Download Population viability analysis (PVA)

Construction of nature
reserves
• Program WORLDMAP
Input data:
• Species diversity
• Cost of unit area
• Presence of other species, ……..
Measures of diversity
• Number of species
• Number of species from predefined
group (selective richness)
• Range centers
• Subtree length – phylogenetical
coverage
Measures of rarity
• Range size rarity – count species with
limited range
• Range centers
Spatial turnover
• Range edges
• Spatial heterogeneity
Construction of nature
reserves
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Hotspots
Complementarity areas
Minimizing costs
Comparison with random selection
Population viability analysis
(PVA)
What is PVA
• Analysis of all possible factors
affecting survival of a
species/population and assessment of
probability of recovery in a given time
period
What affects population
viability
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Demographic stochasticity
Environmental stochasticity
Catastrophes/Disturbances
Genetic processes
Parts of PVA
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Local population dynamics
Number of populations and spatial position
Population sizes
Carrying capacity
Frequency and effect of catastrophes
Effects of inbreeding
Migration
Occurrence of suitable unoccupied habitats
Types of models
• Precision of information
• Spatial and temporal scale
• Studied parameter (individual,
population…)
Precision of information
Information on local
population dynamics
• Complete population dynamics
• Only population growth rate and its
variations
Relationship to individual life span
Information on inbreeding
depression
• Sensitivity of the species
• Affected fitness components
• Relationship between degree of
inbreeding and fitness – shape of the
relationship
• Reproductive system
Other complicating factors
• Density dependence
• Source-sink dynamics
Density dependence
Density dependence
• Sources of density dependence
• Predation
• Researchers
Source-sink dynamics
Population size vs. local
population growth rate
Studied parameter
Types of models
• Individual-based – follow individuals
• Matrix-based – follow numbers of
individuals
• Models following gene flow
Spatial scale
• Single local population
• Regional scale
• Total range of species
Precision x possibility to
generalize
• Amount of information in the model
• Generality of the model
• Realism of the conclusions
Comparing results of PVA
• Sensitivity analysis
Sensibility of PVA
Quantitative predictions vs. summarization
of information
• Summarization of information on local
population dynamics
• Identification of types of endangerment
• Assessment of effect of endangerment
• Comparison of different scenarios
Reliability of predictions
Predictions of local dynamics
Capricorn
silvereye,
Zosterops
lateralis
chlorocephalus,
Brook & Kikkawa
1998
Reliability of predictions
Brook et al.
2000,
summary of
21 PVA’s
Reliability of predictions
Brook et al.
2000,
summary of
21 PVA’s
Threshold response
Territorial
mammal simulations,
Lande 1987
Threshold response
Pulliam
1992