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Reliability of relative predictions in population viability analysis.
MCCARTHY, MICHAEL1,2, ANDELMAN, SANDY2, POSSINGHAM, HUGH2,3, 1 2 3
ABSTRACT- Recent work has demonstrated the uncertainty associated with predicting risks of extinction, drawing into question the usefulness of population viability analysis (PVA). However, the most valuable role of PVA is the ability to predict relative risks. Therefore, a stochastic Ricker model was used to investigate the reliability of predicted changes in risks of decline in response to changes in parameters, the reliability of ranking species in terms of their relative threat, and the reliability of choosing the better of two management decisions. The predicted changes in risks of decline were more reliable than absolute predictions. Across 160 different parameter combinations, the rank correlation between the true risks of extinction and predicted risks was 0.59 when using 10 years of data, increasing to 0.89 when using 100 years of data. Finally, the better of two management strategies was identified 67-74% of the time using 10 years of data, increasing to 92-93% of the time when using 100 years of data. The results demonstrate that despite uncertainty in the predicted risks of decline, PVA may reliably contribute to management of threatened species.
KEY WORDS: extinction risk, management decision, population viability analysis, risk assessment