Combining population genetics, species distribution modelling and field assessments to understand a species vulnerability to climate change KIMBERLY P. MCALLUM, 1 GREG R. GUERIN, 1 MARTIN F. BREED 1 AND ANDREW J. LOWE 1,2 * 1 Australian Centre for Evolutionary Biology and Biodiversity, Environment Institute, School of Earth and Environmental Sciences, University of Adelaide, Adelaide, SA 5005, Australia (Email: andrew.lowe@adelaide.edu.au), and 2 Department of Environment, Water and Natural Resources, Adelaide, South Australia, Australia Abstract Climate change is recognized as a major threat to biodiversity. Multidisciplinary approaches that combine population genetics and species distribution modelling to assess these threats and recommend conserva- tion actions are critical but rare. Combined, these methods provide independent verification and a more compelling case for developing conservation actions. This study integrates these data streams together with field assessments and spatial analyses to develop future genetic resource management recommendations. The study species was Callistemon teretifolius (Needle Bottlebrush), a shrub species endemic to the Mount Lofty and Flinders Ranges, South Australia, and potentially vulnerable to climate change. Chloroplast microsatellite and Amplified Fragment Length Polymorphism data were combined with species distribution modelling (MaxEnt), spatial analysis and field assessment to evaluate climate change vulnerability.Two major genetic groups were identified (Mount Lofty and Flinders Ranges). Populations in the Flinders Ranges, especially the Southern Flinders Ranges exhibited the highest genetic diversity, indicating a possible genetic refugium. Lower genetic diversity to the south in the Mount Lofty Ranges and north in the Gammon Ranges may be due to post-glacial expansion into these areas from the Flinders Ranges or loss of alleles. Low levels of contemporary gene flow were identified, which suggests Callistemon teretifolius may have a limited capacity to respond to climate change through migration. Range restrictions were predicted for all future climates, especially in the north. It is likely that C. teretifolius will be adversely affected by climate change, due to limited gene flow, predicted range restriction and loss of suitable habitat. The Southern Flinders Ranges should be a priority for conservation because it contains the highest number of individuals and genetic diversity. We recommend monitoring and adaptive management involving restoration in the Southern Flinders Ranges, potentially incorporating genetic translocations from other areas to capture diversity, to assist C. teretifolius to adapt to climate change. Key words: climate change, conservation genetics, local endemic, range contraction, refugium, species distribu- tion modelling. INTRODUCTION Temperature and rainfall redistribution as a result of contemporary climate change are expected to impose serious challenges on many plant species (Davis & Shaw 2001; Parmesan 2006). A species ability to respond to climate change through migration or in situ adaptation governs its extinction risk (Walther et al. 2002; Hughes 2003; Travis 2003; Aitken et al. 2008). Species at greatest risk are likely to be those that are range-restricted or occur at the highest available alti- tude (Thuiller et al. 2005; Parmesan 2006; Willi et al. 2006). These species tend to have limited dispersal capacity, high habitat specialization and low genetic diversity (Ellstrand & Elam 1993; Gibson et al. 2010). Developing conservation strategies for species pre- dicted to be impacted by climate change is compli- cated by uncertainty surrounding future climates and the complex and synergistic factors involved (e.g. changing community composition, species interac- tions) (Klanderud and Birks 2003; Hannah et al. 2002a; Pearson 2006). An approach that integrates data sensitive to these issues is needed (Hannah et al. 2002b), for example, by combining population genetic data with species distribution modelling and on-ground assessments (Scoble & Lowe 2010; Loss et al. 2011). Although the benefits of this approach have been raised (Alsos et al. 2009; Scoble & Lowe 2010), most studies use either population genetics or *Corresponding author. Accepted for publication February 2013. Austral Ecology (2014) 39, 17–28 © 2013 The Authors doi:10.1111/aec.12041 Austral Ecology © 2013 Ecological Society of Australia