Koalas (Phascolarctos cinereus) From Queensland Are Genetically Distinct From 2 Populations in Victoria

Christina T. Ruiz-Rodriguez1, Yasuko Ishida1, Neil D. Murray2, Stephen J. O’Brien3,4, Jennifer A. M. Graves5, Alex D. Greenwood6,7, and Alfred L. Roca1,8


1 Department of Animal Sciences, University of Illinois at Urbana-Champaign, 1207 West Gregory Drive, Urbana, IL

2 Department of Ecology, Environment and Evolution, La Trobe University, Melbourne, Victoria, Australia

3 Theodosius Dobzhansky Center for Genome Bioinformatics, St. Petersburg State University, St. Petersburg, Russia

4 Oceanographic Center, Nova Southeastern University, Fort Lauderdale, FL

5 School of Life Sciences, La Trobe University, Melbourne Victoria, Australia

6 Leibniz Institute for Zoo and Wildlife Research, Berlin, Germany

7 Department of Veterinary Medicine, Freie Universität Berlin, Berlin, Germany

8 Carl R. Woese Institute for Genomic Biology, University of Illinois at Urbana-Champaign, Urbana, IL
Address correspondence to Alfred L. Roca at the address above, or e-mail:
Corresponding editor: William Murphy

The koala (Phascolarctos cinereus) suffered population declines and local extirpation due to hunting in the early 20th century, especially in southern Australia. Koalas were subsequently reintroduced to the Brisbane Ranges (BR) and Stony Rises (SR) by translocating individuals from a population on French Island descended from a small number of founders. To examine genetic diversity and north– south differentiation, we genotyped 13 microsatellite markers in 46 wild koalas from the BR and SR, and 27 Queensland koalas kept at the US zoos. The Queensland koalas displayed much higher heterozygosity (HO = 0.73) than the 2 southern Australian koala populations examined: HO = 0.49 in the BR, whereas HO = 0.41 in the SR. This is consistent with the historical accounts of bottlenecks and founder events affecting the southern populations and contrasts with reports of high genetic diversity in some southern populations. The 2 southern Australian koala populations were genetically similar (FST = 0.018, P = 0.052). By contrast, northern and southern Australian koalas were highly differentiated (FST = 0.27, P < 0.001), thereby suggesting that geographic structuring should be considered in the conservation management of koalas. Sequencing of 648bp of the mtDNA control region in Queensland koalas found 8 distinct haplotypes, one of which had not been previously detected among koalas. Queensland koalas displayed high mitochondrial haplotype diversity (H = 0.753) and nucleotide diversity (π = 0.0072), indicating along with the microsatellite data that North American zoos have maintained high levels of genetic diversity among their Queensland koalas.