Population viability analysis (PVA)
9 important questions on Population viability analysis (PVA)
What is population viable analysis (PVA)?
What are the 3 most important aspects of the management of threatened species?
- Planning research and data collection
- Assessing vulnerability of populations/species
- Ranking management options
What are the most important rules in constructing a PVA?
- Not be too complex
- Based on reliable data
- Focus on what is known rather than what is guessed
- Higher grades + faster learning
- Never study anything twice
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What are deterministic models?
- When data is limited
- Comparisons of the general effectiveness of different management strategies for short time periods only
- By ignoring stochasticity these models paint a too pretty picture!!
What are stochastic models?
- Environmental stochasticity
- Demographic stochasticity, when population size is small
- Genetic stochasticity (genetic drift and inbreeding) when population size is small
- In small populations, chance effects can have a large impact and chance events cannot be predicted.
What are the 4 model forms? Name examples for each model type.
- Count- or census based models
- (annual population growth rate etc.) - Demographic models
- Age/life stage specific demographic rates (e.g. survival and reproduction) - Metapopulation and spatially structured models
- Collection of distinct populations linked by movement
- Prediction of population persistence - Individually based simulations
- Extrensive simulations to track the fates of individual animals
- Generally focuses on movement and location
What are the major outputs of the PVA?
- Growth rates
- Future population size
- Extinction risk
- Sensitivity analysis
What are the problems with PVA?
- PVAs are single species techniques
- PVAs leave out risk sources that are difficult to estimate or detect
- PVAs project long into the future when conditions are difficult to predict
- Lack of data is a major drawback in many cases
(garbage in = garbage out!!!)
What are the requirements for a successful long-term study?
- Interest from a dedicated researcher
- Money
- The ability to resist the periodic threat of rival ideologies and the administrators who sometimes evoke them
- Institutional support
The question on the page originate from the summary of the following study material:
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