Population Viability Analysis

Population Viability Analysis (PVA) is the estimation of a population’s extinction probability. PVA is commonly used to assess the viability of threatened species populations, but can also be used for non-threatened wildlife to determine and assess population management and manipulation.

PVA analyses demographic, environmental, catastrophic and genetic change in animal populations. In small and often fragmented threatened wild and captive populations, genetic drift and the consequent loss of genetic variation negatively impacts on demographic rates ( such as increased mortality and reduced fecundity) and increases the populations susceptibility to environmental variation, which is critical in climate change scenarios. Reduced genetic variation increases the probability of inbreeding which can lead to further population reduction. This in turn accelerates the loss of genetic variation, leading to further population decline. This negative feedback loop has been termed the “Extinction Vortex”.

We uses a sophisticated computer simulation model to undertake PVAs.

PVAs are a critical first step in understanding the complex demographic, genetic and environmental interactions occurring in wildlife populations. Typically a PVA model consists of a base scenario, the analysis of current data. Subsequent models explore the effects of a range of potential management scenarios that can affect the populations’ persistence and thus extinction probability.