Genetic structure and diversity of the koala population in South Gippsland, Victoria : A remnant population of high conservation significance
- Authors: Wedrowicz, Faye , Mosse, Jennifer , Wright, Wendy , Hogan, Fiona
- Date: 2018
- Type: Text , Journal article
- Relation: Conservation Genetics Vol. 19, no. 3 (2018), p. 713-728
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- Description: In the Australian state of Victoria, the history of koalas and their management has resulted in the homogenisation and reduction of genetic diversity in many contemporary populations. Decreased genetic diversity may reduce a species’ ability to adapt to future environmental pressures such as climate change or disease. The South Gippsland koala population is considered to be unique in Victoria, as it is believed to be a remnant population, not originating from managed populations that have low genetic variation. This study investigated genetic structure and diversity of koalas in South Gippsland, with comparison to other populations in Victoria (French Island/Cape Otway, FI and Raymond Island, RI), New South Wales and south east Queensland. Population analyses were undertaken using both microsatellite genotype and mitochondrial DNA sequence data. Non-invasive sampling of koala scats was used to source koala DNA, allowing 222 South Gippsland koalas to be genotyped. Using nuclear data the South Gippsland koala population was found to be significantly differentiated (Djost 95% CI SG–RI = 0.03–0.06 and SG–FI = 0.08–012) and more diverse (AR 95% CI SG = 4.7–5.6, RI = 3.1–3.3, FI = 3.0–3.3; p = 0.001) than other Victorian koala populations, supporting the premise that koalas in the South Gippsland region are part of a remnant population, not derived from translocated island stock. These results were also supported by mitochondrial data where eight haplotypes (Pc4, Pc17, Pc26, Pc27, and Pc56–Pc59) were identified in South Gippsland while a single haplotype (Pc27) was found in all island koalas tested. Compared to other Victorian koala populations, greater genetic diversity found in South Gippsland koalas, may provide this population with a greater chance of survival in the face of future environmental pressures. The South Gippsland koala population is, therefore, of high conservation significance, warranting the implementation of strategies to conserve this population and its diversity into the future.
Isolating DNA sourced non-invasively from koala scats: a comparison of four commercial DNA stool kits
- Authors: Wedrowicz, Faye , Mosse, Jennifer , Wright, Wendy , Hogan, Fiona
- Date: 2018
- Type: Text , Journal article
- Relation: Conservation Genetics Resources Vol. , no. (2018), p.
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- Description: Genetic sampling from faeces is a useful method for obtaining DNA samples non-invasively. The quantity and quality of DNA isolated from faecal samples is, however, an important factor affecting the success of downstream analyses. Commercial DNA isolation kits offer an efficient and convenient means for recovering DNA, but the kit methodology can influence the quantity and quality of DNA obtained. Comparisons of kit performance for the isolation of DNA from non-invasive sources for ecological studies based on genetic analysis are uncommon in the literature. This study compared the quantity and quality of DNA isolated from surface washings of fresh koala (Phascolarctos cinereus) faecal pellets (scats) using four commercial DNA isolation kits: Axygen® AxyPrep™ MAG Soil, Stool, and Water DNA Kit (AX), Bioline ISOLATE Fecal DNA Kit (BL), Qiagen QIAamp® Fast DNA Stool Mini Kit (QFS), and Qiagen QIAamp® DNA Stool Mini Kit (QS). DNA quantitation, standard PCR and electrophoresis, real time PCR and replicate genotyping using capillary electrophoresis were used to compare the performance of resultant DNA isolates. The performance of DNA isolated from koala scats varied substantially with the DNA kit utilised. All kits provided accurate genotypes but with differing amounts of missing data. Overall, kit AX performed best, providing DNA isolates of higher quantity and quality compared to kit QS, which has previously been thoroughly assessed for genotyping reliability using DNA from koala scats. Given the high variability noted, assessing kit performance is an important way to maximise data quality from non-invasively sourced DNA.
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
- Authors: Wedrowicz, Faye , Mosse, Jennifer , Wright, Wendy , Hogan, Fiona
- Date: 2018
- Type: Text , Journal article
- Relation: Wildlife Research Vol. 45, no. 4 (2018), p. 366-380
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- Description: Context Pathogenic infections are an important consideration for the conservation of native species, but obtaining such data from wild populations can be expensive and difficult. Two pathogens have been implicated in the decline of some koala (Phascolarctos cinereus) populations: Urogenital infection with Chlamydia pecorum and koala retrovirus subgroup A (KoRV-A). Pathogen data for a wild koala population of conservation importance in South Gippsland, Victoria are essentially absent. Aims This study uses non-invasive sampling of koala scats to provide prevalence and genotype data for C. pecorum and KoRV-A in the South Gippsland koala population, and compares pathogen prevalence between wild koalas and koalas in rescue shelters. Methods C. pecorum and KoRV-A provirus were detected by PCR of DNA isolated from scats collected in the field. Pathogen genetic variation was investigated using DNA sequencing of the C. pecorum ompA and KoRV-A env genes. Key results C. pecorum and KoRV-A were detected in 61% and 27% of wild South Gippsland individuals tested, respectively. KoRV-A infection tended to be higher in shelter koalas compared with wild koalas. In contrast with other Victorian koala populations sampled, greater pathogen diversity was present in South Gippsland. Conclusions In the South Gippsland koala population, C. pecorum is widespread and common whereas KoRV appears less prevalent than previously thought. Further work exploring the dynamics of these pathogens in South Gippsland koalas is warranted and may help inform future conservation strategies for this important population. Implications Non-invasive genetic sampling from scats is a powerful method for obtaining data regarding pathogen prevalence and diversity in wildlife. The use of non-invasive methods for the study of pathogens may help fill research gaps in a way that would be difficult or expensive to achieve using traditional methods.
Landscape, koalas and people : A historical account of koala populations and their environment in South Gippsland
- Authors: Wedrowicz, Faye , Wright, Wendy , Schlagloth, Rolf , Santamaria, Flavia , Cahir, David (Fred)
- Date: 2017
- Type: Text , Journal article
- Relation: Australian Zoologist Vol. 38, no. 4 (2017), p. 518-536
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- Description: We present an ecological history of the koala (Phascolarctos cinereus) population and its environment in South Gippsland, Victoria, both pre- and post-European settlement. We consider the role that the region's history may have had on the genetic structure of the current koala population in South Gippsland, which is the only known koala population in Victoria that does not originate from animals re-introduced as part of the Victorian translocation program. Following European colonisation of Australia, a range of anthropogenic factors, including hunting for the fur trade, resulted in widespread population declines for the koala. In Victoria, the situation was extreme. Currently, many koala populations in Victoria are derived from only a few individuals which existed less than 120 years ago. These populations therefore have comparatively low genetic diversity, a factor that plays a key role in long term population viability. In Victoria, the koala is not listed as a threatened species. Despite the low genetic diversity of most populations, the species is widely distributed across the state, and relatively common. Indeed, some populations are considered overabundant. However, many koala populations are not abundant, and population data are lacking for most. The South Gippsland koala population is of high conservation significance as it has greater genetic diversity compared to other Victorian populations, though there is little additional data to inform its conservation. An improved understanding of genetic diversity and gene flow between populations across the koala's range is required to guide the conservation of genetic diversity in this species. Monitoring population size, health and genetic relationships both within and between koala populations will enable better conservation outcomes.