RESEARCH ARTICLE Genetic analysis reveals the costs of peri-urban development for the endangered grassland earless dragon Marion Hoehn • Wendy Dimond • Will Osborne • Stephen D. Sarre Received: 14 April 2013 / Accepted: 10 July 2013 / Published online: 7 August 2013 Ó Springer Science+Business Media Dordrecht 2013 Abstract Australia’s natural temperate grasslands have diminished to 0.5 % of their former area since European settlement and, as a consequence, are highly fragmented and modified. Many vertebrate species that live in temperate grasslands are habitat specialists and therefore are at risk of decline through habitat loss and fragmentation. The grass- land earless dragon (Tympanocryptis pinguicolla) is one such species. Once widespread, T. pinguicolla is now restricted to two general locations; the first is near Canberra in the Australian Capital Territory (including some adjacent land near Queanbeyan), and the second is the Monaro Tablelands in New South Wales. Here, we use microsatellite DNA data collected from the largest remaining populations near Canberra to examine genetic structure in this species in the context of the rapidly expanding urban landscape in this region. Our study revealed that, despite separation by only relatively small distances (largest distance *13 km), the T. pinguicolla populations are highly genetically structured with little admixture. Our analyses also revealed that the population with the largest census size, but which has recently crashed in population size, exhibited little detect- able gene flow to other populations and is essentially iso- lated. Our data indicate that significant barriers to dispersal exist among the remaining T. pinguicolla populations and that management of this species cannot rely on natural dis- persal to bolster declining populations. Many different agencies and landholders are responsible for the protection of these remnant populations and a co-ordinated effort is required to provide reasonable confidence that the species will persist. Keywords Habitat fragmentation Á Native temperate grasslands Á Grassland earless dragon Á Microsatellites Á Spatial autocorrelation Á Recent effective population size Introduction Understanding the factors that modify dispersal has long been a central theme in conservation biology (Clobert et al. 2001; Hoehn et al. 2007, 2012; Row et al. 2010). This is because dispersal is essential for the rescue of populations in decline through immigration and by enabling gene flow to occur and thereby protecting small populations from genetic drift and inbreeding. Habitat fragmentation, a process in which a continuous landscape is divided into a number of smaller, isolated patches (Keyghobadi 2007) disrupts this gene flow. In order to produce realistic management strategies for spe- cies subject to habitat fragmentation, habitat quality within remnants and connectedness among them must be understood (Armstrong et al. 2005). Disentangling the relative role of contemporary and historical processes is important, espe- cially when a lack of continuous habitat makes comparative studies of fragmented and unfragmented populations impossible (Bush et al. 2010; Chiucchi and Gibbs 2010). An effective approach to this problem is to examine population genetic structure using molecular approaches (Beerli and Felsenstein 2001; Pritchard et al. 2007). Natural grasslands are among the world’s most frag- mented and threatened ecosystems having been subjected to wide-scale destruction through agriculture and other M. Hoehn Á W. Dimond Á W. Osborne Á S. D. Sarre Institute for Applied Ecology, University of Canberra, Canberra, ACT 2601, Australia Present Address: M. Hoehn (&) CSIRO Ecosystem Sciences, GPO Box 1700, Canberra, ACT 2601, Australia e-mail: marion.hoehn.1206@gmail.com 123 Conserv Genet (2013) 14:1269–1278 DOI 10.1007/s10592-013-0515-6