Range In Eastern Australia Research Articles

Population connectivity across east Australia's bioregions and larval duration of the range‐extending sea starMeridiastra calcar

AbstractThe diversity and distribution of marine species in eastern Australia is influenced by one of the world's strongest western boundary currents, the East Australia Current, which propels water and propagules poleward, a flow intensifying due to climate change.Population genetic structure of the asterinid sea starMeridiastra calcarwas investigated across its range in eastern Australia (12° of latitude, 2,500 km) from northern New South Wales to its poleward‐extending range in Tasmania at the southern edge influence of the East Australia Current.Population structure and connectivity ofM. calcarwere examined across six bioregions using six microsatellite loci (nuclear DNA) and the control region (mitochondrial DNA). The potential influence of the extent ofM. calcar's intertidal rock platform habitat was also assessed.Genetic structure analysis indicated that the Hawkesbury Shelf contained distinct genetic clusters, whereas the two sites in the Batemans Shelf differed from each other, with Jervis Bay Marine Park having just one genetic cluster. The Manning Shelf, Twofold Shelf, and Bruny bioregions all had similar genetic composition.Strong self‐seeding (68–98%) was indicated by microsatellite loci for all bioregions, with lower (0.3–6.5%) migration between bioregions. Poleward (New South Wales to Tasmania) migration was low except from the Manning Shelf (30%).Contemporary population connectivity and genetic structure ofM. calcarappear to be influenced by ocean currents, habitat distribution, and its short planktonic larval duration, which was a minimum of 12–14 days, depending on availability of a settlement cue.The dominance of unique genetic groups in the Hawkesbury bioregion shows the importance of this region forM. calcarand possibly a diversity of co‐distributed rock platform species. This highlights how important it is to have a large marine park in the Hawkesbury bioregion, which is presently lacking.

Historical record shows broad habitat use and rapid decline of the greater bilby Macrotis lagotis in eastern Australia

Context Understanding historical distributions of species informs their ecology and response to threats, which can support management of surviving and translocated populations. Like many critical weight-range mammals in Australia, the greater bilby (Macrotis lagotis) has experienced major declines since European colonisation. The past distribution of bilbies in eastern Australia remains uncertain owing to the rapidity of their decline, their cryptic and nocturnal nature, and the paucity of specimen records. Aims We aimed to systematically collate, geo-reference and attribute bilby records from eastern Australia to better inform their historical distribution, habitat preferences, patterns of decline and response to threats. Methods We searched explorer and early settler journals, the digitised newspaper archive, interviews with long-term residents, Aboriginal language resources and ethnographies, place and property names, unpublished datasets, and documented locations of now-inactive bilby burrows. Records were geo-referenced and attributed with date, record type, source, location precision, bioregion, habitat and local abundance. The former distribution of bilby habitat in Queensland was modelled using Maxent, and the likely former occupancy of bilbies was identified using vegetation mapping. Key results More than 250 bilby records were found, only 34 of which appear in the Atlas of Living Australia. Sixty-five per cent of the records were attributed either ‘certain’ or ‘good’ reliability. Bilbies formerly occurred over most of inland New South Wales and the southern half of Queensland in areas receiving <600 mm average annual rainfall, in a wide variety of habitats. By the 1930s, bilbies were largely restricted to their current core range in south-western Queensland. This contraction in range coincided with the northward spread of rabbits and foxes. Conclusions Bilbies had a more contiguous distribution and occupied a wider range of habitats than was previously recognised. The species persisted in apparently isolated patches to the south-east, west and north of its present distribution until the 1970s, suggesting recent declines around the peripheries of its current range. By the 1990s, bilbies occupied <3% of their pre-1900 range in eastern Australia. Implications This work details changes in bilby distribution and provides key context for interpreting contemporary survey results. It also identifies areas where further surveys are required and may assist in selecting habitat for future translocations.

The cumulative impacts of anthropogenic stressors vary markedly along environmental gradients.

Understanding the cumulative effects of multiple stressors on biodiversity is key to managing their impacts. Stressor interactions are often studied using an additive/antagonistic/synergistic typology, aimed at identifying situations where individual stressor effects are reduced or amplified when they act in combination. Here, we analysed variation in the family richness of stream macroinvertebrates in the groups Ephemeroptera, Plecoptera and Trichoptera (EPT) at 4658 sites spanning a 32° latitudinal range in eastern Australia in relation to two largely human-induced stressors, salinity and turbidity, and two environmental gradients, temperature and slope. The cumulative and interactive effect of salinity and turbidity on EPT family richness varied across the landscape and by habitat (edge or riffle) such that we observed additive, antagonistic and synergistic outcomes depending on the environmental context. Our findings highlight the importance of understanding the consistency of multiple stressor impacts, which will involve higher-order interactions between multiple stressors and environmental factors.

No evidence for cold-adapted life-history traits in cool-climate populations of invasive cane toads (Rhinella marina)

As an invasive organism spreads into a novel environment, it may encounter strong selective pressures to adapt to abiotic and biotic challenges. We examined the effect of water temperature during larval life on rates of survival and growth of the early life-history stages of cane toads (Rhinella marina) from two geographic regions (tropical vs. temperate) in the species’ invaded range in eastern Australia. If local adaptation at the southern (cool-climate) invasion front has extended the cold-tolerance of early life-stages, we would expect to see higher viability of southern-population toads under cooler conditions. Our comparisons revealed no such divergence: the effects of water temperature on rates of larval survival and growth, time to metamorphosis, size at metamorphosis and locomotor performance of metamorphs were similar in both sets of populations. In two cases where tropical and temperate-zone populations diverged in responses to temperature, the tropical animals performed better at low to medium temperatures than did conspecifics from cooler regions. Adaptation to low temperatures in the south might be constrained by behavioural shifts (e.g., in reproductive seasonality, spawning-site selection) that allow toads to breed in warmer water even in cool climates, by gene flow from warmer-climate populations, or by phylogenetic conservatism in these traits.

Searching for seadragons: predicting micro-habitat use for the common (weedy) seadragon (Phyllopteryx taeniolatus) based on habitat and prey.

Habitat associations can be critical predictors of larger‐scale organism distributions and range shifts. Here the authors consider how a critical habitat, kelp (Ecklonia radiata) and prey (mysid crustacean swarms), can influence small‐ and large‐scale distribution on the iconic common (weedy) seadragon (Phyllopteryx taeniolatus:Syngnathidae). P. taeniolatus are charismatic fish endemic to the temperate reefs of southern Australia, reported to range from Geraldton, Western Australia (28.7667°S, 114.6167°E) around southern Australia to Port Stephens, New South Wales (32.614369°S, 152.325676°E). The authors test a previously developed model of seadragon habitat preferences to predict P. taeniolatus occurrence within four sites from Sydney to the northern limit of their range in eastern Australia. They determined that P. taeniolatus associations with Ecklonia and mysid shrimp can be extrapolated across multiple sites to predict the occurrence of individual P. taeniolatus within a location/site. For instance, the authors demonstrated a significant positive relationship between the density of mysid swarms and the density of P. taeniolatus, evident across all sites despite large differences in the density of mysid swarms among sites. The findings are the first to model P. taeniolatus habitat associations across multiple sites to the northern limit of their range and have applications in protecting P. taeniolatus populations and how they may respond under climate change scenarios, such as poleward kelp retractions.

Intraspecific hybridisation of an invasive lizard on Lord Howe Island

Human-mediated dispersal of animals often acts to bring populations that have been separated for substantial periods of evolutionary time (e.g. millions of years) in their native range into contact in their introduced range. Whether these taxa successfully interbreed in the introduced range provides information on the strength of reproductive isolation amongst them. The invasive delicate skink (Lampropholis delicata) has been accidentally introduced to Lord Howe Island from four genetically divergent (>2 million years) regions of the species’ native range in eastern Australia. We used mitochondrial DNA and microsatellite data to investigate whether the individuals from four of the native-range source regions are interbreeding on Lord Howe Island. Our analyses indicate that intraspecific hybridisation among individuals from all four native-range source regions is occurring. Although there is little evidence for hybrids in the northern end of Lord Howe Island (proportion of hybrids: 0–0.02; n = 31), there is a high proportion of hybrids in the central (0.33–0.69; n = 59) and southern regions (0.38–0.75; n = 8) of the island. Given the strong evidence for interbreeding among all four native-range source regions examined, and the relatively minor morphological, life-history and phenotypic variation among them, we suggest that the delicate skink should continue to be treated as a single, widespread, but variable species.

Genetic differentiation in mountain-dwelling clam shrimp, Paralimnadia (Crustacea : Branchiopoda : Spinicaudata), in eastern Australia

The majority of Australian Spinicaudata Linder, 1945 inhabit the (semi)arid deserts of Australia’s lowlands. However, several closely related species of Paralimnadia Sars, 1896 inhabit small temporary habitats throughout the Great Dividing Range in eastern Australia. By combining analyses of mitochondrial cytochrome c oxidase subunit I (COI) with double-digest restriction-site associated DNA (ddRAD) data, we studied the species diversity and genetic diversity of this group of mountain-dwelling branchiopods. Levels of genetic differentiation in COI are relatively low between putative species (mostly between 1.5 and 6.7%), complicating COI-based species delimitation. Depending on the applied threshold, three to six species are inferred in the studied area, with most putative species being geographically restricted. Particularly notable are the high levels of population differentiation indicated by ddRAD analyses between nearby populations within putative species. This suggests that gene flow is limited, even between populations separated only by a few kilometres. This may lead to fast population differentiation, which in turn might drive speciation. Our data suggest that the species diversity of Paralimnadia in the Great Dividing Range is much higher than currently appreciated.

Towards a systematic revision of the eastern Australian land snail Austrochloritis Pilsbry, 1891 (Eupulmonata, Camaenidae): re-description of its type species, A. porteri (Cox, 1866)

Helix porteri Cox, 1866 is the type species of Austrochloritis Pilsbry, 1891, a speciose genus of camaenid land snail with a known range in eastern Australia stretching from Wilson’s Promontory in Victoria to southeastern Queensland. This species was first described based on material from two locations in New South Wales, “Upper Clarence River at Guy Faux Station” and “Upper Richmond River, at Cowlong”. These two locations are about 230 km apart from each other while all type material is considered to be lost. Comparative morpho-anatomy of specimens collected in the proximity of both type localities shows that the original concept of Helix porteri is based on two distinct species. Here we designate a neotype for this species from the Upper Richmond River area and provide a detailed redescription in order to remove any ambiguity about the identity of Austrochloritis porteri. Material from the vicinity of the second site mentioned in the original description of H. porteri, Guy Fawkes Station, is identified as Austrochloritis speculoris Shea & Griffiths, 2010. We describe key diagnostic features distinguishing both species.

Evidence of behavioural thermoregulation by dugongs at the high latitude limit to their range in eastern Australia

Many species of marine mammals have evolved behavioural adaptations to minimize heat loss to the surrounding water. We tracked 21 dugongs (Dugong dugon Müller 1776) using acoustic and satellite/GPS transmitters in 2012, 2013 and 2014 in Moreton Bay, Queensland at the high latitude limit of the species' winter range in eastern Australia to examine if there was a relationship between movements and environmental temperature that might suggest behavioural thermoregulation. Oceanic waters immediately outside the bay where the dugong's seagrass food is unavailable exhibited temperatures from 5.5 °C warmer to 3 °C cooler than the Eastern Banks, the major dugong habitat in the bay. All tracked dugongs made at least one (and up to 66) return trip(s) from the Eastern Banks to the adjacent oceanic waters. The probability of making an outgoing trip was highest in 2014 and lowest in 2013 when the water temperature inside the bay was higher than the other two years. The odds of making an outgoing trip were lower when temperature differences (outside minus inside) were small or negative but increased by a factor of up to 2.12 for each 1 °C positive difference. Individual dugongs were most likely to travel out of the bay between midnight and noon on an outgoing tide or at slack high water and return to the bay on an incoming tide or slack low water between noon and midnight. The amount of time a dugong spent outside the bay on each trip was relatively short with an overall median of 5.9 h. The dugongs' individual activity spaces generally declined as winter progressed suggesting a change in the cost-effectiveness of moving outside the bay. Our analysis adds to the evidence that dugongs undertake behavioural thermoregulation at least at the high latitude limits of their range.

Discovered and disappearing? Conservation genetics of a recently named Australian carnivorous marsupial.

Five new species within the Australian carnivorous marsupial genus Antechinus have recently been named, at least two of which are threatened. Important facets of the habitat use and extinction risk of one of these new species, the buff‐footed antechinus, A. mysticus, are not well understood. Previous research has suggested that the species utilizes a broad range of inter‐connected forest habitats in southeast Queensland (Qld), Australia. Based on this potentially connected habitat, we predicted that A. mysticus should have low population genetic structure, particularly in relation to its congener, the spatially restricted, high altitude, closed‐forest A. subtropicus. We genotyped nine microsatellite loci for six populations of A. mysticus, sampled throughout their known range in eastern Australia, and compared them with four proximate populations of A. subtropicus. Surprisingly, genetic structuring among southeast Qld populations of A. mysticus was moderate to high and similar to that between A. subtropicus populations. We postulate that all A. mysticus populations have declined recently (<100 generations), particularly the northernmost southeast Qld population, which may be at risk of extinction. Our results suggest that A. mysticus is limited to a more scattered and fragmented distribution than previously thought and may be in decline. The identification of population decline in this study and recently in other Antechinus suggests the extinction risk of many Australian mammals should be reassessed.

Calling phenology and detectability of a threatened amphibian (Litoria olongburensis) in ephemeral wetlands varies along a latitudinal cline: Implications for management

AbstractAmphibian reproductive biology and activity are highly sensitive to environmental cues. For amphibian conservation in the face of climate change, a clear priority is to investigate impacts of variable weather on breeding activity and detectability. This study assessed variation in the phenology, intensity and detectability of calling for a threatened temporary wetland breeding species, Litoria olongburensis. Acoustic and visual surveys were conducted monthly from August 2009 to July 2011 over the species latitudinal range in eastern Australia. Calling phenology of L. olongburensis varied spatially and temporally within and among latitudinal clusters. Detectability of frogs also varied among months and transects, and also with the type of survey conducted (visual vs. acoustic). Air temperature was a strong predictor for the onset of the calling season (early spring); however, peaks in calling abundances were primarily driven by monthly accumulated rainfall. The duration of the calling season varied among latitudinal clusters, becoming narrower moving south, reflecting clinal variation in weather patterns. This study presents a framework for amphibian species management using a combination of survey techniques and the climatic conditions influencing detectability. Applied along the latitudinal gradient, it provides data for predicting the likely impacts of climate change on amphibian activity and reproduction.

Multiple introductions from multiple sources: invasion patterns for an important Eucalyptus leaf pathogen.

Many population studies on invasive plant pathogens are undertaken without knowing the center of origin of the pathogen. Most leaf pathogens of Eucalyptus originate in Australia and consequently with indigenous populations available, and it is possible to study the pathways of invasion. Teratosphaeria suttonii is a commonly occurring leaf pathogen of Eucalyptus species, naturally distributed in tropical and subtropical regions of eastern Australia where it is regarded as a minor pathogen infecting older leaves; however, repeated infections, especially in exotic plantations, can result in severe defoliation and tree deaths. Nine polymorphic microsatellite markers were used to assess the genetic structure of 11 populations of T.suttonii of which four where from within its native range in eastern Australia and the remaining seven from exotic Eucalyptus plantations. Indigenous populations exhibited high allele and haplotype diversity, predominantly clonal reproduction, high population differentiation, and low gene flow. The diversity of the invasive populations varied widely, but in general, the younger the plantation industry in a country or region, the lower the diversity of T.suttonii. Historical gene flow was from Australia, and while self-recruitment was dominant in all populations, there was evidence for contemporary gene flow, with South Africa being the most common source and Uruguay the most common sink population. This points distinctly to human activities underlying long-distance spread of this pathogen, and it highlights lessons to be learned regarding quarantine.

How does embryonic and larval thermal tolerance contribute to the distribution of the sea urchin Centrostephanus rodgersii (Diadematidae) in New Zealand?

Sea surface temperature (SST) influences the physiology of marine invertebrates, and, in turn, their geographical distribution. The Diadematidae sea urchin Centrostephanus rodgersii has expanded its range in Eastern Australia as a result of increased winter sea temperatures, and there is interest in the potential for the species to increase its range and abundance in New Zealand. We investigated the extent to which embryonic and larval thermal tolerance of fertilization, cleavage, hatching, gastrulation and appearance of plutei may control the distribution of the adult populations in New Zealand. We also compared these individuals with an Australian population in northern New South Wales at Coffs Harbour from a region just north of where the Eastern Australian Current gives rise to the Tasman Front current to New Zealand. The aim of the present study was to find evidence for adaptation in fertilization and the developmental stages to New Zealand winter sea temperatures. Fertilization was not affected by temperature over a broad thermal range (12.0°C–26.4°C and 12.8°C–29.5°C for the New Zealand and the Coffs Harbour population respectively). The first cleavage, hatching, gastrulation and appearance of plutei were more sensitive to temperature and occurred within a well-defined thermal window (17.2°C–23.5°C in New Zealand and 17.3°C–24.5°C in Coffs Harbour). The sites where C. rodgersii adults have been reported in New Zealand lie on the 15°C winter isotherm, consistent with our findings with regard to the lower temperature for pluteal development for the New Zealand population. We found evidence for a shift in thermal tolerance between the two populations of C. rodgersii examined, with fertilization and each developmental stage showing an upper thermal limit consistently shifted by ≈1°C towards lower temperatures in New Zealand individuals. Our findings indicate that the thermal window for larval development of C. rodgersii may contribute to its present distribution in New Zealand. In addition, given that larval development in New Zealand presently occurs at the colder limit of the thermal window of C. rodgersii, there may be the potential for a future expansion of its distributional range under future ocean warming scenarios.

Genetic diversity of subgroup 1 ilarviruses from eastern Australia

This is the first report of the genetic diversity within ilarvirus subgroup 1 from eastern Australia. It supports the separation of tobacco streak virus (TSV) strains from parthenium (Parthenium hysterophorus) and crownbeard (Verbescina encelioides) based on serology and host specificity. It has confirmed one previously described strain of TSV as a member of the species Strawberry necrotic shock virus and another as a new subgroup 1 ilarvirus, ageratum latent virus (AgLV), from Ageratum houstonianum. A multiplex RT-PCR showed that the genetically distinct strains of TSV and AgLV were commonly found in symptomless infections in virus-specific alternative weed hosts growing over a wide geographical range in eastern Australia. TSV has been one of the most damaging viruses in Australian oilseed and pulse crops in recent years, and this study has provided the taxonomic knowledge essential for the development of control programs for these viruses.

Growth, morphometrics and size structure of the Diadematidae sea urchin Centrostephanus rodgersii in northern New Zealand

The sea urchin Centrostephanus rodgersii has increased its range in Eastern Australia resulting in important ecological changes. C. rodgersii may also have expanded its distribution range to northern New Zealand in the last five to six decades, although little is known about this process and of the biology of the species in New Zealand. We investigated morphometrics as well as growth using two techniques (growth line count in genital plates and tag–recapture using the fluorescent marker tetracycline). These methods allowed modelling of size at age of C. rodgersii in New Zealand, which we compared with populations recently established in Tasmania. The modelled growth rate was only slightly higher in the New Zealand population, and no differences in morphometrics were observed. The New Zealand population structure suggests that annual recruitment occurs regularly, with the population including a range of ages (3 to 10+ years).

Does nest box design influence use by the eastern pygmy-possum?

Managing the availability of shelter sites is central to the conservation of vertebrate wildlife dependent on tree hollows (cavities) because hollow abundance has been reduced in many landscapes and trees do not typically acquire hollows until they are at least 100 years old. Artificial hollows (nest boxes) provide one option to offset local shortages in tree hollows. However, knowledge of preferred designs is required for this to be effective. We investigated nest box preference by the eastern pygmy-possum (Cercartetus nanus), a small marsupial recognised as threatened across part of its geographic range in eastern Australia. We installed nest boxes of four different designs in each of 30 plots where tree hollows were scarce. Designs showed no significant difference in thermal profile. We captured 223 adult and subadult pygmy-possums within 78% of the 120 boxes. Breeding females used boxes more frequently than adult males and showed a preference among the designs whereas males did not. Females favoured plywood nest boxes over a PVC design offering a horizontal cavity. Use of the PVC design increased when repositioned to present a vertical cavity. Thus, breeding females are selective of the cavities used to rear young, which may limit local population size.

Home Range of the Australian Squirrel Glider, Petaurus norfolcensis (Diprotodontia)

Knowledge of the home range of threatened species is basic to their management and conservation. We describe the home range of the squirrel glider (Petaurus norfolcensis), a threatened marsupial, in the central part of its geographic range in eastern Australia. Thirteen individuals belonging to 6 monogamous social groups were radiotracked for 2–9 months. The adaptive kernel (AK95%) estimate reached an asymptote at approximately 30 locations, giving a mean area of 6.2 ha 6 0.6 SE for the 9 gliders with .30 locations. The AK50% averaged 0.9 6 0.2 ha, indicating that small core parts of the home range were used intensively. Home ranges of group members (AK95%) showed a high degree of overlap (77%) and when combined averaged 6.7 6 1.0 ha. They overlapped substantially (50%) with adjacent glider groups but core areas (AK50%) within them overlapped by only 12%. Two of 5 available habitats were well represented in all group home ranges. Habitat dominated by coast banksia (Banksia integrifolia), a key winter nectar food resource, was overrepresented compared to its availability. Conservation measures for this species involving habitat retention or restoration must be informed by recognition of what comprises a preferred local habitat and its distribution.

Pterostylis nutans (Orchidaceae) has a specific association with two Ceratobasidium root-associated fungi across its range in eastern Australia

In this study, we have identified the root-associated fungi of a common species of terrestrial orchid across its range in eastern Australia. We have amplified and cloned fungal ITS DNA extracted from roots of 15 Pterostylis nutans R. Br. plants from six separate geographic localities. Sequencing and GenBank comparison demonstrated two species of Ceratobasidium fungi as the main fungal partners of the orchid. Uncommon fungal associates included homobasidiomycete species such as a Gymnomyces sp. and a Tricholoma sp., Leptodontidium orchidicola, and an unidentified soil fungus. These results demonstrate that specificity for fungal partners occurs in P. nutans and reinforces the idea that conservation measures for endangered Australian orchids must include ex situ perpetuation of fungal symbionts as well as plant material.

Determinants of preferred intertidal feeding habitat for Eastern Curlew: A study at two spatial scales

Abstract Broadscale habitat use by Eastern Curlews (Numenius madagascariensis) in their non‐breeding range in eastern Australia was assessed using low tide surveys on feeding grounds, where 60 skilled volunteers made repeated counts of the birds on intertidal flats, across 41% (9500 ha) of the intertidal habitat within Moreton Bay, Australia. We analysed 32 defined sections of intertidal flat, of roughly equal area (mostly 200–400 ha), which varied greatly in their curlew density (2–47 birds per 100 ha) and also in substrate and other environmental features. Sites with the least resistant substrates had densities three times those with the most resistant substrates. Of 10 environmental characteristics measured for each site, substrate resistance was the best predictor of curlew density (r2 = 0.45). Characteristics that were poor predictors included distance to the nearest roost, level of human disturbance and distance to urban settlement. For a finer‐scale assessment, microhabitat use and feeding behaviour were recorded during low tide within 12 intertidal flats, which varied in size (23–97 ha), substrate, topography and other features. Across all flats, curlews strongly preferred to feed relatively close (0–50 m) to the low‐water line. They fed on a variety of substrates (including sand, sandy‐mud, mud and seagrass) in broadly similar proportions to their occurrence in the habitat. There was a statistically significant preference for sand, although its magnitude was not strong. These results indicate that curlews select habitat most strongly at a between‐flat rather than within‐flat scale.

&lt;i&gt;Pterostylis nutans&lt;/i&gt; (Orchidaceae) has a specific association with two &lt;i&gt;Ceratobasidium&lt;/i&gt; root-associated fungi across its range in eastern Australia

In this study, we have identified the root-associated fungi of a common species of terrestrial orchid across its range in eastern Australia. We have amplified and cloned fungal ITS DNA extracted from roots of 15 Pterostylis nutans R. Br. plants from six separate geographic localities. Sequencing and GenBank comparison demonstrated two species of Ceratobasidium fungi as the main fungal partners of the orchid. Uncommon fungal associates included homobasidiomycete species such as a Gymnomyces sp. and a Tricholoma sp., Leptodontidium orchidicola, and an unidentified soil fungus. These results demonstrate that specificity for fungal partners occurs in P. nutans and reinforces the idea that conservation measures for endangered Australian orchids must include ex situ perpetuation of fungal symbionts as well as plant material.