School of BioSciences - Research Publications
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ItemContrasting patterns of population connectivity between regions in a commercially important mollusc Haliotis rubra: integrating population genetics, genomics and marine LiDAR data(WILEY, 2016-08)Estimating contemporary genetic structure and population connectivity in marine species is challenging, often compromised by genetic markers that lack adequate sensitivity, and unstructured sampling regimes. We show how these limitations can be overcome via the integration of modern genotyping methods and sampling designs guided by LiDAR and SONAR data sets. Here we explore patterns of gene flow and local genetic structure in a commercially harvested abalone species (Haliotis rubra) from southeastern Australia, where the viability of fishing stocks is believed to be dictated by recruitment from local sources. Using a panel of microsatellite and genomewide SNP markers, we compare allele frequencies across a replicated hierarchical sampling area guided by bathymetric LiDAR imagery. Results indicate high levels of gene flow and no significant genetic structure within or between benthic reef habitats across 1400 km of coastline. These findings differ to those reported for other regions of the fishery indicating that larval supply is likely to be spatially variable, with implications for management and long-term recovery from stock depletion. The study highlights the utility of suitably designed genetic markers and spatially informed sampling strategies for gaining insights into recruitment patterns in benthic marine species, assisting in conservation planning and sustainable management of fisheries.
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ItemA species in decline: genetic diversity and conservation of the Victorian eastern barred bandicoot, Perameles gunnii(SPRINGER, 2013-12)The eastern barred bandicoot, Perameles gunnii, has undergone a dramatic decline in distribution and abundance on the mainland of Australia during the twentieth century. In 1988 a captive breeding program was initiated to reduce the chance of extinction. With the extinction of the last wild mainland population in the early 1990s, reintroductions from captive-bred P. gunnii have met limited success, and currently only two extant populations persist in predator proof enclosures in the State of Victoria. With ~20� years of breeding, there are concerns that the genetic diversity within the breeding program has declined and may inhibit current and future success of the program. We have used ten nuclear microsatellite loci and sequencing of two partial mitochondrial genes (cytochrome oxidase I and ATPase 6) to determine genetic diversity within current Victorian P. gunnii. These diversity estimates are compared with historic samples from the captive breeding program dating back to 1995, historic samples from the last wild mainland population found at Hamilton in 1992 and contemporary Tasmanian wild populations. Results indicate that the captive P. gunnii population in the State of Victoria has lost significant genetic diversity through time. Genetic diversity is also reduced in populations at Hamilton Community Parklands and Mount Rothwell. Samples from the last wild population at Hamilton collected in 1992, along with samples from Tasmanian P. gunnii, had significantly greater genetic diversity than contemporary mainland populations. The results are discussed with reference to management options for maintaining genetic diversity within Victorian P. gunnii, including crossing Victorian and Tasmanian P. gunnii to increase genetic diversity, adaptability and evolutionary potential.
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ItemThe development of 10 novel polymorphic microsatellite markers through next generation sequencing and a preliminary population genetic analysis for the endangered Glenelg spiny crayfish, Euastacus bispinosus(SPRINGER, 2013-07)The Glenelg spiny crayfish, Euastacus bispinosus, is an iconic freshwater invertebrate of south eastern Australia and listed as 'endangered' under the Environment Protection and Biodiversity Conservation Act 1999, and 'vulnerable' under the International Union for Conservation of Nature's Red List. The species has suffered major population declines as a result of over-fishing, low environmental flows, the introduction of invasive fish species and habitat degradation. In order to develop an effective conservation strategy, patterns of gene flow, genetic structure and genetic diversity across the species distribution need to be clearly understood. In this study we develop a suite of polymorphic microsatellite markers by next generation sequencing. A total of 15 polymorphic loci were identified and 10 characterized using 22 individuals from the lower Glenelg River. We observed low to moderate genetic variation across most loci (mean number of alleles per locus = 2.80; mean expected heterozygosity = 0.36) with no evidence of individual loci deviating significantly from Hardy-Weinberg equilibrium. Marker independence was confirmed with tests for linkage disequilibrium, and analyses indicated no evidence of null alleles across loci. Individuals from two additional sites (Crawford River, Victoria; Ewens Ponds Conservation Park, South Australia) were genotyped at all 10 loci and a preliminary investigation of genetic diversity and population structure was undertaken. Analyses indicate high levels of genetic differentiation among sample locations (F ST = 0.49), while the Ewens Ponds population is genetically homogeneous, indicating a likely small founder group and ongoing inbreeding. Management actions will be needed to restore genetic diversity in this and possibly other at risk populations. These markers will provide a valuable resource for future population genetic assessments so that an effective framework can be developed for implementing conservation strategies for E. bispinosus.