Getting a Little Too Close and Cuddly

Since European settlement, the population of koalas in southern Australia has been affected by many relocations and population crashes which, has created a history where several populations have been founded by very few animals. This has not caused the koala in these areas to become endangered, but has resulted in a significant reduction in their genetic variability. In Queensland, where the koala populations have not been as greatly affected by humans, there is a much higher variability in their genetics.

Decline of genetic variability can lead to temporary reduction in fitness in the areas such as survival, reproduction, growth rates and the ability to adapt to long-term environmental changes. Inbreeding in koalas from isolated, fragmented populations has shown to cause physical abnormalities. Also, a correlation has been found between increased inbreeding and a rising number of juvenile mortalities.

Studies have been undertaken observing the mitochondrial DNA in koala populations. In a study, 18 different haplotypes were found within selection of certain koala populations but with only one or two haplotypes per population. The nucleotide diversity of koalas was shown to be up to eight times lower when compared to other marsupials.

A significant part conservation plans for the koala should be focused on their genetic management. The koalas today are the sole member of their family and if their genetic variability is allowed to reduce further, this may result in much more adverse consequences in the future.

Written by: Jade Weatherley

Primary Resources
1. Sherwin, W.B., Timms, P., Wilcken, J., Houlden, B., 2000. Analysis and Conservation Implications of Koala Genetics.
http://www.jstor.org/sici?sici=0888-8892(200006)14%3A3%3C639%3AAACIOK%3E2.0.CO%3B2-1

2. Houlden, B.A., Costello, B.H., Sharkey, D., Fowler, E.V., Melzer, A., Ellis, W., Carrick, F., Baverstock, P.R., Elphinstone, M.S., 1999. Phylogeographic differentiation in the mitochondrial control region in the koala, Phascolarctos cinereus (Goldfuss 1817). Molecular Ecology 8. 999-1011.
http://www.blackwell-synergy.com/doi/pdf/10.1046/j.1365-294x.1999.00656.x

Secondary Resources
3. Taylor, A.C., Graves, J.M., Murray, N.D., O’Brien, S.J., Sherwin, B., 1996. Conservation genetics of the koala (Phascolarctos cinereus): low mitochondrial DNA variation amongst southern Australian populations. Genetical Research 69. 25-30.
http://www.ncbi.nlm.nih.gov/pubmed/9164173

4. http://en.wikipedia.org/wiki/Mitochondrial_DNA

5. http://en.wikipedia.org/wiki/Haplotype

6. https://www.savethekoala.com/islandkoalas.html

7. http://www.answers.com/topic/koala