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Great Dividing Range (great + dividing_range)
Selected AbstractsBIODIVERSITY RESEARCH: Conserving macroinvertebrate diversity in headwater streams: the importance of knowing the relative contributions of , and , diversityDIVERSITY AND DISTRIBUTIONS, Issue 5 2010Amber Clarke Abstract Aim, We investigated partitioning of aquatic macroinvertebrate diversity in eight headwater streams to determine the relative contributions of , and , diversity to , diversity, and the scale dependence of , and , components. Location, Great Dividing Range, Victoria, Australia. Methods, We used the method of Jost (Ecology, 2007, 88, 2427,2439) to partition , diversity into its , and , components. We undertook the analyses at both reach and catchment scales to explore whether inferences depended on scale of observation. Results, We hypothesized that , diversity would make a large contribution to the , diversity of macroinvertebrates in our dendritic riverine landscape, particularly at the larger spatial scale (among catchments) because of limited dispersal among sites and especially among catchments. However, reaches each had relatively high taxon richness and high , diversity, while , diversity made only a small contribution to , diversity at both the reach and catchment scales. Main conclusions, Dendritic riverine landscapes have been thought to generate high , diversity as a consequence of limited dispersal and high heterogeneity among individual streams, but this may not hold for all headwater stream systems. Here, , diversity was high and , diversity low, with individual headwater stream reaches each containing a large portion of , diversity. Thus, each stream could be considered to have low irreplaceability since losing the option to use one of these sites in a representative reserve network does not greatly diminish the options available for completing the reserve network. Where limited information on individual taxonomic distributions is available, or time and money for modelling approaches are limited, diversity partitioning may provide a useful ,first-cut' for obtaining information about the irreplaceability of individual streams or subcatchments when establishing representative freshwater reserves. [source] Freshwater invasions: using historical data to analyse spreadDIVERSITY AND DISTRIBUTIONS, Issue 1 2007Sarina E. Loo ABSTRACT Aquatic invasive species cause deleterious environmental and economic impacts, and are rapidly spreading through ecosystems worldwide. Despite this, very few data sets exist that describe both the presence and the absence of invaders over long time periods. We have used Geographical Information Systems (GIS) to analyse time-series data describing the spread of the freshwater invasive New Zealand mudsnail, Potamopyrgus antipodarum, in Victoria, Australia, over 110 years. We have mapped the snail's spread, estimated the percentage of stream length invaded through time, calculated the functional form of the spread rate, and investigated the role that the two proposed vectors , fish stocking and angling , have had in this invasion. Since it was first found in 1895, P. antipodarum has expanded its range in Victoria and now occurs throughout much of the southern and central areas of the state. The north of the state is relatively less invaded than the south, with the division corresponding approximately to the presence of the Great Dividing Range. We show that the snail's range has been increasing at an approximately exponential rate and estimate that 20% of total Victorian stream length is currently invaded. We also show that using long-term data can change the outcome of analyses of the relationship between vectors of spread and invasion status of separate catchments. When our time-series data were aggregated through time, the total numbers of fish stocking events and angling activity were both correlated with invasion. However, when the time-series data were used and the number of fish stocking events calculated up until the date of invasion, no relationships with stocking were found. These results underline the role that time-series data, based on both presences and absences, have to play when investigating the spread of invasive species. [source] Pollen-based reconstructions of biome distributions for Australia, Southeast Asia and the Pacific (SEAPAC region) at 0, 6000 and 18,000 14C yr BPJOURNAL OF BIOGEOGRAPHY, Issue 9 2004Elizabeth J. Pickett Abstract Aim, This paper documents reconstructions of the vegetation patterns in Australia, Southeast Asia and the Pacific (SEAPAC region) in the mid-Holocene and at the last glacial maximum (LGM). Methods, Vegetation patterns were reconstructed from pollen data using an objective biomization scheme based on plant functional types. The biomization scheme was first tested using 535 modern pollen samples from 377 sites, and then applied unchanged to fossil pollen samples dating to 6000 ± 500 or 18,000 ± 1000 14C yr bp. Results, 1. Tests using surface pollen sample sites showed that the biomization scheme is capable of reproducing the modern broad-scale patterns of vegetation distribution. The north,south gradient in temperature, reflected in transitions from cool evergreen needleleaf forest in the extreme south through temperate rain forest or wet sclerophyll forest (WSFW) and into tropical forests, is well reconstructed. The transitions from xerophytic through sclerophyll woodlands and open forests to closed-canopy forests, which reflect the gradient in plant available moisture from the continental interior towards the coast, are reconstructed with less geographical precision but nevertheless the broad-scale pattern emerges. 2. Differences between the modern and mid-Holocene vegetation patterns in mainland Australia are comparatively small and reflect changes in moisture availability rather than temperature. In south-eastern Australia some sites show a shift towards more moisture-stressed vegetation in the mid-Holocene with xerophytic woods/scrub and temperate sclerophyll woodland and shrubland at sites characterized today by WSFW or warm-temperate rain forest (WTRF). However, sites in the Snowy Mountains, on the Southern Tablelands and east of the Great Dividing Range have more moisture-demanding vegetation in the mid-Holocene than today. South-western Australia was slightly drier than today. The single site in north-western Australia also shows conditions drier than today in the mid-Holocene. Changes in the tropics are also comparatively small, but the presence of WTRF and tropical deciduous broadleaf forest and woodland in the mid-Holocene, in sites occupied today by cool-temperate rain forest, indicate warmer conditions. 3. Expansion of xerophytic vegetation in the south and tropical deciduous broadleaf forest and woodland in the north indicate drier conditions across mainland Australia at the LGM. None of these changes are informative about the degree of cooling. However the evidence from the tropics, showing lowering of the treeline and forest belts, indicates that conditions were between 1 and 9 °C (depending on elevation) colder. The encroachment of tropical deciduous broadleaf forest and woodland into lowland evergreen broadleaf forest implies greater aridity. Main conclusions, This study provides the first continental-scale reconstruction of mid-Holocene and LGM vegetation patterns from Australia, Southeast Asia and the Pacific (SEAPAC region) using an objective biomization scheme. These data will provide a benchmark for evaluation of palaeoclimate simulations within the framework of the Palaeoclimate Modelling Intercomparison Project. [source] Genetic evidence for historical continuity between populations of the Australian freshwater fish Craterocephalus stercusmuscarum (Atherinidae) east and west of the Great Dividing RangeJOURNAL OF FISH BIOLOGY, Issue 2001D. J. McGlashan The freshwater Craterocephalus stercusmuscarum (Atherinidae) has a broad northern and south-eastern Australian distribution, and has been divided into two sub-species. Craterocephalus stercusmuscarum fulvus occurs in eastern and western flowing drainages of the southeast, while C. s. stercusmuscarum occurs in north eastern and northern flowing drainages. Four populations of each sub-species were sampled from different river systems to examine if genetic diversity was consistent with this nomenclature or a previously proposed vicariance hypothesis. Allozyme data did not support the notion that the subspecies were genetically distinct, but the mtDNA data showed that haplotypes from one sub-species, regardless of geography, were reciprocally monophyletic to haplotypes of the other subspecies. Thus, mtDNA genetic diversity was partitioned by prevailing taxonomy and the data suggest that C. s. fulvus populations in eastern and western flowing drainages may have had a relatively recent connection subsequently interrupted by geological events. [source] Using probabilistic models to investigate the disappearance of a widespread frog-species complex in high-altitude regions of south-eastern AustraliaANIMAL CONSERVATION, Issue 3 2010A. J. Hamer Abstract Amphibian populations have suffered declines and disappearances around the world. It is now recognized that many of the disappearances were the result of infection by the amphibian chytrid fungus Batrachochytrium dendrobatidis (Bd). Most global declines were first observed in the 1980s. Here, we used information from museum collections, natural-history databases and the literature to quantitatively assess the disappearance of the bell frog species complex (Litoria aurea, Litoria castanea and Litoria raniformis) in high-altitude Tableland regions of the Great Dividing Range, south-eastern Australia. Based on the sighting record, we estimated that Li. castanea disappeared on the Northern Tablelands in 1979, then from the Southern and Central Tablelands in 1984. Estimated dates of disappearance of Li. aurea and Li. raniformis from the Southern and Central Tablelands were 1981 and 1982, respectively. The Northern Tablelands populations of Li. castanea may have been one of the first high-altitude populations of frogs to disappear from Australasia and perhaps one of the first globally. We documented targeted searches of suitable habitat within the historic range of the three species in these Tableland regions since 1985, noting that only one bell frog population was discovered (Li. aurea, Southern Tablelands, 2000). Our Solow equation estimate of the probability of extant populations of bell frogs persisting up to the year 2000 was <0.001, so the rediscovery of Li. aurea was mathematically exceptional. Although the cause of these declines remains unknown, the latitudinal (i.e. north to south) and rapid pattern of disappearance of Li. castanea, and the rapid contraction in the range of Li. aurea and Li. raniformis from high-altitude regions, strongly suggests a pathogen such as Bd was responsible. We recommend further surveys for bell frogs on the Tablelands, as the rediscovery of Li. aurea provides faint hope of finding other extant populations. [source] Echinococcus granulosus in northern QueenslandAUSTRALIAN VETERINARY JOURNAL, Issue 9 20061. Prevalence in cattle Objective To determine the prevalence and geographical distribution of hydatidosis and investigate factors that might be expected to influence the prevalence of hydatids in cattle in Queensland north of the Tropic of Capricorn. To determine the effect of natural levels of infection on carcase weight and subsequent economic loss. Procedure An abattoir survey conducted in 1981 provided information on the distribution, prevalence and viability of hydatid cysts in cattle from all shires north of the Tropic of Capricorn in Queensland. Livers, lungs and spleens from 10,382 cattle were palpated at abattoirs in Cairns, Townsville and Rockhampton to detect hydatid cysts. Prevalence of infection in cattle in each shire was estimated from results of the abattoir study together with reports of infection in a further 22,185 cattle obtained from abattoir records. Linear modelling was used to define the effect of geographical origin, age, breed and sex on prevalence of infection. Differences in the weights of carcases between infected and non-infected cattle of the same age, sex, breed and property of origin were examined. The economic loss to the beef industry in the region surveyed was estimated. Results Cattle infected with hydatids originated almost entirely from regions to the east of the Great Dividing Range. The mean prevalence inside this zone was 28% compared with 3% in other areas. Viable protoscoleces were found in 0.7% of cysts. Geographical origin and age of the cattle were the most significant factors influencing prevalence. Infection with hydatids had no effect on carcase weight. Economic loss was limited to that associated with condemnations of organs at meat inspection, estimated to be $0.5 million per annum in 1981 and $6 million in 2004. The distribution of hydatids in Queensland north of the Tropic of Capricorn corresponded most closely with the distribution of small wallabies such as Macropus dorsalis (black-striped wallaby), M parryi (whiptail wallaby) and M rufogriseus (red-necked wallaby). Conclusions It was concluded that cattle are not an important part of maintaining the life-cycle of E granulosus in Queensland north of the Tropic of Capricorn. Within the endemic zone, which is almost all to the east of the Great Dividing Range, the local pattern of bovine echinococcosis is most likely to be determined by the presence or absence of small species of wallaby such as M dorsalis, M parryi and M rufogriseus. [source] | ||||||||||