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RESEARCH ARTICLE
Contents Vol 37(2)

Defining spatial genetic structure and management units for vulnerable koala (Phascolarctos cinereus) populations in the Sydney region, Australia

Tristan Lee A D , Kyall R. Zenger B , Robert L. Close C , Marilyn Jones A and David N. Phalen A
+ Author Affiliations
- Author Affiliations

A Wildlife Health and Conservation Centre, Faculty of Veterinary Science, The University of Sydney, NSW 2570, Australia.

B School of Marine & Tropical Biology, James Cook University, Townsville, Qld 4811, Australia.

C School of Biomedical and Health Sciences, University of Western Sydney, NSW 2560, Australia.

D Corresponding author. Email: t.lee@usyd.edu.au

Wildlife Research 37(2) 156-165 https://doi.org/10.1071/WR09134
Submitted: 1 October 2009  Accepted: 10 February 2010   Published: 16 April 2010

Abstract

Context. Mammal populations around the world are increasingly threatened with population fragmentation because of loss of habitat or barriers to gene flow. The investigation of koala populations in the Sydney region not only provides valuable information about this vulnerable species, but also serves as a model for other species that have suffered major rapid declines in population size, and are now recovering in fragmented habitat. The peri-urban study region allows investigation of the impact of landscape features such as major roads and housing developments on koala gene flow.

Aims. Animals originating from four geographic sampling areas around Sydney, New South Wales, Australia, were examined to determine population structure and gene flow and to identify barriers to gene flow and management units.

Methods. The present study examined 12 microsatellite loci and used Bayesian assignment methods and genic frequency analysis methods to identify demographically separate populations and barriers to gene flow between those populations.

Key results. Three discrete populations were resolved, with all displaying moderate to high levels of genetic differentiation among them (θ = 0.141–0.224). The allelic richness and heterozygosity of the Blue Mountains population (A = 6.46, HO = 0.66) is comparable to the highest diversity found in any koala population previously investigated. However, considerably lower genetic diversity was found in the Campbelltown population (A = 3.17, HO = 0.49), which also displayed evidence of a recent population bottleneck (effective population size estimated at 16–21).

Conclusions. Animals separated by a military reserve were identified as one population, suggesting that the reserve maintains gene flow within this population. By contrast, strong differentiation of two geographically close populations separated by several potential barriers to gene flow suggested these land-use features pose barriers to gene flow.

Implications. Implications of these findings for management of koala populations in the Greater Sydney region are discussed. In particular, the need to carefully consider the future of a military reserve is highlighted, along with possible solutions to allow gene flow across the proposed barrier regions. Because these are demographically separate populations, specific management plans tailored to the needs of each population will need to be formulated.

Additional keywords: gene flow, genetic diversity, koala, microsatellites, population structure.


Acknowledgements

Thanks go to all who assisted in the collection of samples, especially Melissa So, Lynn Bowden, Wendy and Michael Fairs, Steven Ward, Kieran Griffin, Mariette Ennik, Sharon Andronicos, members of the NSW Wildlife Information Rescue and Education Service (WIRES), staff at NSW National Parks and Wildlife Service, the Macarthur Advertiser, NPA Macarthur and the many members of the community who alerted us to koala sightings. We acknowledge funding from the Wildlife Health and Conservation Centre, The University of Sydney and The University of Western Sydney. We also thank the referees for their help in improving the paper.


References

Australian Bureau of Statistics (2006). ‘Population Projections Australia, Catalogue 3222.0.’ (Commonwealth Government of Australia: Canberra.)

Balkenhol, N. , and Waits, L. P. (2009). Molecular road ecology: exploring the potential of genetics for investigating transportation impacts on wildlife. Molecular Ecology 18, 4151–4164.
| Crossref | GoogleScholarGoogle Scholar | PubMed | DECC (2008). ‘Recovery Plan for the Koala.’ (Department of Environment and Climate Change NSW: Sydney.)

Di Rienzo, A. , Peterson, A. C. , Garza, J. C. , Valdes, A. M. , Slatkin, M. , and Freimer, N. B. (1994). Mutational processes of simple-sequence repeat loci in human populations. Proceedings of the National Academy of Sciences, USA 91, 3166–3170.
| Crossref | GoogleScholarGoogle Scholar | CAS | Frankham R. , Ballou J. D. , and Briscoe D. A. (2002). ‘Introduction to Conservation Genetics.’ (Cambridge University Press: Cambridge, UK.)

Goldstein, D. B. , Roemer, G. W. , Smith, D. A. , Reich, D. E. , Bergman, A. , and Wayne, R. K. (1999). The use of microsatellite variation to infer population structure and demographic history in a natural model system. Genetics 151, 797–801.
|  CAS | PubMed | Hume I. (1990). Biological basis for the vulnerability of koalas to habitat fragmentation. In ‘Koala Summit: Managing Koalas in New South Wales’. (Eds D. Lunney, C. A. Urquhart and P. Reed.) pp. 32–36. (NSW National Parks and Wildlife Service: Sydney.)

Kalinowski, S. T. (2004). Counting alleles with rarefaction: private alleles and hierarchical sampling designs. Conservation Genetics 5, 539–543.
| Crossref | GoogleScholarGoogle Scholar | CAS | Kumar S. , Tamura K. , Jakobsen I. , and Nei M. (2001). ‘MEGA2: Molecular Evolutionary Genetics Analysis Software.’ Available at http://www.megasoftware.net [verified August 2009].

Luikart, G. L. , Allendorf, F. W. , Cornuet, J. M. , and Sherwin, W. B. (1998). Distortion of allele frequency distributions provides a test for recent population bottlenecks. The Journal of Heredity 89, 238–247.
| Crossref | GoogleScholarGoogle Scholar | CAS | PubMed | Minch E. , Ruiz-Linares A. , Goldstein D. B. , Feldman M. , and Cavalli-Sforza L. (1995). ‘MICROSAT (Version 1.5b): A Computer Program for Calculating Various Statistics on Microsatellite Data.’ (Stanford University: Stanford, CA.)

Mitchell P. , and Martin R. (1990). The structure and dynamics of koala populations – French island in perspective. In ‘Biology of the Koala’. (Eds A. Lee, K. Handasyde and G. Sanson.) pp. 97–108. (Surrey Beatty: Sydney.)

Nei, M. , Maruyama, T. , and Chakraborty, R. (1975). Bottleneck effect and genetic variability in populations. Evolution 29, 1–10.
| Crossref | GoogleScholarGoogle Scholar | Peel D. , Ovenden J. R. , and Peel S. L. (2004). NeEstimator: Software for Estimating Effective Population Size, Version 1.3. Queensland Government, Department of Primary Industries and Fisheries, Brisbane.

Pérez-Espona, S. , Perez-Barberia, F. J. , McLeod, J. E. , Jiggins, C. D. , Gordon, I. J. , and Pemberton, J. M. (2008). Landscape features affect gene flow of Scottish Highland red deer (Cervus elaphus). Molecular Ecology 17, 981–996.
| Crossref | GoogleScholarGoogle Scholar | PubMed | Reed P. , and Lunney D. (1990). Habitat loss: the key problem for the long-term survival of koalas in New South Wales. In ‘Koala Summit: Managing Koalas in New South Wales’. (Eds D. Lunney, C. A. Urquhart and P. Reed.) pp. 9–31. (NSW National Parks and Wildlife Service: Sydney.)

Reed P. , Lunney D. , and Walker P. (1991). A 1986–1987 survey of the koala (Phascolarctos cinereus) in New South Wales and an ecological interpretation of its distribution. In ‘Biology of the Koala’. (Eds A. Lee, K. Handasyde and G. Sanson.) pp. 55–74. (Surrey Beatty: Sydney.)

Schwartz, M. K. , and McKelvey, K. S. (2009). Why sampling scheme matters: the effect of sampling scheme on landscape genetic results. Conservation Genetics 10, 441–452.
| Crossref | GoogleScholarGoogle Scholar | Tilley D. , and Uebel K. (1990). Observations of koala populations within the Sydney Water Board’s Upper Nepean catchment area. In ‘Koala Summit: Managing Koalas in New South Wales’. (Eds D. Lunney, C. A. Urquhart and P. Reed.) pp. 81–85. (NSW National Parks and Wildlife Service: Sydney.)

Ward S. (2002). Koalas and the community: a study of low density populations in southern Sydney. Ph.D. Thesis, University of Western Sydney.

Ward S. , and Close R. (2004). Southern Sydney’s urban koalas: community research and education at Campbelltown. In ‘Urban Wildlife: More than Meets the Eye’. pp. 44–54. (Royal Zoological Society of New South Wales: Sydney.)