Human-induced versus historical habitat shifts: Identifying the processes that shaped the genetic structure of the threatened grassland legless lizard, Delma impar

Historical and contemporary events are known to affect the genetic structure and diversity of species. Thus, in order to design effective conservation management strategies for threatened species, it is important to identify the processes that shaped their genetic patterns. The Striped Legless Lizard, Delma impar, is currently listed as a threatened species, and is restricted to the temperate grasslands of south eastern Australia. This habitat has undergone both historical climatic and recent anthropogenic distributional changes. We used mitochondrial DNA (mtDNA) and microsatellite markers to examine the phylogeography and population genetic structure of D. impar. Analysis of mtDNA revealed four distinct historically isolated lineages with high levels of genetic divergence that have been isolated for more than 1 million years. These lineages should be considered separate Evolutionarily Significant Units (ESU) for management purposes. Analysis of microsatellite genotypes did not reveal evidence of strong population sub-structuring despite recent anthropogenic fragmentation within the south west Victorian ESU. However, three populations were identified by the program Structure, which coincide with the transition of two regions with distinct soil and vegetation characteristics. Spatial autocorrelation analyses indicate that D. impar do not disperse long distances as they are genetically structured at distances less than 400 m.