Phylogeographic evidence links the threatened ‘Grampians’ Mountain Dragon (Rankinia diemensis Grampians) with Tasmanian populations: conservation implications in south-eastern Australia

Abstract

The importance of protecting genetic diversity within a species is increasingly being recognised by conservation management authorities. However, discrepancies in conservation policy between authorities, such as state versus national bodies, can have significant implications for species management when they cross state boundaries. We conducted a phylogeographic study of the south-eastern Australian lizard Rankinia diemensis to identify evolutionary significant units (ESUs), including the endangered population from the Grampians National Park in western Victoria. Phylogenetic analyses of two gene regions (mtDNA: ND2; nuclear: RAG1) revealed high levels of genetic divergence between populations, indicating isolation over long evolutionary time frames. Based on criteria of genetic divergence and isolation, R. diemensis contains at least two ESUs that require specific management. We found that R. diemensis from the Grampians are closely related to Tasmanian populations, but that the divergence between these regions is great enough (3.7 % mtDNA) that they should be considered separate ESUs. However, we believe the close evolutionary ties between these two regions needs to be taken into account; yet under current practises, conservation management of subspecific ESUs relies on state-level efforts. We argue that another population that occurs on the Victorian coast also qualifies as an ESU and requires targeted conservation action. Rankinia diemensis provides a case-in-point of the discrepancy between the state-level approach of maintaining genetic variation within a species and the more conservative Commonwealth focus on conserving biodiversity at the species level.