Contents lists available at ScienceDirect Biological Conservation journal homepage: www.elsevier.com/locate/biocon Assessment and prioritisation of plant species at risk from myrtle rust (Austropuccinia psidii) under current and future climates in Australia K. Berthon a, ⁎ , M. Esperon-Rodriguez a , L.J. Beaumont a , A.J. Carnegie b , M.R. Leishman a a Department of Biological Sciences, Macquarie University, North Ryde, Australia b NSW Department of Primary Industries, NSW Forest Science, Parramatta, Australia ARTICLE INFO Keywords: Invasive species Maxent Myrtaceae Pathogen Plant disease Species distribution models ABSTRACT Myrtle rust (Austropuccinia psidii) is an invasive rust fungus that attacks species of the Myrtaceae family, one of the most dominant plant families in Australia. The potential extent of myrtle rust affected areas and the high number of potential host species make a species prioritisation scheme essential to direct conservation and management efforts. This study builds on previous work by: compiling an up-to-date list of myrtle rust occur- rences and host species; mapping current and future climate suitability for myrtle rust; and identifying host species at risk based on range overlaps and susceptibility data. Suitable habitat for myrtle rust is restricted to eastern and southern coastal areas of Australia, with minor areas in the Northern Territory and Western Australia. This coastal distribution remains present under future climates, with some extension in inland New South Wales and Tasmania, and a reduction of suitable habitat in northern Queensland and Western Australia. Contrary to previous studies, our results indicate that south-west Western Australia has low climatic suitability for myrtle rust. Under current climate, 1285 Myrtaceae species are at risk of exposure to myrtle rust. This number decreases to 1224 species under future climate. We divide species exposed to myrtle rust into three priority categories, giving highest priority to species with at least 70% of their range overlapping regions climatically suitable for myrtle rust under current or future climates. We find 23 species are of high priority for conservation action. Finally, we provide a series of re- commendations for management of species within each priority category. 1. Introduction Austropuccinia psidii (formerly, Puccinia (Beenken, 2017), herein referred to as myrtle rust) is a pathogenic rust fungus native to Central and South America (Coutinho et al., 1998; Glen et al., 2007), that at- tacks a wide range of species of the Myrtaceae family (Carnegie and Lidbetter, 2012; Morin et al., 2012; Sandhu and Park, 2013; Giblin and Carnegie, 2014). Myrtle rust affects young growing tissues of plants, resulting in shoot dieback, reduced recruitment, and adult plant mor- tality in some species (Pegg et al., 2014; Carnegie et al., 2016). The fungus is a significant invasive pathogen globally, and in recent years has spread to the U.S.A (Uchida et al., 2006), South Africa (Roux et al., 2013), parts of Asia (Kawanishi et al., 2009; McTaggart et al., 2016) and the Pacific(Carnegie et al., 2010; Giblin, 2013), where it affects a range of horticultural, agricultural and native species (Glen et al., 2007). Australian vegetation is likely to be particularly vulnerable to myrtle rust due to the widespread dominance of Myrtaceous species. Myrtle rust was first detected in Australia in 2010 (Carnegie et al., 2010), and has since spread rapidly along the coast of New South Wales (NSW) and Queensland (Pegg et al., 2014; Carnegie et al., 2016), to Victoria (Agriculture Victoria, 2017), Tasmania (Biosecurity Tasmania, 2017) and, more recently, the Northern Territory (NT) (Westaway, 2016), and Lord Howe Island (Bob Makinson pers. comm. 2016). There are 2250 Myrtaceae species within Australia with many forming the dominant component of vegetation communities, such as the eucalypts (Eucalyptus, Angophora and Corymbia), paperbarks and bottlebrushes (Melaleuca and, formerly, Callistemon), and tea-trees (Leptospermum) (Makinson and Conn, 2014). Inoculation and field studies have con- firmed that there are at least 347 Australian hosts of myrtle rust, in- cluding species, subspecies and hybrids (Giblin and Carnegie, 2014). However, the majority of Myrtaceae species remain untested for myrtle rust susceptibility. Currently, detailed understanding of the impact of myrtle rust on native plant populations in Australia is confined to two highly suscep- tible rainforest species: Rhodomyrtus psidioides and Rhodamnia ru- bescens. Both of these species have suffered severe population declines due to myrtle rust infection (Carnegie et al., 2016), and as a https://doi.org/10.1016/j.biocon.2017.11.035 Received 21 May 2017; Received in revised form 16 November 2017; Accepted 28 November 2017 ⁎ Corresponding author at: Room 103 Building E8B, Macquarie University, Balaclava Road, North Ryde, NSW 2113, Australia. E-mail address: katherine.berthon@mq.edu.au (K. Berthon). Biological Conservation 218 (2018) 154–162 0006-3207/ © 2017 Elsevier Ltd. All rights reserved. T