Genetic monitoring reveals significant population structure in eastern quolls: implications for the conservation of a threatened carnivorous marsupial (original) (raw)
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Molecular Ecology, 1999
Tiger quolls, Dasyurus maculatus , are the largest carnivorous marsupials still extant on the mainland of Australia, and occupy an important ecological niche as top predators and scavengers. Two allopatric subspecies are recognized, D.m. gracilis in north Queensland, and D.m. maculatus in the southeast of the mainland and Tasmania. D.m. gracilis is considered endangered while D.m. maculatus is listed as vulnerable to extinction; both subspecies are still in decline. Phylogeographical subdivision was examined to determine evolutionarily significant units (ESUs) and management units (MUs) among populations of tiger quolls to assist in the conservation of these taxa. Ninety-three tiger quolls from nine representative populations were sampled from throughout the species range. Six nuclear microsatellite loci and the mitochondrial DNA (mtDNA) control region (471 bp) were used to examine ESUs and MUs in this species. We demonstrated that Tasmanian tiger quolls are reciprocally monophyletic to those from the mainland using mtDNA analysis, but D.m. gracilis was not monophyletic with respect to mainland D.m. maculatus. Analysis of microsatellite loci also revealed significant differences between the Tasmanian and mainland tiger quolls, and between D.m. gracilis and mainland D.m. maculatus. These results indicate that Tasmanian and mainland tiger quolls form two distinct evolutionary units but that D.m. gracilis and mainland D.m. maculatus are different MUs within the same ESU. The two marker types used in this study revealed different male and female dispersal patterns and indicate that the most appropriate units for short-term management are local populations. A revised classification and management plan are needed for tiger quolls, particularly in relation to conservation of the Tasmanian and Queensland populations.
Australian Journal of Zoology, 2019
The irregular nature of rainfall in the Australian arid and semiarid zones results in a heterogeneous distribution of resources in both time and space. The mammal species that reside in these regions are uniquely adapted to these climatic conditions, often occurring in naturally low densities and increasing significantly in numbers following major rainfall events. We investigated how these adaptations may influence genetic diversity and gene flow across the landscape in an endangered semiarid/arid-zone marsupial, the sandhill dunnart (Sminthopsis psammophila), from three known populations in southern Australia. Analyses of mitochondrial control region (CR) sequences and microsatellite loci revealed that S. psammophila had maintained similar levels of genetic diversity to other sympatric Sminthopsis species despite its endangered status. There was no evidence for significant phylogeographic structure within the species, but each population was genetically differentiated, based on the...
Population genetic analysis reveals a long-term decline of a threatened endemic Australian marsupial
Molecular Ecology, 2009
Since European colonization, Leadbeater's possum (Gymnobelideus leadbeateri) has declined across its range to the point where it is now only patchily distributed within the montane ash forests of the Central Highlands of Victoria. The loss of large hollowbearing trees coupled with inadequate recruitment of mature ash forest has been predicted to result in a reduction in population size of up to 90% by 2020. Furthermore, bioclimatic analyses have suggested additional reductions in the species' distribution under a variety of climate change scenarios. Using a panel of 15 highly resolving microsatellite markers and mitochondrial control region sequence data, we infer past and present gene flow. Populations in the northern part of the core range were highly admixed, and showed no signs of either current or historical barriers to gene flow. A marginal, isolated and inbred population at Yellingbo was highly genetically differentiated, both in terms of current and historic genetic structure. Sequence data confirmed the conclusions from earlier genetic simulation studies that the Yellingbo population has been isolated from the rest of the species range since before European-induced changes to the montane landscape, and formed part of a larger genetic unit that is now otherwise extinct. Historic loss of maternal lineages in the Central Highlands of Victoria was detected despite signals of immigration, indicating population declines that most probably coincided with changes in climate at the end of the Pleistocene. Given ongoing habitat loss and the recent (February 2009) wildfire in the Central Highlands, we forecast (potentially extensive) demographic declines, in line with predicted range reductions under climate change scenarios.
Molecular Ecology, 1996
Predation by the red fox Vulpes auZpes is believed to be threatening the little penguin EudyptuZa minor on Phillip Island in Victoria. Polymorphism at seven microsatellite loci was examined to estimate the extent of differentiation between Phillip Island and mainland populations of V mrlpes. Loss of alleles has occurred on Phillip Island where foxes first appeared = 88 years ago compared with mainland populations. Genetic differentiation between the Phillip Island and mainland populations was high. The relatively high differentiation found between the two populations could be due to either low migration rates, the effect of the composition of founder animals or both effects. Further ecological and historical information about the populations is needed to explore the likely significance of these effects.
Conservation Genetics, 2000
All four species of Australian quolls (Dasyurusspecies) have declined since European settlement in terms of bothrange and population numbers. Six highly polymorphic simplesequence repeats (CAn microsatellites) were used to estimate thegenetic variability and population differentiation within andamong twenty populations (including museum specimens from sixpopulations), as a preliminary means of assessing populationconservation status and relative levels of variability withinmembers of the genus. Overall mean expected heterozygosity (HE)and corrected allelic diversity (A') were highest among westernquolls. Northern quolls, eastern quolls, and tiger quolls werenot significantly different from each other in either measure. There were also significant differences in diversity amongpopulations within species. Genetic differentiation wasestimated by a number of methods and showed that themicrosatellites used here were useful for defining differencesboth among species and populations. ...
Journal of Applied Ecology, 2008
In much of the world, fauna has been adversely affected by human actions, including conversion of forests to farmland, logging and regulation of river flows. Landscape genetics data can provide information about dispersal and gene flow across the landscape, identifying barriers and facilitators of gene flow. Landscapes of central Victoria, Australia, have been altered extensively in the last 160 years. Much vegetation has been cleared or degraded, and only forest patches of mainly re-growth remain, yet some forest-dependent species like the yellow-footed antechinus Antechinus flavipes persist. The antechinus has good dispersal capabilities and is the only native, small, carnivorous mammal on most floodplains. We use antechinus as a model to understand species persistence in fragmented landscapes. 2. We analysed variation at 11 microsatellite loci and the control region of mitochondrial DNA to infer past and contemporary gene flow among A. flavipes populations. To explore genetic connectivity, we used least-cost path methods, which assign different 'friction' costs to vegetation, cleared land, roads and rivers. 3. Populations from 11 forests formed six distinct genetic groups, and with few exceptions, animals from nearby forests clustered together despite the intervening Murray River or farmland with only narrow vegetation corridors between them. 4. Genetic connectivity was aided by corridors of vegetation and inhibited by cleared land. 5. Synthesis and applications. Our approach, capitalizing on inferences on both historic and contemporary gene flow, provides management agencies with key information on metapopulation dynamics in landscapes. Rather than merely maintaining existing vegetation upon which this (and many other) species depend, the genetic information also informs where future plantings should be prioritized to facilitate demographic and genetic exchange among sub-populations of species. Moreover, the decline in condition ('health') of riparian trees in this region must be reversed by provision of flooding flows; otherwise, metapopulation dynamics will become even more disarticulated than at present.
A deep understanding of population structures and of the relationships among populations is fundamental to guarantee adequate management of endangered species. We used a molecular approach (12 microsatellite loci and mitochondrial DNA) to investigate these aspects in the woylie or brush-tailed bettong (Bettongia penicillata ogilbyi). Four distinct indigenous populations were identified in this study (i.e. Dryandra woodland and Tutanning nature reserve in the wheatbelt region and two discrete populations in the Upper Warren in the south-west forests of Western Australia). Additionally, previously undisclosed modern and historical connections between these units became evident, such as the historical connection between populations at 150 km distance (Dryandra and Upper Warren) and the contemporary gene flow between the two populations in Upper Warren (up to 60 km). Genetic attributes of the four populations were analysed and the evidence of unique genetic material in each of these populations indicated that conservation effort should aim towards the preservation of all these units. Additionally, the lower genetic diversity of the woylie population in Tutanning nature reserve prompted the need for the investigation of factors that are limiting the demographic growth of this population. This study enhances not only our knowledge about the ecology of woylies, but also the genetic consequences of habitat fragmentation and reiterates the strength and pertinence of molecular techniques in similar investigations.
Frontiers in zoology, 2016
As increasingly fragmented and isolated populations of threatened species become subjected to climate change, invasive species and other stressors, there is an urgent need to consider adaptive potential when making conservation decisions rather than focussing on past processes. In many cases, populations identified as unique and currently managed separately suffer increased risk of extinction through demographic and genetic processes. Other populations currently not at risk are likely to be on a trajectory where declines in population size and fitness soon appear inevitable. Using datasets from natural Australian mammal populations, we show that drift processes are likely to be driving uniqueness in populations of many threatened species as a result of small population size and fragmentation. Conserving and managing such remnant populations separately will therefore often decrease their adaptive potential and increase species extinction risk. These results highlight the need for a p...
Genetic structure and dispersal of red foxes (Vulpes vulpes) in urban Melbourne
Australian Journal of Zoology, 2001
This study sought to investigate the potential for gene flow and dispersal between three sampled populations of urban Melbourne foxes (Vulpes vulpes). Five highly polymorphic canine microsatellites were used to investigate the population structure of foxes. The dispersal of 14 foxes, captured and radio-collared as cubs, were monitored periodically over two years. Dispersal estimates for males and females were also calculated from published regression equations that related social group density to dispersal distance. Genetic differentiation between urban populations was greater than between more widely spaced rural populations and was also greater than that found between San Remo and Phillip Island populations, which are separated by a water barrier. A deficiency of heterozygotes was detected in the total Melbourne population, but not at any of the field sites. Mean dispersal distances after 24 months (male = 3.5 km, female = 2.0 km) compared well with published accounts of dispersal...
Genetic Consequences of Multiple Translocations of the Banded Hare-Wallaby in Western Australia
Diversity
Many Australian mammal species now only occur on islands and fenced mainland havens free from invasive predators. The range of one species, the banded hare-wallaby (Lagostrophus fasciatus), had contracted to two offshore islands in Western Australia. To improve survival, four conservation translocations have been attempted with mixed success, and all occurred in the absence of genetic information. Here, we genotyped seven polymorphic microsatellite markers in two source (Bernier Island and Dorre Island), two historic captive, and two translocated L. fasciatus populations to determine the impact of multiple translocations on genetic diversity. Subsequently, we used population viability analysis (PVA) and gene retention modelling to determine scenarios that will maximise demographic resilience and genetic richness of two new populations that are currently being established. One translocated population (Wadderin) has undergone a genetic bottleneck and lost 8.1% of its source population...