Sminthopsis Murina Research Articles

Seasonal consumption of mycorrhizal fungi by a marsupial-dominated mammal community

The temperate forests of Australia support a high diversity of hypogeous fungi and a wide variety of mycophagous mammals, yet many mammal-fungal relationships are still poorly understood. We studied the seasonal fungal diets of eight sympatric mammals (seven marsupials and one rodent) in a remnant montane eucalypt forest. Fifty-five different fungal taxa were identified from 305 scat samples. Swamp wallabies (Wallabia bicolor), yellow-footed antechinus (Antechinus flavipes) and brown antechinus (A. stuartii) were the primary mycophagists in this community, but all mammals consumed fungi, including three species not previously recorded as mycophagous (eastern grey kangaroo, Macropus giganteus;common wallaroo, Osphranter robustus; and common dunnart, Sminthopsis murina). Winter was the peak season for fungal consumption and dietary diversity of fungi, however, the diversity of taxa ingested varied between species and season. Our work supports the idea that a diverse mycophagous mammal community is important for maintaining natural variation in fungal community composition.

Niche conservatism and phylogenetic clustering in a tribe of arid-adapted marsupial mice, the Sminthopsini.

The progressive expansion of the Australian arid zone during the last 20Ma appears to have spurred the diversification of several families of plants, vertebrates and invertebrates, yet such taxonomic groups appear to show limited niche radiation. Here, we test whether speciation is associated with niche conservatism (constraints on ecological divergence) or niche divergence in a tribe of marsupial mice (Sminthopsini; 23 taxa) that includes the most speciose genus of living dasyurids, the sminthopsins. To that end, we integrated phylogenetic data with ecological niche modelling, to enable us to reconstruct the evolution of climatic suitability within Sminthopsini. Niche overlap among species was low-moderate (but generally higher than expected given environmental background similarity), and the degree of phylogenetic clustering increased with aridity. Climatic niche reconstruction illustrates that there has been little apparent evolution of climatic tolerance within clades. Accordingly, climatic disparity tends to be accumulated among clades, suggesting considerable niche conservatism. Our results also indicate that evolution of climatic tolerances has been heterogeneous across different dimensions of climate (temperature vs. precipitation) and across phylogenetic clusters (Sminthopsis murina group vs. other groups). Although some results point to the existence of shifts in climatic niches during the speciation of sminthopsins, our study provides evidence for substantial phylogenetic niche conservatism in the group. We conclude that niche diversification had a low impact on the speciation of this tribe of small, but highly mobile marsupials.

A note on detection of the Common Dunnart Sminthopsis murina (Dasyuromorphia: Dasyuridae) using artificial shelter objects as a survey technique

The widespread Common Dunnart Sminthopsis murina is typically only infrequently found during trapping studies. Pitfall trapping is generally considered a more reliable trapping method for dunnarts than Elliott-type box traps, but is often time consuming and labour-intensive. This short paper documents incidental records of S. murina detected using artificial shelter objects established during herpetofauna surveys in the Pilliga forest, in northern inland New South Wales, and discusses the potential value of this survey technique as a complement to conventional trapping methods when conducting surveys for dunnarts

Spermatozoa of Sminthopsis murina (Mammalia: Metatheria) exhibit an unusually high degree of chromatin stability in the absence of disulphide bonding in protamine 1.

Although all but a single genus (Planigale) of the metatheria so far examined contain no cysteine residues in protamine 1, we report a remarkable level of chromatin stability in the spermatozoa of the common dunnart, Sminthopsis murina. S. murina cauda epididymal spermatozoa and somatic epithelial cells were exposed to a combination of graded treatments to lyse sperm protein and induce sperm DNA damage via standard freeze-thaw protocols and post-thaw incubation at 37°C for 48h, exposure to sodium nitroprusside (SNP) and the enzyme AluI restriction endonuclease. Sperm DNA fragmentation was assessed using the comet assay and sperm chromatin dispersal test. Although S. murina somatic cells showed DNA fragmentation following protein lysis and after treatment with all the protocols specifically designed to induce chromatin damage, sperm DNA fragmentation was only observed following moderate to severe proteolytic exposure and treatment with the restriction endonuclease; there was also an increase in the baseline halo of spermatozoa treated with an aggressive reducing agent, but no corresponding evidence of fragmented DNA, suggesting that cysteine residues may be functioning to conform tertiary and/or quaternary chromatin structure. Given that the protamine 1 of S. murina contains no cysteine, we suggest that the source of these residues is possibly the histone fraction of the chromatin and that the high level of stability is potentially related to prolonged sperm survival in the female's reproductive tract.

Refuge sites, activity and torpor in wild common dunnarts (Sminthopsis murina) in a temperate heathland

This telemetric study describes patterns of movement, activity, refuge-site use and torpor in free-living Sminthopsis murina over one autumn/winter period in a warm-temperate habitat. S. murina were found to rest during the day in burrows and hollow logs. Individuals maintained several daytime refuges and foraged over several hectares each night. They were found to prefer agamid burrows where a daily temperature of 10.3–15.8°C was maintained when ambient surface temperatures varied between 3.5 and 24.6°C. Torpor was employed in 12 of 13 complete resting periods recorded. Dunnarts were found to use both long (>6 h) and short (<4 h) torpor bouts with a minimum skin temperature of 17.2–26.7°C. Typically, torpor occurred in the morning, though bouts into the afternoon were also recorded. Arousal rates from torpor were variable and were achieved by endogenous and passive means. Normothermic rest bouts tended to be short (mostly <3 h) though longer periods were recorded, with a mean resting skin temperature of 32.3 ± 0.8°C. The variable physiological responses observed in S. murina seem to follow a facultative pattern, and, along with long activity periods and their use of refuge sites, may be linked to variable invertebrate activity during cooler months.

Differential habitat use by a local population of subadult common dunnarts, Sminthopsis murina, following wildfire in coastal wet heath, New South Wales, Australia

Little has been published about Sminthopsis murina, a small insectivorous marsupial encountered infrequently during trapping studies. Individuals favour vegetation associations found in recently burnt heathlands and forests; however, individuals rarely remain in such areas long enough for repeated capture. We report an unusual occurrence of habitat fidelity by a dense population of subadult S. murina in coastal wet heath, New South Wales, Australia. Individuals were captured repeatedly in the first 16 months following wildfire (30 subadults trapped 154 times: recapture rate = 80%). Densities peaked 10 months after fire at 3.75 individuals ha–1. More males than females were captured (23 males, 7 females). Habitat analyses revealed differential use of regenerating coastal wet heathland by S. murina. Significantly more captures were made in areas of high soil moisture in the first six months following fire. Captures then decreased in these areas but increased where soil moisture had been lower and where vegetation had been growing more slowly. Beyond the 1995/96 breeding season, regenerating vegetation became increasingly dense and less patchy and captures of S. murina ultimately declined to zero. This paper records a rare opportunity to examine habitat preferences of a single cohort of subadult S. murina. Habitat use may have been determined by the presence of a narrow range of vegetation structure.

Foraging behaviour and habitat use by Antechinus flavipes and Sminthopsis murina (Marsupialia: Dasyuridae) in response to predation risk in eucalypt woodland

We examined the foraging behaviour and habitat use of two species of small Australian mammal ( Antechinus flavipes and Sminthopsis murina) in response to predation risk in remnant eucalypt woodland. Predation risk was manipulated by providing refuge in the form of ground level wire netting to reduce risks from avian and mammalian predators. Giving-up-densities (GUD) using artificial food trays (20 mealworms in 1.5 l vermiculite) quantified the foraging behaviour in response to predation risk, by measuring the quitting harvest rate. Both A. flavipes and S. murina had lower GUDs (number of mealworms remaining) under the netting than in the open, most likely because these areas have lower predation risk. Animals also made greater visits to tracking tunnels under the netting compared to in the open. Tracking animal movements using fluorescent pigments also revealed preference for natural microhabitats that were structurally complex with animals moving most where logs and rock crevices were present. These results suggest that small mammals may use habitat structure to reduce their risks of predation. If future studies are able to demonstrate commensurate population-level responses, manipulation of habitat may be a useful management option to complement the direct control of exotic predators such as foxes and feral cats.

Small dasyurid marsupials - are they effective pollinators?

The evidence that several species of dasyurid marsupial commonly visit flowers and therefore act as pollinators is reviewed. Three species of Antechinus have frequently been trapped visiting flowering banksias. Several studies provide compelling evidence that Antechinus stuartii is an effective pollinator. It was recorded visiting flowering banksias at eight locations, where it carried abundant pollen on its snout and in its faeces. At one site, regular flower visitation was demonstrated by automated photography and by spool-and-line tracking. Pollen load data for Sminthopsis murina and Sminthopsis griseoventer suggest that these species may also act as pollinators. Evidence for pollination by Phascogale tapoatafa is anecdotal but studies at three locations report extended bouts of nectar feeding, and heavy pollen loads were directly observed at one site. Some 38 plant species are known to be visited by 10 dasyurid species, with 4–10 plant species being visited by each of five dasyurid species. These observations suggest that several species of dasyurid are likely to be important pollinators. Further studies are needed to clarify the extent of their role. This review highlights the types of data that should be sought.

Sminthopsis griseoventer boullangerensis (Marsupialia:Dasyuridae), a new subspecies in the S. murina complex from Boullanger Island, Western Australia

A new subspecies from the Sminthopsis murina complex, Sminthopsis griseoventer boullangerensis, subsp. nov., is described from Boullanger Island, off the coast of Western Australia. This subspecies was considered previously to be identical to S. griseoventer griseoventer, which is common on the mainland of south-western Western Australia, but differs from it with fixed differences at three of 18 isozymes screened. It also differs from S. griseoventer griseoventer in having a relatively longer tail and no entoconids on the second and third molars, and being completely separated from it in a canonical variates analysis. It has not been given full species status as it differs very little in mitochondrial DNA control region sequences from S. griseoventer griseoventer. It differs from other members of the S. murina complex in its grey ventral pelage, distinctive tail morphology, relatively small palatal vacuities (with correspondingly greater inter-palatal vacuity distance), relatively larger bullae, and more brachycephalic skull. Sminthopsis griseoventer boullangerensis has a small population and extremely limited known distribution, and is considered endangered. Potential threats include competition from a high-density population of house mice on Boullanger Island, the possibility of fires and feral predators being introduced to the island, and the increased risk of stochastic extinction that is consequent on small population size.

The modified primary succession following sand mining: A validation of the use of chronosequence analysis

AbstractChanges in small mammal succession along a forested coastal dune system in the Myall Lakes‐National Park, New South Wales, during 15 years of regeneration after sand mining, were determined by surveys in 1982 and 1987. The results clearly demonstrate a wave of succession moving along the mining path, and confirm that over the intervening 5 year period to 1987, small mammal succession has followed a path indicated by that of the 1982 chronosequence. The house mouse, Mus musculus quickly recolonizes disturbed areas, and peak abundance occurred on plots with a regeneration age of 3.7 years in 1982 and 3.4 years in 1987 (i.e. the 3.0–4.5 age class). Colonization by the New Holland mouse. Pseudomys novaehollandiae was first recorded on plots with 4.6 years regeneration in 1982 and 5.4 years in 1987. Peak Pseudomys numbers occurred on plots in the 7.5–9.0 age class in both 1982 and 1987. The common dunnart, Sminthopsis murina appears to be the third species to enter the succession. This modified primary succession closely resembles the mammalian secondary succession following fire where additional evidence suggests that the use of chronosequence analysis may also be appropriate.

Correlates of torpor in the insectivorous dasyurid marsupial Sminthopsis murina.

Body temperatures, oxygen consumption and the thermal response of liver mitochondrial membranes of the Common Dunnart, Sminthopsis murina, were measured during winter and the summer mating season. In winter body temperatures for S. murina during spontaneous torpor were as low as 15oC and oxygen consumption was reduced to 6% of normothermic resting animals. In summer animals remained normothermic. For the winter animals liver mitochondrial succinate oxidase and succinate: cytochrome c reductase showed a constant apparent Arrhenius activation energy (Ea) over the temperature range 6 to 40oC. For summer animals Ea increased below about 20oC. The temperature coefficient for the motion of spin labels intercalated with membrane lipids increased below about 8oC for membranes from winter animals and below 20oC for summer animals.

SIX NEW AUSTRALIAN CHIGGERS (ACARI: TROMBICULIDAE)

Abstract Neotrombicula greenlyi sp.n. is described from a gecko, Phyllodactylus marmoratus (Gray) (Lacertilia: Gekkonidae), in South Australia. Guntheria shareli sp.n. is described from a pademelon, Thylogale stigmatica Gould (Marsupialia: Macropodidae), and a bush‐rat, Rattus fuscipes coracius (Thomas) (Rodentia: Muridae), in north Queensland; G. platalea sp.n. from R. f. fuscipes (Waterhouse) in south‐west Western Australia; and G. salmleni sp.n. from a dunnart, Sminthopsis murina (Waterhouse) (Marsupialia: Dasyuridae), in an unspecified locality. Schoutedenichia empusa and S. mimema spp.n. are described from a rock‐rat, Zyzomys woodwardi (Thomas) (Muridae), in the Kimberley, Western Australia.

Electrophoretic Resolution of Species Boundaries in the Sminthopsis murina Complex (Dasyuridae)

Isozyme electrophoresis of 30 loci was used to characterize 52 individuals in 20 populations of the Sminthopsis murina complex. The populations fell into six groups within which there was genetic uniformity but among which there were extensive differences. These groups correspond to the species S. murina, S. ooldea, S. leucopus, S. dolichura, S. gilberti and S. caniventer.

Small mammal responses to pyric successional changes in eucalypt forest

Sixteen 1-ha study plots covering five regeneration stages were simultaneously trapped five times over a 20-month period to provide data on small mammal response to vegetation changes following fire. Areas regenerating after fires from 9 years to 1 month before the investigation were sampled in a uniform open forest on a coastal sand plain. Two types of understorey were recognized: one dominated by true forest shrubs with which Rattus fuscipes, Antechinus stuartii and Sminthopsis murina were associated, and another dominated by heath elements where the addition of Pseudomys novaehollandiae and Mus musculus produced a significantly more diverse small mammal community. The two communities exhibited different responses to post-fire vegetation changes. Rattus fuscipes was the most abundant species and showed a logistic growth in biomass. No resident populations were established in the first 3 years, but a rapid increase in biomass occurred from 3 to 5 years to plateau after 8 years. Regeneration age had the greatest effect on R. fuscipes biomass mediated through the amount of accumulated leaf litter with additional variation being attributed to several vegetation structure variables and plant species diversity. A replacement sequence in time was observed for species reaching their maximum abundance (P. novaehollandiae and/or M. musculus → S. murina → A. stuartii → R. fuscipes) and was interpreted as species occupying stages in the succession when their optimal habitat requirements were fulfilled. These results have important implications for the design of management policies using fire or fire regimes as tools for habitat maintenance or alteration. A mosaic of forest patches of adequate size covering the entire range of seral stages is necessary to meet the optimum requirements of all the above species.

THE SPINOSA SPECIES-GROUP, GENUS BOOPIA PIAGET (PHTHIRAPTERA: BOOPIIDAE)*

Four new species belonging to the Boopia spinosa species-group parasitic on Australian Dasyuridae are described: B. greeni, type-host Antechinus minimus (Geoffroy); B. murrayi, type-host Antechinus swainsonii (Waterhouse); B. aquilonia, type-host Antechinus bellus (Thomas); and B. lukoschusi, type-host Sminthopsis murina (Waterhouse). The characters within the group are considered and some remarks included on the possible relationships of the species and their hosts. The correct interpretation of Harrison and Johnston's original description of B. brevispinosa is discussed.