Genetic monitoring reveals significant population structure in eastern quolls: implications for the conservation of a threatened carnivorous marsupial Maria J. Cardoso A , Nick Mooney B , Mark D. B. Eldridge C,D , Karen B. Firestone A and William B. Sherwin A A Evolution and Ecology Research Centre, School of Biological, Earth and Environmental Sciences, University of New South Wales, Kensington, NSW 2052, Australia. B Department of Primary Industries, Parks, Water and Environment, Wildlife Management and Fox Eradication Branch, GPO Box 44, Hobart, Tas. 7001, Australia. C Australian Museum Research Institute, Australian Museum, 6 College Street, Sydney, NSW 2010, Australia. D Corresponding author. Email: mark.eldridge@austmus.gov.au Abstract. The eastern quoll (Dasyurus viverrinus), while still relatively abundant in Tasmania, is now threatened by the recently introduced European red fox (Vulpes vulpes). Due to a lack of demographic information on eastern quolls, molecular data become a crucial surrogate to inform the management of the species. The aim of this study was to acquire baseline genetic data for use in current and future conservation strategies. Genetic variation, at seven microsatellite loci, was lower in Tasmanian eastern quolls than in quoll species from the Australian mainland. Within Tasmania, genetic variation was greater in central than peripheral populations, with the lowest levels detected on Bruny Island. Significant genetic population structure, consistent with regional differentiation, appears related to geographic distance among populations. Levels of gene flow appeared moderate, with genetic admixture greatest among central populations. Therefore, eastern quolls from genetically diverse central Tasmanian populations will become an important source for conservation initiatives if widespread declines begin to occur. Ongoing genetic monitoring of existing populations will allow conservation strategies to be adaptive. However, in order for translocations to be successful, managers must not only consider the genetic composition of founding individuals, but also habitat-specific adaptations, disease and threatening processes at translocation sites. Additional keywords: Dasyurus, management, microsatellites, population genetics, Tasmania. Received 25 October 2013, accepted 6 March 2014, published online 28 May 2014 Introduction Anthropogenic disturbance threatens the survival of species worldwide (Cardillo et al. 2004), with Australian mammals having fared particularly poorly since European settlement (Short and Smith 1994). Since the disappearance of populations is a prelude to species extinction (Ceballos and Ehrlich 2002), monitoring wild populations is crucial to establishing the conservation status of species thought to be at risk (Maudet et al. 2002). Although population persistence may be influenced by demographic and environmental stochastic factors, the evidence for genetic effects on fitness and persistence in wild populations is now also strong (Bouzat et al. 1998; Reed and Frankham 2003). Baseline genetic data gathered before populations decline have the potential to shape and inform proactive management and so reduce extinction risk (Drechsler et al. 2011). Acquiring demographic data on population size, dispersal and population structure using mark–recapture methods can often be ineffective, expensive and time consuming. However, similar information can often be more readily obtained from population genetic data, which can then be used to guide management strategies (Eldridge et al. 2004). Although the effective population size (Ne) is an important parameter in conservation biology, accurately estimating the effective size of natural populations is difficult (Kalinowski and Waples 2002). When temporal samples are not available, a single sample can be used; although one-sample Ne estimators have often been biased and imprecise, recent improvements have made these estimators more useful (Beebee 2009; Luikart et al. 2010). However, in order to maximise confidence in the results, it remains important to compare different Ne estimators, as well as the methods used to analyse patterns of genetic population structure. Many species occur as metapopulations where discrete local populations are connected by dispersal (Hanski and Gaggiotti 2004). Genetic discontinuities within and between populations in relation to natural and/or anthropogenic environmental features become important when planning management strategies such as Journal compilation Ó Australian Mammal Society 2014 www.publish.csiro.au/journals/am CSIRO PUBLISHING Australian Mammalogy, 2014, 36, 169–177 http://dx.doi.org/10.1071/AM13035