Historically low mitochondrial DNA diversity in koalas (Phascolarctos cinereus)
Kyriakos Tsangaras1, María C Ávila-Arcos2, Yasuko Ishida3, Kristofer M Helgen4, Alfred L Roca3 and Alex D Greenwood1*
1Leibniz-Institute for Zoo and Wildlife Research, Berlin 10315, Germany.
2GeoGenetics, Natural History Museum of Denmark, University of Copenhagen, Østervoldgade 5-7, Copenhagen, DK 1350, Denmark.
3Department of Animal Sciences, University of Illinois at Urbana-Champaign, Urbana, IL 61801, USA.
4Smithsonian Institution, National Museum of Natural History, Washington, DC 20560-0108, USA.
Background The koala (Phascolarctos cinereus) is an arboreal marsupial that was historically widespread across eastern Australia until the end of the 19th century when it suffered a steep population decline. Hunting for the fur trade, habitat conversion, and disease contributed to a precipitous reduction in koala population size during the late 1800s and early 1900s. To examine the effects of these reductions in population size on koala genetic diversity, we sequenced part of the hypervariable region of mitochondrial DNA (mtDNA) in koala museum specimens collected in the 19th and 20th centuries, hypothesizing that the historical samples would exhibit greater genetic diversity.
Results The mtDNA haplotypes present in historical museum samples were identical to haplotypes found in
modern koala populations, and no novel haplotypes were detected. Rarefaction analyses suggested that the
mtDNA genetic diversity present in the museum samples was similar to that of modern koalas.
Conclusions Low mtDNA diversity may have been present in koala populations prior to recent population
declines. When considering management strategies, low genetic diversity of the mtDNA hypervariable region may
not indicate recent inbreeding or founder events but may reflect an older historical pattern for koalas.