasticity may affect the population growth rate more than a small change in a less variable vital rate having high deterministic elasticity.
2. We analyse a stochastic environment model of the red kangaroo (Macropus rufus), a species inhabiting an environment characterized by unpredictable and highly variable rainfall, and calculate the elasticity of the stochastic growth rate with respect to the mean and variability in vital rates.
3. Juvenile survival is the most variable vital rate but a proportional change in the mean adult survival rate has a much stronger effect on the stochastic growth rate.
4. Even if changes in average rainfall have a larger impact on population growth rate, increased variability in rainfall may still be important also in long-lived species. The elasticity with respect to the standard deviation of rainfall is comparable to the mean elasticities of all vital rates but the survival in age class 3 because increased variation in rainfall affects both the mean and variability of vital rates.
5. Red kangaroos are harvested and, under the current rainfall pattern, an annual harvest fraction of c. 20% would yield a stochastic growth rate about unity. However, if average rainfall drops by more than c. 10%, any level of harvesting may be unsustainable, emphasizing the need for integrating climate change predictions in population management and increase our understanding of how environmental stochasticity translates into population growth rate.