Significant population genetic structuring but a lack of phylogeographic structuring in the endemic Tasmanian tree frog (Litoria burrowsae)

Abstract

Conservation of frogs is of global concern, owing to declines resulting from habitat destruction, global climate change, and disease. Knowledge of genetic variation in frog species is therefore desirable for the identification of management units. Here we surveyed mitochondrial DNA sequence variation in the Tasmanian endemic hylid frog Litoria burrowsae, which is infected by chytrid fungus, Batrachochytrium dendrobatidis, and may be declining. Neither phylogeographic structure nor deep phylogenetic divergence was detected in the species, although its populations were highly differentiated with respect to haplotype frequencies. The low-haplotype diversity in L. burrowsae suggests a recent bottleneck in the species, and population genetic structuring may reflect isolation by distance as well as founder effects associated with range expansion. Three putative management units were identified that require verification based on nuclear DNA variation and adaptation to local environments.

Persistence and dispersal in a Southern Hemisphere glaciated landscape: the phylogeography of the spotted snow skink (Niveoscincus ocellatus) in Tasmania

“…However, these patterns contrast strongly with those typically observed in other parts of Australia and the Southern Hemisphere, which have suggested greater numbers of refugia, including many micro-refugia (small pockets of suitable habitat in an otherwise uninhabitable landscape) [ 34 ], and genetic structuring reflecting events which pre-date the LGM [ 17 , 18 , 22 , 24 , 35 ]. Consequently, Tasmania represents an important region for further research to better develop our understanding of the effects of Pleistocene glaciations on species distributions [ 36 ]. In this context, lizards have recently been highlighted as good models for use in phylogeographic studies [ 37 ].…”

Phylogeographic parallelism: Concordant patterns in closely related species illuminate underlying mechanisms in the historically glaciated Tasmanian landscape

“…During glacial periods, the low-lying central north of Tasmania and the low relief Bassian Plain to the north were probably arid, windswept treeless steppe (Kirkpatrick & Fowler, 1998), inhibiting movement in a range of taxa, although pollen records are lacking for this region (Colhoun & Shimeld, 2012). Distinct northwest Tasmanian lineages are also observed for C. ocellatus (Cliff et al, 2015) and a range of other taxa (e.g., Chapple et al, 2005;Macqueen et al, 2009;Bloomfield et al, 2011;Brüniche-Olsen et al, 2014;Zhang et al, 2014). Genetic isolation between the remaining Carinascincus major clades may also reflect utilisation of disjunct regional refugia during Pleistocene glaciations.…”