How to decide whether to move species threatened by climate change.

Tracy M Rout,Tara G Martin,Hugh P Possingham,Nicola J Mitchell,Doug P Armstrong,Eve Mcdonald-Madden,Zoe G Davies

doi:10.1371/journal.pone.0075814

Abstract

Introducing species to areas outside their historical range to secure their future under climate change is a controversial strategy for preventing extinction. While the debate over the wisdom of this strategy continues, such introductions are already taking place. Previous frameworks for analysing the decision to introduce have lacked a quantifiable management objective and mathematically rigorous problem formulation. Here we develop the first rigorous quantitative framework for deciding whether or not a particular introduction should go ahead, which species to prioritize for introduction, and where and how to introduce them. It can also be used to compare introduction with alternative management actions, and to prioritise questions for future research. We apply the framework to a case study of tuatara (Sphenodon punctatus) in New Zealand. While simple and accessible, this framework can accommodate uncertainty in predictions and values. It provides essential support for the existing IUCN guidelines by presenting a quantitative process for better decision-making about conservation introductions.

Highlights

Introducing individuals of a species to locations where the climate is predicted to be suitable in the future, but where the species has never occurred before, is a controversial adaptation action for combating the predicted impacts of climate change on biodiversity [1,2,3,4,5,6,7]
This framework is targeted towards a single decision-maker, for example, a government agency or non-governmental conservation organisation, whose aim is to save species from extinction and who has identified one or more species likely to go extinct in their current range as it becomes unsuitable due to climate change, and for which an introduction outside their historical range is a possible option
We have focused here on conservation introductions in response to climate change, which are only a subset of cases where a species is introduced to an area outside of its historical range for conservation purposes

Summary

Introduction

Introducing individuals of a species to locations where the climate is predicted to be suitable in the future, but where the species has never occurred before, is a controversial adaptation action for combating the predicted impacts of climate change on biodiversity [1,2,3,4,5,6,7] This action is a type of conservation introduction [8], and has been referred to as ‘managed relocation’, ‘assisted migration’ or ‘assisted colonization’ in recent debate about its implementation [3]. There are a number of critical decisions faced by those considering introductions as a potential climate adaptation strategy, and it is imperative that these decisions are aided by explicit, transparent and mathematically rigorous decision-making frameworks [11] While such a framework has been used to determine the optimal timing of introductions motivated by climate change [12], several other key management questions remain unanswered. Two recent studies [1,2] develop frameworks for addressing this question, but neither do so within the tenets of decision science: both lack a quantifiable management objective and mathematically rigorous problem formulation

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Results

Conclusion