Modelling the potential range of the koala at the Last Glacial Maximum: future conservation implications

Abstract

The koala Phascolarctos cinereus is the only member of the once diverse marsupial family Phascolarctidae to have survived the Last Glacial Maximum. A climate envelope model for P. cinereus was developed to predict the range for this species at present and at the Last Glacial Maximum. The model was compared to the contemporary koala records and the known fossil records of P. cinereus during the Quaternary. The predicted current core range for koalas was concentrated in southeast Queensland, eastern New South Wales and eastern Victoria. At the Last Glacial Maximum their predicted core range contracted significantly to southeast Queensland and northeast New South Wales. Our findings concord with other studies that find species experienced range contractions during glacial maxima. In the context of the future conservation planning for koalas in the wild, our historical perspective demonstrates the past adaptations of koalas to changes in climate and their probable range contraction to climatic refugia. The future survival of wide-ranging specialist species, such as the koala, may depend on identifying and protecting, future climatic refugia.Key words: Climate envelope, climatic refugia, core range, koala, Phascolarctos cinereus, Last Glacial Maximum. 984Adams-Hosking et al. Australian Zoologist volume 35 (4) 2011The role of humans as well as climate in determining the biogeography, evolution and extinction of faunas is an area of ongoing research, in particular the investigation of fauna-rich fossil caves to ascertain faunal responses to climate change during the Pleistocene (e.g. Hocknull 2007;Prideaux et al. 2007). These authors have revealed significant population fluctuations driven by glacialinterglacial cycling, but stable species composition for 500 thousand years, with the exception of the megafauna that went extinct around 70 -50 thousand years ago (Long et al. 2002). Research suggests that climate change alone was unlikely to have been the principal cause of the extinction of the megafauna and although Aboriginal hunting may have been a factor in determining the distribution and abundance of P. cinereus, there is no doubt that populations have been significantly affected by the European occupiers of Australia for the fur trade in more recent times (e.g. The modern koala's primary food source is a regionallyvariable selection of, primarily, Eucalyptus and Corymbia tree species (e.g. Moore and Foley 2000; Ellis et al. 2002). Koala populations are currently under threat from the synergistic threats of habitat loss, disease, car collisions and dog predation in coastal regions of Queensland and New South Wales (Jackson et al. 1999; Dique et al. 2003;McAlpine et al. 2006;Rhodes et al. 2008;Lunney et al. 2009). For example, the abundance of koalas on the Koala Coast of southeast Queensland is estimated to have declined by 64% in a ten year period (1999)(2000)(2001)(2002)(2003)(2004)(2005)(2006)(2007)(2008) (State of Queensland 2009). In western semi-arid and arid regions, koalas have been shown to exp...

Genome-wide SNP loci reveal novel insights into koala (Phascolarctos cinereus) population variability across its range

“…There have been several documented events of local extinctions, range contractions, expansions and translocations throughout recent history. One of the greatest historical impact on the species was hunting in the early twentieth century (Adams-Hosking et al 2011 ;Gordon et al 2006 ;Melzer et al 2000 ;Menkhorst 2008 ). Despite numbers recovering well following extensive hunting, more recent loss of habitat, increasing urbanisation and disease have led to the koala being classified as vulnerable across most of its range (NSW, ACT and QLD) by the Federal Australian government, and listed as a threatened species under the US Endangered Species Act (Fish and Wildlife Service 1998 ;Natural Resource Management Ministerial Council 2009 ).…”

Using non-invasive sampling methods to determine the prevalence and distribution of Chlamydia pecorum and koala retrovirus in a remnant koala population with conservation importance

“…Given the high prevalence and strain diversity of C. pecorum throughout the South Gippsland 20 region, and the likelihood of increasing environmental pressures in the future (e.g. climatic changes or habitat shifts; Adams-Hosking et al 2011;González-Orozco et al 2016), the incidence and/or severity of overt disease may increase in the region over the coming years. The indication that KoRV-A infection 25 may be having a negative impact on koalas is also of concern.…”

Landscape, koalas and people: A historical account of koala populations and their environment in South Gippsland

“…In addition to the widespread clearing of habitat for agriculture, hunting in order to harvest pelts for the fur trade had a major impact on koala populations (Lewis 1934). In the future, rapid changes in climate are anticipated to result in contractions and spatial shifts in the distribution of most eucalypt species, which is of significant conservation concern for koalas (Adams-Hosking et al 2011;McAlpine et al 2015;González-Orozco et al 2016). Continued habitat loss and forest fragmentation, due to urbanisation, industrial developments, forestry and fires have ongoing effects on contemporary koala populations, while the frequency and severity of droughts and fires, predicted to increase in Australia due to climate change (Hennessy et al 2005;Bradstock 2010), will also continue to put pressure on this species.…”

“…This fact suggests that the southerly expansion of koalas into Victoria occurred relatively recently (Sherwin et al 2000), after the inundation (around 10,000 years ago) of the Bassian Plain, which formed the land bridge between present day Victoria and Tasmania. It is also possible that more southerly cooler climates at the time rendered Tasmania unsuitable for koalas, though currently, parts of Tasmania are modelled as climatically suitable for koalas (Adams-Hosking et al 2011).…”