Forecasting endangerment and extinction

The International Union for Conservation of Nature (IUCN) publishes a regularly updated Red List of threatened species. Many analyses use these data to characterise biodiversity, make predictions, and inform conservation. For example, the EDGE of Existence programme run by the Zoological Society of London (ZSL) that supports the conservation of species that are Evolutionarily Distinct and Globally Endangered (EDGE); the latter of these criteria is based on the IUCN Red List. An essential component of such analyses is mapping from IUCN Red List categories to probabilities of extinction within a range of timescales. Currently these mappings are based on extrapolation from limited quantitative guidelines given by IUCN. The accuracy of this approach is questionable, and there is no envelope of uncertainty around these predicted values. The purpose of this project is to apply a range of quantitative techniques to IUCN data in order to improve mappings to probability of extinction for species. This will lead to new methods for conservation prioritisation and for predicting future extinctions. Work Package 1: Markov models. The project will involve developing a Markov model to characterise the probabilities of transitioning between Red List categories. This model will be parameterised from historic IUCN data. Key components will be i) incorporation of hidden states to take into account the possibility for errors in category placement, ii) splitting of categories into smaller units based on subsidiary Red List information such as the criteria of assessment, area of occupancy and population stability, iii) sensitivity analyses and power calculations to check robustness and measure uncertainty in the results iv) testing of the method with a reserved portion of the training data set, including investigating effects of sampling bias. Work Package 2: Forecasting extinction by taxa and region. Model findings will be separated according to taxonomic group, region, and habitat. This will enable testing to determine whether there is a bias in transition probabilities depending on any of these factors. Furthermore, application of the probabilities of extinction derived from the Markov model to IUCN Red List categories of species will give extinction forecasts. These results can be compared across different taxa, regions, and habitats. Probabilities of extinction will also enable biodiversity indices such as the Red List Index to be predicted into the future. Work Package 3: Applications to conservation prioritisation. The EDGE of existence programme incorporates evolutionary data with IUCN data to prioritise conservation work. A key question related to the use of probabilities of extinction in this context is what time scale to base the probabilities of extinction on, are we making decisions based on minimising diversity loss 50 years in the future, 100 years, or some other time? The project will address this question in two ways: i) by using a discount rate (from economic theory) to value future diversity ii) by simulating conservation work on the system (in the form of reducing probabilities of extinction) and measuring the outcomes as a function of the time horizon used for decision making