David Paull

Genetic analysis of a chromosomal hybrid zone in the Australian morabine grasshoppers (Vandiemenella, Viatica species group).

Whether chromosomal rearrangements promote speciation by providing barriers to gene exchange between populations is one of the long-standing debates in evolutionary biology. This question can be addressed by studying patterns of gene flow and selection in hybrid zones between chromosomally diverse taxa. Here we present results of the first study of the genetic structure of a hybrid zone between chromosomal races of morabine grasshoppers Vandiemenella viatica, P24(XY) and viatica17, on Kangaroo Island, Australia. Chromosomal and 11 nuclear markers revealed a narrow hybrid zone with strong linkage disequilibrium and heterozygote deficits, most likely maintained by a balance between dispersal and selection. Widths and positions of clines for these markers are concordant and coincident, suggesting that selection is unlikely to be concentrated on a few chromosomes. In contrast, a mitochondrial marker showed a significantly wider cline with centre offset toward the P24(XY) side. We argue that the discordance between the mitochondrial and nuclear/chromosomal clines and overall asymmetry of the clines suggest a secondary origin of the contact zone and potential movement of the zone after contact. Genome-wide scans using many genetic markers and chromosomal mapping of these markers are needed to investigate whether chromosomal differences directly reduce gene flow after secondary contact.

There’s no accounting for taste: bait attractants and infrared digital cameras for detecting small to medium ground-dwelling mammals

Context Reliable information about the occurrence and distribution of threatened forest-dwelling mammals is critical for developing effective conservation plans. To optimise limited resources, advances need to be made to the toolkit available for detecting rare and cryptic fauna. Aims We trialled three bait attractants (peanut butter with oats, live mealworms and black truffle oil) in combination with infrared digital cameras to determine whether detection rates of forest-dwelling native mammals in south-eastern Australia were influenced by: (1) bait type; (2) previous visits by conspecifics; (3) previous visits by Rattus; and (4) duration of bait deployment. Methods Bait attractants were set at 40 camera stations in combination with odourless controls. Over two fortnight-long deployments, 1327 images were captured of 22 mammal and bird species. From these data, detailed statistical analyses were conducted of six mammal genera. Key results Peanut butter with oats was found to be a significantly better attractant than empty bait holders for Antechinus, Isoodon, Perameles and Rattus, but not for Potorous or Pseudocheirus. Truffle oil and mealworms were also significantly better attractants than the control for Rattus but not the other five genera. When Antechinus, Isoodon, Potorous or Rattus were detected at a bait station there was a significant likelihood they had been detected there during the previous 24 h. This was not the case for Perameles or Pseudocheirus. A prior visit by Rattus to a station had no significant influence on the detection probabilities of Antechinus, Isoodon, Perameles, Potorous and Pseudocheirus during the subsequent 24 h. Detection probabilities for Isoodon and Rattus declined significantly during the fortnight-long deployments but trends for the other genera were not significant. Conclusions Peanut butter with oats is an excellent general purpose bait for detecting small to medium-sized mammals. However, scope exists for using other baits to target species. For example, truffle oil baits may reduce by-catch of non-target Rattus in labour intensive cage trapping of bandicoots. Regardless of bait type, longer deployments are necessary to detect Perameles, Potorous or Pseudocheirus than Antechinus, Isoodon or Rattus. Implications Targeted detection of predominantly ground-dwelling mammals may be improved by better understanding the attraction of species to baits and required bait deployment times.

Diet of a native carnivore, the spotted-tailed quoll (Dasyurus maculatus), before and after an intense wildfire

The relationship between the diet of the spotted-tailed quoll (Dasyurus maculatus) and the abundance of its prey was investigated in rain-shadow woodland habitat in southern New South Wales for one year before and two years after a high-intensity, broad-scale wildfire. Scats were variously collected from quoll latrines and live-trapped animals during winter for each of the three years and analysed to determine prey items. Estimates of abundance of key ground-dwelling and arboreal medium-sized mammals were simultaneously obtained using plot-based survey techniques and spotlighting. Over the duration of the study, quoll diet was dominated by medium-sized mammals, particularly brushtail possums (Trichosurus spp.) and lagomorphs (rabbit and hare), followed by small and large-sized mammals. After the fire there was a shift in utilisation of food resources in response to significant changes in prey availability. Monitoring revealed that brushtail possums, lagomorphs and bandicoots were all significantly less abundant in the winter following the fire, and populations of lagomorphs, but not possums, then increased in the second winter after the fire. Quolls adapted to this by taking significantly more lagomorphs in each of the two years after the fire and by taking advantage of a short-term increase in the availability of carrion. The results of this study reaffirm that the spotted-tailed quoll is adaptable in its utilisation of available food, and that fires are not necessarily detrimental to the species and its prey base.

Detection of medium-sized ground-dwelling mammals using infrared digital cameras: an alternative way forward?

Infrared digital cameras were used to examine temporal detection rates of medium-sized ground-dwelling mammals in a coastal woodland landscape. From three successive deployments at fixed stations, a range of mammals was detected, including three target species: the long-nosed bandicoot, the long-nosed potoroo and the southern brown bandicoot. Reporting rates of target species were largely consistent and in some cases high. The swamp wallaby was the most commonly detected species, ranging from 47–67% of cameras on any given deployment. Long-nosed bandicoots were detected at 37–53% of cameras, long-nosed potoroos 13–23% and southern brown bandicoots 10–17%. In total, bandicoots and potoroos were detected at 23 of 30 sites (77%) while forage-diggings of these mammals were universally present. There were differences in the detection rate of bandicoots and potoroos in relation to 24-hourly cycles: all three species were less likely to be detected between dawn and dusk than dusk and dawn. Otherwise, with few exceptions, the rate at which bandicoots and potoroos were detected over time within a deployment did not vary markedly. Infrared digital cameras offer great potential as sampling devices for bandicoots and potoroos because of their greater detection efficiency relative to other techniques.

Differential gene flow of mitochondrial and nuclear DNA markers among chromosomal races of Australian morabine grasshoppers (Vandiemenella, viatica species group)

Recent theoretical developments have led to a renewed interest in the potential role of chromosomal rearrangements in speciation. Australian morabine grasshoppers (genus Vandiemenella, viatica species group) provide an excellent study system to test this potential role of chromosomal rearrangements because they show extensive chromosomal variation and formed the basis of a classic chromosomal speciation model. There are three chromosomal races, viatica19, viatica17, and P24(XY), on Kangaroo Island, South Australia, forming five parapatric populations with four putative contact zones among them. We investigate the extent to which chromosomal variation among these populations may be associated with barriers to gene flow. Population genetic and phylogeographical analyses using 15 variable allozyme loci and the elongation factor‐1α (EF‐1α) gene indicate that the three races represent genetically distinct taxa. In contrast, analyses of the mitochondrial cytochrome c oxidase subunit I (COI) gene show the presence of three distinctive and geographically localized groups that do not correspond with the distribution of the chromosomal races. These discordant population genetic patterns are likely to result from introgressive hybridization between the chromosomal races and range expansions/contractions. Overall, these results suggest that reduction of nuclear gene flow may be associated with chromosomal variation, or underlying genetic variation linked with chromosomal variation, whereas mitochondrial gene flow appears to be independent of this variation in these morabine grasshoppers. The identification of an intact contact zone between P24(XY) and viatica17 offers considerable potential for further investigation of molecular mechanisms that maintain distinct nuclear genomes among the chromosomal races.

Monitoring the Environmental Impact of Mining in Remote Locations through Remotely Sensed Data

Abstract Mining is an integral part of the development of many countries in the Asia‐Pacific region and is associated with adverse environmental and social impacts. The monitoring of mining in remote locations is problematic due to difficulties of access. Satellite remote sensing is able to provide information on landscape transformation in a cost‐effective way around large‐scale mines. The PT Freeport Indonesia mine in Papua (Indonesia) is the worlds largest copper‐gold mine and previous studies have documented a range of impacts. A multi‐temporal analysis of Landsat 5 imagery of the Freeport area was undertaken for the years between 1988 and 2004. Anthropogenic land cover changes were quantified by screen digitising polygons from three false colour composite images over this period to determine the area of forested land that had been cleared and the area that had been affected by mine‐derived sediment transported by the Ajkwa River system. The results show that both settlement and sediment had radically altered land cover and together had led to a sixfold increase in the area of ultra‐diverse lowland tropical rainforest cleared in the study area. The study highlights the utility of this method to monitor elements of the impact of large‐scale mining and other extensive forms of resource exploitation such as deforestation in developing countries.

Home range of the spotted-tailed quoll (Dasyurus maculatus), a marsupial carnivore, in a rainshadow woodland

The home ranges, movement patterns and spatial organisation of spotted-tailed quolls (Dasyurus maculatus maculatus) were studied in rainshadow woodland in southern New South Wales, Australia. Fourteen individuals were radio-collared and simultaneously tracked. Home-range size estimates ranged from 621 ha to at least 2561 ha for males, and 88 ha to at least 653 ha for females. Mean home-range size was significantly greater for males (992 ± 276 ha) than females (244 ± 72 ha). The maximum straight-line distances between successive fixes for males over 24-h and 48-h periods were 2529 and 4430 m, respectively, while for females these distances were 1865 and 3085 m. Mean maximum straight-line distances between successive fixes for males over a 24-h period were not significantly different from mean maximum straight-line distances of females (1493 ± 918 v. 1034 ± 540 m). However, over 48 h, the mean maximum distances between successive fixes for males was greater than that of females (2911 ± 934 v. 1680 ± 918 m). The home ranges of males mostly overlapped with those of other individuals, regardless of sex. In contrast, home ranges of females tended not to overlap with those of other females, suggesting some form of spatial separation. Home-range estimates derived for spotted-tailed quolls in our rainshadow woodland study site are comparable to those obtained for the species in wetter vegetation types. From a conservation perspective, it seems that habitat structure and the availability of prey is more important than rainfall or vegetation type in determining spatial requirements of the species. Until more advanced telemetry systems are developed, caution should be applied when using current home-range data on the species to infer breeding systems and patterns of spatial organisation, particularly the issue of territoriality among female quolls.

The effectiveness and cost of camera traps for surveying small reptiles and critical weight range mammals: a comparison with labour-intensive complementary methods

Abstract Context. Biodiversity studies often require wildlife researchers to survey multiple species across taxonomic classes. To detect terrestrial squamate and mammal species, often multiple labour-intensive survey techniques are required. Camera traps appear to be more effective and cost-efficient than labour-intensive methods for detecting some mammal species. Recent developments have seen camera traps used for detecting terrestrial squamates. However, the performance of camera traps to survey terrestrial squamate and mammal species simultaneously has not been evaluated. Aim. We compared the effectiveness and financial cost of a camera trapping method capable of detecting small squamates and mammals with a set of labour-intensive complementary methods, which have been used in a long-term monitoring program. Methods. We compared two survey protocols: one employed labour-intensive complementary methods consisting of cage traps, Elliott traps and artificial refuges; the second utilised camera traps. Comparisons were made of the total number of species detected, species detectability, and cost of executing each type of survey. Key results. Camera traps detected significantly more target species per transect than the complementary methods used. Although camera traps detected more species of reptile per transect, the difference was not significant. For the initial survey, camera traps were more expensive than the complementary methods employed, but for realistic cost scenarios camera traps were less expensive in the long term. Conclusions. Camera traps are more effective and less expensive than the complementary methods used for acquiring incidence data on terrestrial squamate and mammal species. Implications. The camera trapping method presented does not require customised equipment; thus, wildlife managers can use existing camera trapping equipment to detect cryptic mammal and squamate species simultaneously.

Effective detection methods for medium-sized ground-dwelling mammals: a comparison between infrared digital cameras and hair tunnels

Abstract Context. Conservation planning for threatened species depends on improved knowledge of the whereabouts of critical populations and thus the development of optimal detection methods. Aims. To compare the effectiveness of infrared cameras and hair tunnels for detecting small to medium-sized ground-dwelling mammals in south-eastern Australian forests. Methods. Reconyx PC90 cameras were paired with Handiglaze hair tunnels at 110 stations in south-eastern New South Wales. All devices were baited using rolled oats, peanut butter and pistachio essence and left in situ for a minimum duration of 30 days. Camera detection data were analysed for the first 15 and 30 days, whereas hair-tunnel detection data were analysed for the entire duration of deployment. Linear mixed models with site as a random effect and device as a fixed effect were developed for mammal species richness. Linear mixed logistic regression models for binary data were developed for detection probabilities of five taxa of interest, namely, Isoodon, Perameles, Potorous, Trichosurus and Wallabia. Key results. Hair tunnels detected eight mammal species, whereas cameras detected 18 species. Modelled detection rates using cameras were 3.16 ± 0.21 species per site after 15 days and 4.24 ± 0.23 species per site after 30 days, whereas hair tunnels detected 0.34 ± 0.21 species over the entire deployment. Cameras were therefore approximately 9–12 times better at measuring mammal richness than were hair tunnels, depending on survey duration. In all calculations, the probability of detecting the five taxa of interest was significantly greater using cameras than using hair tunnels. Conclusions. Infrared cameras and hair tunnels offer ethical advantages over direct detection methods such as cage trapping for small to medium-sized ground-dwelling mammals. Cameras also offer practical benefits because they work for protracted periods, without frequent checking by field researchers. Cameras are more effective at detecting a wide range of species than are hair tunnels and are significantly better for detecting the taxa we examined. Unlike hair tunnels, cameras sometimes allow for the identification of individual animals, and provide information about frequency of habitat use, reproductive status and aspects of behaviour. Implications. On a unit by unit basis, infrared cameras are a far more efficient way to census a broad spectrum of ground-dwelling mammals than are hair tunnels.

Distribution of the southern brown bandicoot (Isoodon obesulus) in the Portland region of south-western Victoria

The southern brown bandicoot (Isoodon obesulus) occurs across the periphery of southern and eastern Australia as a series of isolated regional populations. Historical records and recent surveys conducted for I. obesulus indicate that it has disappeared or decreased significantly from many parts of its former range. Vegetation clearance, habitat fragmentation, feral predators and fire have all been implicated in the decline of the species. This paper examines the distribution of I. obesulus in the Portland region of south-western Victoria. Historical records of I. obesulus were compiled from the specimen collection of Museum Victoria, the Atlas of Victorian Wildlife, Portland Field Naturalists’ Club records and anecdotal sources. Field surveys were conducted to determine the current distribution of I. obesulus in the study area based on evidence of its foraging activity. The historical records reveal limited information: most are clustered around centres of human activity, indicating observational bias. The field surveys demonstrate that I. obesulus occurs in the Portland region as a series of local populations. Each local population is associated with a patch of remnant native vegetation separated from neighbouring patches by dispersal barriers. Within these habitat remnants the occurrence of the species is sporadic. Approximately 69% of the potential habitat is managed by the Forests Service, 31% is managed by Parks Victoria, and less than 0.5% is held under other tenures. Spatial isolation of habitat remnants, fires and feral predators are the main threats to I. obesulus in the Portland region.