Hybridisation rates, population structure, and dispersal of sambar deer (Cervus unicolor) and rusa deer (Cervus timorensis) in south-eastern Australia
- Hill, Erin, Murphy, Nicholas, Li-Williams, Scarlett, Davies, Christopher, Forsyth, David, Comte, Sebastien, Rollins, Lee, Hogan, Fiona, Wedrowicz, Faye, Crittle, Troy, Thomas, Elaine, Woodford, Luke, Pacioni, Carlo
- Authors: Hill, Erin , Murphy, Nicholas , Li-Williams, Scarlett , Davies, Christopher , Forsyth, David , Comte, Sebastien , Rollins, Lee , Hogan, Fiona , Wedrowicz, Faye , Crittle, Troy , Thomas, Elaine , Woodford, Luke , Pacioni, Carlo
- Date: 2023
- Type: Text , Journal article
- Relation: Wildlife Research Vol. 50, no. 9 (2023), p. 669-687
- Full Text:
- Reviewed:
- Description: Context. Introduced populations of sambar deer (Cervus unicolor) and rusa deer (Cervus timorensis) are present across south-eastern Australia and are subject to local population control to alleviate their negative impacts. For management to be effective, identification of dispersal capability and management units is necessary. These species also readily hybridise, so additional investigation of hybridisation rates across their distributions is necessary to understand the interactions between the two species. Aims. Measure the hybridisation rate of sambar and rusa deer, assess broad-scale population structure present within both species and identify distinct management units for future population control, and measure the likely dispersal capability of both species. Methods. In total, 198 sambar deer, 189 rusa deer, and three suspected hybrid samples were collected across Victoria and New South Wales (NSW). After sequencing and filtering, 14 099 polymorphic single-nucleotide polymorphism (SNP) markers were retained for analysis. Hybridisation rates were assessed before the data were split by species to identify population structure, diversity indices, and dispersal distances. Key results. Across the entire dataset, 17 hybrids were detected. Broad-scale population structure was evident in sambar deer, but not among the sites where rusa deer were sampled. Analysis of dispersal ability showed that a majority of deer movement occurred within 20 km in both species, suggesting limited dispersal. Conclusions. Distinct management units of sambar deer can be identified from the dataset, allowing independent population control. Although broad-scale population structure was not evident in the rusa deer populations, dispersal limits identified suggest that rusa deer sites sampled in this study could be managed separately. Sambar × rusa deer hybrids are present in both Victoria and NSW and can be difficult to detect on the basis of morphology alone. Implications. Genetic analysis can identify broad-scale management units necessary for population control, and estimates of dispersal capability can assist in delineating management units where broad-scale population structure may not be apparent. The negative impacts associated with hybridisation require further investigation to determine whether removal of hybrids should be considered a priority management aim. © 2023 The Author(s) (or their employer(s)). Published by CSIRO Publishing.
- Authors: Hill, Erin , Murphy, Nicholas , Li-Williams, Scarlett , Davies, Christopher , Forsyth, David , Comte, Sebastien , Rollins, Lee , Hogan, Fiona , Wedrowicz, Faye , Crittle, Troy , Thomas, Elaine , Woodford, Luke , Pacioni, Carlo
- Date: 2023
- Type: Text , Journal article
- Relation: Wildlife Research Vol. 50, no. 9 (2023), p. 669-687
- Full Text:
- Reviewed:
- Description: Context. Introduced populations of sambar deer (Cervus unicolor) and rusa deer (Cervus timorensis) are present across south-eastern Australia and are subject to local population control to alleviate their negative impacts. For management to be effective, identification of dispersal capability and management units is necessary. These species also readily hybridise, so additional investigation of hybridisation rates across their distributions is necessary to understand the interactions between the two species. Aims. Measure the hybridisation rate of sambar and rusa deer, assess broad-scale population structure present within both species and identify distinct management units for future population control, and measure the likely dispersal capability of both species. Methods. In total, 198 sambar deer, 189 rusa deer, and three suspected hybrid samples were collected across Victoria and New South Wales (NSW). After sequencing and filtering, 14 099 polymorphic single-nucleotide polymorphism (SNP) markers were retained for analysis. Hybridisation rates were assessed before the data were split by species to identify population structure, diversity indices, and dispersal distances. Key results. Across the entire dataset, 17 hybrids were detected. Broad-scale population structure was evident in sambar deer, but not among the sites where rusa deer were sampled. Analysis of dispersal ability showed that a majority of deer movement occurred within 20 km in both species, suggesting limited dispersal. Conclusions. Distinct management units of sambar deer can be identified from the dataset, allowing independent population control. Although broad-scale population structure was not evident in the rusa deer populations, dispersal limits identified suggest that rusa deer sites sampled in this study could be managed separately. Sambar × rusa deer hybrids are present in both Victoria and NSW and can be difficult to detect on the basis of morphology alone. Implications. Genetic analysis can identify broad-scale management units necessary for population control, and estimates of dispersal capability can assist in delineating management units where broad-scale population structure may not be apparent. The negative impacts associated with hybridisation require further investigation to determine whether removal of hybrids should be considered a priority management aim. © 2023 The Author(s) (or their employer(s)). Published by CSIRO Publishing.
Delineating genetic management units of sambar deer (Rusa unicolor) in south-eastern Australia, using opportunistic tissue sampling and targeted scat collection
- Davies, Christopher, Wright, Wendy, Wedrowicz, Faye, Pacioni, Carlo, Hogan, Fiona
- Authors: Davies, Christopher , Wright, Wendy , Wedrowicz, Faye , Pacioni, Carlo , Hogan, Fiona
- Date: 2022
- Type: Text , Journal article
- Relation: Wildlife Research Vol. 49, no. 2 (2022), p. 147-157
- Full Text:
- Reviewed:
- Description: Context: Invasive species are major drivers of biodiversity loss, requiring management to reduce their ecological impacts. Population genetics can be applied to delineate management units, providing information that can help plan and improve control strategies. Aim: The present study aims to use a genetic approach to test the existence of three previously proposed sambar deer populations in south-eastern Australia. In doing so, the study aims to delineate management units of sambar deer in south-eastern Australia. Methods: Sambar deer DNA was sourced opportunistically from tissue samples and targeted scat collection. Samples were collected from three areas in Victoria, south-eastern Australia: Mt Cole (MC), French Island (FI) and eastern Victoria (EV). Contemporary population structure was assessed using a suite of 11 polymorphic microsatellite markers. The number of maternal sambar deer lineages in south-eastern Australia was investigated through sequencing of the mitochondrial (mt)DNA control region. Key results: Three distinct genetic clusters were identified. Differentiation among inferred clusters was found to be high, with FST ranging from 0.24 between EV and FI clusters and 0.48 between MC and FI clusters. Two mtDNA haplotypes were identified; R.u1 was found throughout EV and FI, and R.u2 was unique to MC. DNA isolated from scats provided reliable data and proved critical for sampling areas where hunting and culling of deer are not generally undertaken. Conclusions: Three genetically distinct sambar deer management units in south-eastern Australia are defined-MC, FI and EV. Sambar deer control strategies should be applied to each management unit independently. This may be difficult or infeasible for the EV management unit, which is large and geographically complex. Further research may help identify additional fine-scale genetic structure in EV, allowing smaller, more practicable management units to be identified. Implications: Genetic data can be used to identify management units for invasive species, which will be critical for the development of future management strategies and improving control operations. The approach outlined here could also be applied to improve the management of other introduced deer species in south-eastern Australia. © 2022 CSIRO Open Access.
- Authors: Davies, Christopher , Wright, Wendy , Wedrowicz, Faye , Pacioni, Carlo , Hogan, Fiona
- Date: 2022
- Type: Text , Journal article
- Relation: Wildlife Research Vol. 49, no. 2 (2022), p. 147-157
- Full Text:
- Reviewed:
- Description: Context: Invasive species are major drivers of biodiversity loss, requiring management to reduce their ecological impacts. Population genetics can be applied to delineate management units, providing information that can help plan and improve control strategies. Aim: The present study aims to use a genetic approach to test the existence of three previously proposed sambar deer populations in south-eastern Australia. In doing so, the study aims to delineate management units of sambar deer in south-eastern Australia. Methods: Sambar deer DNA was sourced opportunistically from tissue samples and targeted scat collection. Samples were collected from three areas in Victoria, south-eastern Australia: Mt Cole (MC), French Island (FI) and eastern Victoria (EV). Contemporary population structure was assessed using a suite of 11 polymorphic microsatellite markers. The number of maternal sambar deer lineages in south-eastern Australia was investigated through sequencing of the mitochondrial (mt)DNA control region. Key results: Three distinct genetic clusters were identified. Differentiation among inferred clusters was found to be high, with FST ranging from 0.24 between EV and FI clusters and 0.48 between MC and FI clusters. Two mtDNA haplotypes were identified; R.u1 was found throughout EV and FI, and R.u2 was unique to MC. DNA isolated from scats provided reliable data and proved critical for sampling areas where hunting and culling of deer are not generally undertaken. Conclusions: Three genetically distinct sambar deer management units in south-eastern Australia are defined-MC, FI and EV. Sambar deer control strategies should be applied to each management unit independently. This may be difficult or infeasible for the EV management unit, which is large and geographically complex. Further research may help identify additional fine-scale genetic structure in EV, allowing smaller, more practicable management units to be identified. Implications: Genetic data can be used to identify management units for invasive species, which will be critical for the development of future management strategies and improving control operations. The approach outlined here could also be applied to improve the management of other introduced deer species in south-eastern Australia. © 2022 CSIRO Open Access.
- Davies, Christopher, Wright, Wendy, Hogan, Fiona, Davies, Hugh
- Authors: Davies, Christopher , Wright, Wendy , Hogan, Fiona , Davies, Hugh
- Date: 2020
- Type: Text , Journal article
- Relation: Australian Mammalogy Vol. 42, no. 3 (2020), p. 312-320
- Full Text: false
- Reviewed:
- Description: Introduced sambar deer (Rusa unicolor) are increasing in abundance and distribution across much of south-eastern Australia and causing damage to native ecosystems. However, the current paucity of knowledge surrounding many aspects of sambar deer ecology is limiting our capacity to make informed management decisions, and properly gauge the extent of deer impacts. Here we investigate correlates of sambar deer detectability and describe activity patterns of sambar deer in Baw Baw National Park (BBNP) to inform control operations. Camera traps were deployed in BBNP between October and December 2016. We used an occupancy modelling framework to investigate sambar deer detectability and camera trap record time stamps to determine sambar deer activity patterns. Sambar deer were found to be significantly more detectable near roads and in areas of sparse tree density and displayed strong crepuscular activity patterns. Control operations carried out along roads at dawn and dusk could be effective, at least in the short term. Likewise, aerial culling could be an effective control option for sambar deer populations in BBNP. This study highlights the utility of camera trap data to inform the application of control operations for cryptic invasive species. © 2020 Australian Mammal Society.
Predicting deer-vehicle collision risk across Victoria, Australia
- Davies, Christopher, Wright, Wendy, Hogan, Fiona, Visintin, Casey
- Authors: Davies, Christopher , Wright, Wendy , Hogan, Fiona , Visintin, Casey
- Date: 2020
- Type: Text , Journal article
- Relation: Australian Mammalogy Vol. 42, no. 3 (2020), p. 293-301
- Full Text: false
- Reviewed:
- Description: The risk of deer-vehicle collisions (DVCs) is increasing in south-east Australia as populations of introduced deer expand rapidly. There are no investigations of the spatial and temporal patterns of DVC or predictions of where such collisions are most likely to occur. Here, we use an analytical framework to model deer distribution and vehicle movements in order to predict DVC risk across the State of Victoria. We modelled the occurrence of deer using existing occurrence records and geographic climatic variables. We estimated patterns of vehicular movements from records of average annual daily traffic and speeds. Given the low number of DVCs reported in Victoria, we used a generalised linear regression model fitted to DVCs in California, USA. The fitted model coefficients suggested high collision risk on road segments with high predicted deer occurrence, moderate traffic volume and high traffic speed. We used the California deer model to predict collision risk on Victorian roads and validated the predictions with two independent datasets of DVC records from Victoria. The California deer model performed well when comparing predictions of collision risk to the independent DVC datasets and generated plausible DVC risk predictions across the State of Victoria. © 2020 Australian Mammal Society.
- Description: This research was supported by an Australian Government Research Training Program (RTP) scholarship and Federation University Australia’s School of Health and Life Science.
New insights into wild deer population genetics, ecology and impacts : implications for management in south eastern Australia
- Authors: Davies, Christopher
- Date: 2019
- Type: Text , Thesis , PhD
- Full Text:
- Description: This thesis is a compilation of my own work, driven by my interest into the ecology and impacts of introduced deer in Victoria. My interest in deer initially lead me to undertake an honours project, focussed on deer as a vector for parasites that can affect domestic livestock. During my honours year it became apparent that little was known about the ecology of wild deer throughout south east Australia. My PhD study was therefore developed to fill knowledge gaps of deer ecology, with a focus on developing and optimising ecological tools to generate data to improve deer management strategies. There are many methods available which can be used to collect ecological data on invasive species, such as deer. For my study, I chose methods from four quite discrete fields; global positioning systems (GPS) tracking, population genetics, camera trapping and spatial modelling. These methods were chosen as they are commonly used in ecological studies of invasive species. During my candidature significant attempts were made to deploy GPS collars onto sambar deer to investigate their movement patterns. Movement pattern data is extremely useful and can provide insights into habitat preferences, dispersal ability and other information useful for management. Significant time (around 12 months) was spent applying for ethics approval, gaining relevant approvals, permits and licenses to perform this work as well as performing collaring attempts. Unfortunately all attempts were unsuccessful and the investigation of sambar deer movement patterns had to be abandoned. This highlights the difficulties of working with cryptic deer species inhabiting difficult terrain. The other fields of research pursued (population genetics, camera trapping and spatial modelling) were more successful, the results of which are presented and discussed in this thesis. As the three methods employed in this study are taken from very different fields, a number of experts were enlisted to guide the respective data chapters. The population genetic studies (Chapters two and three) were guided by my primary supervisor Dr Fiona Hogan. I conducted all scat collections from across Victoria, including French Island and Mount Cole and performed all DNA isolations (over 300 in total). Population structure analysis for chapter three was undertaken with the assistance of Dr Faye Wedrowicz and Dr Carlo Pacioni. The camera trapping study (Chapter four) involved deploying camera traps in Baw Baw National Park, which I conducted myself. Occupancy and detectability data analysis for chapter four was performed with the assistance of Dr Hugh Davies. Spatial modelling (Chapter five) which focussed on modelling deer-vehicle collision risk across Victoria was directed by Dr Casey Visintin. Chapter’s two to five are written as independent scientific publications, therefore there is some unavoidable repetition within the thesis as a whole. Minor changes have been made to the formatting of the published papers to keep style consistent within the thesis.
- Description: Doctor of Philosophy
- Authors: Davies, Christopher
- Date: 2019
- Type: Text , Thesis , PhD
- Full Text:
- Description: This thesis is a compilation of my own work, driven by my interest into the ecology and impacts of introduced deer in Victoria. My interest in deer initially lead me to undertake an honours project, focussed on deer as a vector for parasites that can affect domestic livestock. During my honours year it became apparent that little was known about the ecology of wild deer throughout south east Australia. My PhD study was therefore developed to fill knowledge gaps of deer ecology, with a focus on developing and optimising ecological tools to generate data to improve deer management strategies. There are many methods available which can be used to collect ecological data on invasive species, such as deer. For my study, I chose methods from four quite discrete fields; global positioning systems (GPS) tracking, population genetics, camera trapping and spatial modelling. These methods were chosen as they are commonly used in ecological studies of invasive species. During my candidature significant attempts were made to deploy GPS collars onto sambar deer to investigate their movement patterns. Movement pattern data is extremely useful and can provide insights into habitat preferences, dispersal ability and other information useful for management. Significant time (around 12 months) was spent applying for ethics approval, gaining relevant approvals, permits and licenses to perform this work as well as performing collaring attempts. Unfortunately all attempts were unsuccessful and the investigation of sambar deer movement patterns had to be abandoned. This highlights the difficulties of working with cryptic deer species inhabiting difficult terrain. The other fields of research pursued (population genetics, camera trapping and spatial modelling) were more successful, the results of which are presented and discussed in this thesis. As the three methods employed in this study are taken from very different fields, a number of experts were enlisted to guide the respective data chapters. The population genetic studies (Chapters two and three) were guided by my primary supervisor Dr Fiona Hogan. I conducted all scat collections from across Victoria, including French Island and Mount Cole and performed all DNA isolations (over 300 in total). Population structure analysis for chapter three was undertaken with the assistance of Dr Faye Wedrowicz and Dr Carlo Pacioni. The camera trapping study (Chapter four) involved deploying camera traps in Baw Baw National Park, which I conducted myself. Occupancy and detectability data analysis for chapter four was performed with the assistance of Dr Hugh Davies. Spatial modelling (Chapter five) which focussed on modelling deer-vehicle collision risk across Victoria was directed by Dr Casey Visintin. Chapter’s two to five are written as independent scientific publications, therefore there is some unavoidable repetition within the thesis as a whole. Minor changes have been made to the formatting of the published papers to keep style consistent within the thesis.
- Description: Doctor of Philosophy
- «
- ‹
- 1
- ›
- »