Carnivorous Marsupial Research Articles

Cranium of Sipalocyon externus (Metatheria, Sparassodonta) with remarks on the paleoneurology of hathliacynids and insights into the Early Miocene sparassodonts of Patagonia, Argentina

In this contribution, we investigate two sparassodonts from the Sarmiento Formation (Colhuehuapian Age; Early Miocene) recovered at the Patagonian locality of Sacanana, Chubut Province, Argentina. The first specimen (MACN-Pv CH1911), identified as Sipalocyon externus, is an almost complete cranium with upper dentition. The second specimen (MACN-Pv CH40), referred to Borhyaena macrodonta, consists of a fragmentary rostral portion of the face with associated m3–m4. The cranium of S. externus was studied through µCT-scanning to investigate its internal anatomy and infer paleoecological aspects of olfaction and hearing. In general, the endocranial anatomy and encephalization quotient are like those of other metatherians. We report the presence of an accessory transverse diploic sinus that has not previously been described in marsupials. Elements of the nasal cavity (e.g., turbinals, ossified nasal septum, cribriform plate) of S. externus exhibit features that are widespread among marsupials. Sense of olfaction, as evaluated from the cribriform plate and the 3D models of the olfactory bulbs, appears to have grossly resembled that of the domestic cat, a well-researched therian proxy. The dimensions of the tympanic membrane, as estimated from the preserved ectotympanic, suggest that the optimal hearing frequency of S. externus would have been similar to that of extant carnivorous marsupials. In sum, our study suggests that S. externus was a typical small-bodied (2–3 kg) hypercarnivorous metatherian that primarily relied on vision to hunt its prey, complemented by other sensory capabilities (olfaction and hearing), in a similar manner to small felids.

Spontaneous Lesions of Endangered Geriatric Julia Creek Dunnarts (Sminthopsis douglasi, Archer 1979) with Emphasis in Reproductive Pathology.

Julia Creek dunnarts are an endangered species of carnivorous marsupials and the focus of multiple conservation strategies involving significant resources such as captive breeding programs. Despite the relevance for conservation, no study to date has focused on evaluating geriatric diseases in dunnarts. This study describes the pathology findings in a group of one wild and thirty-five captive-born, mostly geriatric Julia Creek dunnarts that failed to produce offspring over multiple breeding periods. A total of 20 females and 16 males were submitted for a postmortem examination, with ages ranging from 9 to 42 and 12 to 42 months for females and males, respectively. Of these, 10 had unremarkable findings. The most common condition in females was cystic glandular hyperplasia (n = 8), typical of hormonal dysregulation profiles in senescence, particularly hyperestrogenism. Rarely, cutaneous disease represented by unidentified dermal round cell infiltrates was observed in females (n = 2). Primary reproductive hormonal dysregulation was also suspected in males diagnosed with testicular degeneration, aspermatogenesis and/or atrophy (n = 3). Cutaneous round cell infiltrates, possibly compatible with epitheliotropic lymphomas, were seen in males (n = 3), and 2/3 affected males also had concurrent testicular degeneration or atrophy, indicating male sex could be a predictor for lymphoid neoplasia in aged dunnarts, especially in individuals with concurrent testosterone-luteinizing hormone dysregulation as it occurs in gonadectomized animals. The role of an underlying viral etiology is also explored. This study is the first to describe major spontaneous diseases in endangered aged Julia Creek dunnarts, providing an important understanding of senescence and geriatric diseases within a conservation context.

Ethyl-Iophenoxic acid as a serum marker for oral baiting of Tasmanian devils

Oral baits containing vaccines, medicants or toxicants have been delivered to a broad range of wildlife species to protect against or treat disease, or suppress populations. Ethyl-Iophenoxic acid (Et-IPA) is used as a biomarker to determine oral bait consumption by wildlife species to assess and refine baiting strategies. Et-IPA is a persistent biomarker in many eutherian mammal species but not in the two marsupial species, swamp wallaby (Wallabia bicolor) and brushtail possum (Trichosurus vulpecula), tested to date. Et-IPA has not previously been evaluated in carnivorous marsupials. The Tasmanian devil (Sarcophilus harrisii), the largest extant carnivorous marsupial, is threatened by devil facial tumour disease (DFTD). Development of an oral DFTD vaccine bait is underway. In this study, eight devils were fed between 1 mg and 50 mg Et-IPA via oral baits to assess the effectiveness of Et-IPA as a serum biomarker for this species. Using liquid chromatography with tandem mass spectrometry, serum Et-IPA was detected in the devils up to 206 days after ingestion. This study demonstrates the utility of Et-IPA for estimating oral bait consumption by devils, the first carnivorous marsupial species to which this applies.

Comparative three-dimensional jaw muscle anatomy of marsupial carnivores (Dasyurus spp.) and the termite-eating numbat (Myrmecobius fasciatus).

Among marsupials, the endangered numbat (Myrmecobius fasciatus) is the only obligate myrmecophage with a diet comprised strictly of termites. Like many other specialised myrmecophagous mammals, numbats have a gracile and highly specialised skull morphology with an elongated rostrum and small braincase. Myrmecobiidae is one of four taxonomic families within the Australasian marsupial order Dasyuromorphia, and to date, the muscular anatomy of any member of this group is relatively poorly known. We utilised microdissection and contrast-enhanced microcomputed tomography scanning to provide the first comprehensive qualitative and quantitative descriptions of jaw muscle anatomy in numbats and quolls (Dasuyrus species). The arrangement of the jaw muscles across these species was conservative, both in gross anatomy and muscle proportions, corresponding to a 'generalised' mammalian pattern. In contrast to Dasyurus, the jaw muscles of the numbat were greatly reduced. Many aspects of the muscle anatomy of the numbat were similar to patterns reported in other myrmecophagous species, particularly a greatly reduced temporalis muscle. Unusually, the digastric muscle in the numbat was comprised of a single, large anterior belly while the posterior belly was absent. We propose that the enlarged anterior belly of the digastric may be linked to jaw stabilisation and coordination of tongue movements during feeding. The lateral insertion and fascial connection of the digastric to the tongue in numbats may also aid in distributing stress evenly across the jaw and minimise muscle fatigue. The muscle descriptions and three-dimensional models provided in this study will facilitate further analysis of musculoskeletal adaptation and evolution within the Dasyuromorphia.

Movements and habitat selection of a marsupial carnivore in a modified landscape

AbstractLandscape modification is a major threat to carnivores worldwide, but modified landscapes can also provide important habitat for these species, as protected areas alone are insufficient. Understanding how carnivores use modified landscapes, such as production forests, can inform management strategies to improve the value of these landscapes to carnivores. Little is known about habitat selection by marsupial carnivores in production forests, where they occupy a similar ecological niche to their more well‐studied eutherian counterparts. We used GPS tracking, Hidden Markov Models, and Manly's selection ratios to identify the habitat selected in three behavioral states by the largest marsupial carnivore, the Tasmanian devil (Sarcophilus harrisii), in a timber plantation‐dominated landscape. Behavioral states were approximated as: state 1, resting or feeding at a carcass; state 2, foraging; and state 3, travel. Devils did not show preferences for any of native forest, native grassland, and plantation in any behavioral state. Within plantations, devils preferred a plantation age of 4–7 years (selection ratio [wi] = 1.52). Devils preferred roads (state 1: wi = 2.71, state 2: wi = 2.48, state 3: wi = 2.97) and plantation edges (state 1: wi = 2.38, state 2: wi = 2.24, state 3: wi = 2.78) in all behavioral states, and moved faster on roads and edges than away from them. Together, our results indicate devils use road and edges for foraging (scavenging and hunting) and travel. No measured habitat variables influenced devil home range size. To support devils in plantation landscapes, we recommend maintaining a heterogeneous landscape of different plantation ages and native remnants and reducing the risk of vehicle collisions by minimizing forestry traffic at night. Tasmanian devils share similar adaptable traits to generalist eutherian carnivore species in their use of modified landscapes. Plantations can provide valuable habitat for this and other threatened predator species.

Over-eruption in marsupial carnivore teeth: compensation for a constraint

Pronounced over-eruption of the canine teeth, causing the cervical enamel margin to extend beyond the alveolar bone and exposing the root, occurs with age and growth in Australian marsupial carnivores, much more than in eco-morphologically equivalent placental carnivores. Suppression of functional tooth replacement is characteristic of marsupials, where most placentals have the primitive diphyodont pattern of two generations of incisor, canine and premolar teeth. Canine and molar tooth dimensions of four species of marsupial carnivores (thylacine Thylacinus cynocephalus , Tasmanian devil Sarcophilus harrisii and two quolls Dasyurus spp . ) and canine dimensions of seven eco-morphologically equivalent placental carnivore species were measured from museum specimens. Canine dimensions were measured in a time series on live wild-living individual devils and quolls. The canine teeth and to a lesser extent the molar teeth of marsupial carnivores continue to erupt through life, resulting in a net increase in tooth height and diameter, a phenomenon not evident in placental carnivores. Potential mechanisms causing over-eruption include tooth wear and gradual release of occlusal pressure as the individual grows. Over-eruption in marsupial carnivores may be a compensatory response for tooth size limits imposed by monophyodont tooth replacement, ensuring that animal's teeth are scaled to jaw size from juvenile to adulthood.

Divergent hepaciviruses, delta-like viruses, anda chu-like virus inAustralian marsupial carnivores (dasyurids).

Although Australian marsupials are characterised by unique biology and geographic isolation, little is known about the viruses present in these iconic wildlife species. The Dasyuromorphia are an order of marsupial carnivores found only in Australia that include both the extinct Tasmanian tiger (thylacine) and the highly threatened Tasmanian devil. Several other members of the order are similarly under threat of extinction due to habitat loss, hunting, disease, and competition and predation by introduced species such as feral cats. We utilised publicly available RNA-seq data from the National Center for Biotechnology Information (NCBI) Sequence Read Archive (SRA) database to document the viral diversity within four Dasyuromorph species. Accordingly, we identified fifteen novel virus sequences from five DNA virus families (Adenoviridae, Anelloviridae, Gammaherpesvirinae, Papillomaviridae, and Polyomaviridae) and three RNA virus taxa: the order Jingchuvirales, the genus Hepacivirus, and the delta-like virus group. Of particular note was the identification of a marsupial-specific clade of delta-like viruses that may indicate an association of deltaviruses with marsupial species. In addition, we identified a highly divergent hepacivirus in a numbat liver transcriptome that falls outside of the larger mammalian clade. We also detect what may be the first Jingchuvirales virus in a mammalian host-a chu-like virus in Tasmanian devils-thereby expanding the host range beyond invertebrates and ectothermic vertebrates. As many of these Dasyuromorphia species are currently being used in translocation efforts to reseed populations across Australia, understanding their virome is of key importance to prevent the spread of viruses to naive populations.

How collections and reputation were built out of Tasmanian violence: thylacines (Thylacinus cynocephalus) and Aboriginal remains from Morton Allport (1830–1878)

Through European colonization, First Nations peoples were subjected to systematic and violent actions to dispossess them of their land and sovereignty. In Tasmania, this involved government-sponsored bounties as well as militaristic and diplomatic efforts to remove Indigenous peoples from the landscape. At the same time, and using similar rhetoric, thylacines ( Thylacinus cynocephalus (Harris, 1808)) suffered similarly from settler colonists. Thylacines (also known as Tasmanian tigers or Tasmanian wolves) were the largest marsupial carnivores of modern times, but became extinct in the twentieth century. There are several parallels between the treatment and representation of thylacines and Indigenous Tasmanian people, and how their remains were traded. This allows for analysis of how the environmental and human costs of the colonial project were enmeshed with practices of natural history. A central figure in the export of both thylacines and Indigenous remains from Tasmania was Morton Allport (1830–1878). This paper shows that Allport actively built his scientific reputation by exchanging specimens for honours. It asks whether this was a widespread model for other colonial figures who may have used specimen-based philanthropy to develop a form of soft power through associations with respected institutions such as learned societies, universities and museums. Figures like Allport played the role of a type of colonial settler-intermediary, valued for providing privileged access to specimens to the metropole. Allport also worked to augment scientific work in Tasmania and the economic reputation of the colony, demonstrating that the development of social networks and scientific reputations of colonial figures were entwined with the status and success of the colonies themselves.

Clade-specific forebrain cytoarchitectures of the extinct Tasmanian tiger

The thylacine, or Tasmanian tiger, is the largest of modern-day carnivorous marsupials and was hunted to extinction by European settlers in Australia. Its physical resemblance to eutherian wolves is a striking example of evolutionary convergence to similar ecological niches. However, whether the neuroanatomical organization of the thylacine brain resembles that of canids and how it compares with other mammals remain unknown due to the scarcity of available samples. Here, we gained access to a century-old hematoxylin-stained histological series of a thylacine brain, digitalized it at high resolution, and compared its forebrain cellular architecture with 34 extant species of monotremes, marsupials, and eutherians. Phylogenetically informed comparisons of cortical folding, regional volumes, and cell sizes and densities across cortical areas and layers provide evidence against brain convergences with canids, instead demonstrating features typical of marsupials, and more specifically Dasyuridae, along with traits that scale similarly with brain size across mammals. Enlarged olfactory, limbic, and neocortical areas suggest a small-prey predator and/or scavenging lifestyle, similar to extant quolls and Tasmanian devils. These findings are consistent with a nonuniformity of trait convergences, with brain traits clustering more with phylogeny and head/body traits with lifestyle. By making this resource publicly available as rapid web-accessible, hierarchically organized, multiresolution images for perpetuity, we anticipate that additional comparative insights might arise from detailed studies of the thylacine brain and encourage researchers and curators to share, annotate, and preserve understudied material of outstanding biological relevance.

Performance of Felixer devices when faced with captive‐held Spotted‐tailed Quolls: Do they pose a risk to an endangered marsupial carnivore?

SummaryFeral Cats are widespread and common across Australia, preying upon a wide diversity and large quantity of vertebrates and invertebrates. Curbing their impacts demands developing new control methods, as existing techniques are only usually partially successful. One such new method is the Felixer, a device that uses a combination of sensors to differentiate Feral Cats from other fauna before delivering a toxic gel to the fur of its target. Subsequently, this gel is then groomed and ingested. Before the Felixer can be more widely adopted, however, it is important to understand its target specificity. In a series of pen trials, we examined the ability of Felixer devices to discriminate Spotted‐tailed Quolls, a cat‐sized marsupial carnivore high on the list of species of concern. Over several weeks, multiple Spotted‐tailed Quolls were each individually placed in pens with Felixers programmed in photograph only mode to take photographs only when sensors were triggered. Overall, there were almost 4000 detection events where Quolls passed in front of these devices and photographs taken. Nearly 1300 of these detections showed Quolls in a perpendicular or side‐on position, ideally placed for the Felixer sensor arrays. Despite this exposure, there were no instances where the Felixer devices indicated that they would have activated on Quolls, had they been in lethal mode. This finding adds to recently published work in Tasmania, that also showed Quolls were highly unlikely to be incorrectly identified. Nevertheless, further studies of non‐target discrimination by the Felixer device on other species of native wildlife is vital before they are made fully operational. This is particularly the case on the eastern seaboard of the country where the device has not yet been widely used and much remains to be learned about how they perform when faced with different species.

What drives the abundance of marsupial carnivores in production forest landscapes?

Production forest landscapes provide important habitat for wildlife but expose them to disturbances from forestry practices. Understanding how threatened carnivores use production forests can inform management practices to improve their conservation. While there have been many studies of eutherian carnivores in production forests, the use of these landscapes by marsupial carnivores is poorly understood. Using a network of remote cameras, we investigated the use of forestry landscape features by two endangered marsupial carnivores, Tasmanian devils (Sarcophilus harrisii) and eastern quolls (Dasyurus viverrinus). Devil and quoll abundance increased with the extent of timber plantations within production forest landscapes. Overall, devils were positively associated with higher tree density and eastern quolls with indicators of open habitat such as less understorey, fewer trees and more grassland. Within plantations, devil abundance increased with the volume of windrows (piles of woody debris from harvesting arranged in rows), as did eastern quoll abundance in pine plantations. Eastern quoll abundance was higher in pine plantations established on pasture than those established on cleared native forest land, and in eucalypt plantations, higher with windrows comprised of plantation debris. Neither species showed a strong response to logging-related features in native forest such as time since harvest, though eastern quolls were positively associated with log cover. Our results demonstrate that plantations provide valuable habitat for marsupial carnivores and that they can persist in harvested native forests. Windrows likely benefit devils and eastern quolls by providing denning, shelter and foraging opportunities, and should be managed as important habitat features for carnivores. These findings can be used by forest managers to guide decisions and help maintain threatened carnivore populations in human-modified landscapes.

Population genomics of a predatory mammal reveals patterns of decline and impacts of exposure to toxic toads.

Mammal declines across northern Australia are one of the major biodiversity loss events occurring globally. There has been no regional assessment of the implications of these species declines for genomic diversity. To address this, we conducted a species-wide assessment of genomic diversity in the northern quoll (Dasyurus hallucatus), an Endangered marsupial carnivore. We used next generation sequencing methods to genotype 10,191 single nucleotide polymorphisms (SNPs) in 352 individuals from across a 3220-km length of the continent, investigating patterns of population genomic structure and diversity, and identifying loci showing signals of putative selection. We found strong heterogeneity in the distribution of genomic diversity across the continent, characterized by (i) biogeographical barriers driving hierarchical population structure through long-term isolation, and (ii) severe reductions in diversity resulting from population declines, exacerbated by the spread of introduced toxic cane toads (Rhinella marina). These results warn of a large ongoing loss of genomic diversity and associated adaptive capacity as mammals decline across northern Australia. Encouragingly, populations of the northern quoll established on toad-free islands by translocations appear to have maintained most of the initial genomic diversity after 16 years. By mapping patterns of genomic diversity within and among populations, and investigating these patterns in the context of population declines, we can provide conservation managers with data critical to informed decision-making. This includes the identification of populations that are candidates for genetic management, the importance of remnant island and insurance/translocated populations for the conservation of genetic diversity, and the characterization of putative evolutionarily significant units.

A Chromosome-Scale Hybrid Genome Assembly of the Extinct Tasmanian Tiger (Thylacinus cynocephalus).

The extinct Tasmanian tiger or thylacine (Thylacinus cynocephalus) was a large marsupial carnivore native to Australia. Once ranging across parts of the mainland, the species remained only on the island of Tasmania by the time of European colonization. It was driven to extinction in the early 20th century and is an emblem of native species loss in Australia. The thylacine was a striking example of convergent evolution with placental canids, with which it shared a similar skull morphology. Consequently, it has been the subject of extensive study. While the original thylacine assemblies published in 2018 enabled the first exploration of the species’ genome biology, further progress is hindered by the lack of high-quality genomic resources. Here, we present a new chromosome-scale hybrid genome assembly for the thylacine, which compares favorably with many recent de novo marsupial genomes. In addition, we provide homology-based gene annotations, characterize the repeat content of the thylacine genome, and show that consistent with demographic decline, the species possessed a low rate of heterozygosity even compared to extant, threatened marsupials.

The importance of species-specific survey designs: prey camera trap surveys significantly underestimate the detectability of endangered spotted-tailed quolls

The spotted-tailed quoll (Dasyurus maculatus) is an endangered marsupial carnivore that is often surveyed using camera traps. Camera trap surveys targeting quolls typically use meat-based lures and specific camera setups tailored to increase the probability of quoll detection. However, where quolls occur, they can also be incidentally detected as non-target species in camera surveys targeting small to medium-sized herbivorous or omnivorous mammals (‘prey’ surveys). We investigated whether quoll detectability using traditional ‘prey’ camera surveys could sufficiently approximate quoll detectability using targeted ‘quoll’ surveys, potentially enabling quoll data from prey surveys to be used in lieu of undertaking additional quoll-specific surveys. We used 50 Reconyx HC600 cameras to quantify and compare quoll detectability between prey and quoll surveys at each of two different sites. The number of quoll detections, number of individual quolls detected and the probability of quoll detection at both sites were significantly higher in quoll surveys than in prey surveys. Our findings suggest that prey surveys substantially underestimate quoll detectability, resulting in incomplete datasets. We therefore caution against using quoll detection data from prey camera trap surveys for anything other than incidental presence observations, to avoid misleading survey and management outcomes.

Community structure of dasyurid marsupials in the arid Pilbara is consistent with a top-down system, their distribution and abundance depend on that of larger members of the guild

The semi-arid Pilbara region of Western Australia has an exceptionally large number of sympatric carnivorous marsupials (dasyurids). The multi-scale patchwork of sandplain grassland, riparian and rock outcrop habitats overlain with fine-scale variation in fire age may provide opportunities for exceptional niche differentiation. The goal of this study was to determine how dasyurids in the Pilbara partition these habitats in space and time. We focused on four species detectable on camera traps: northern quolls (largest), mulgaras, kalutas, and stripe-faced dunnarts (smallest). We found fine-scale partitioning in spatial and temporal patterns among sympatric species, and unusually, fire age specialisation in the smallest species, dunnarts, which were associated with recently burnt areas that had low prey availability. Kalutas were active throughout the 24-h period, with seasonal differences that support the hypothesis of energy preservation. Opposing habitat associations of kalutas and dunnarts are consistent with top-down pressures. We suggest that, in habitats where quolls and mulgaras are absent, kalutas may have experienced mesopredator release.

The influence of divergent reproductive strategies in shaping modularity and morphological evolution in mammalian jaws.

Marsupial neonates are born at an earlier developmental stage than placental mammals, but the rapid development of their forelimbs and cranial skeleton allows them to climb to the pouch, begin suckling and complete their development ex utero. The mechanical environment in which marsupial neonates develop is vastly different from that of placental neonates, which exhibit a more protracted development of oral muscles and bones. This difference in reproductive strategy has been theorized to constrain morphological evolution in the oral region of marsupials. Here, we use 3D morphometrics to characterize one of these oral bones, the lower jaw (dentary), and assess modularity (pattern of covariation among traits), morphological disparity and rates of morphological evolution in two clades of carnivorous mammals: the marsupial Dasyuromorphia and placental fissiped Carnivora. We find that dasyuromorph dentaries have fewer modules than carnivorans and exhibit tight covariation between the angular and coronoid processes, the primary attachment sites for jaw-closing muscles. This pattern of modularity may result from the uniform action of muscles on the developing mandible during suckling. Carnivorans are free from this constraint and exhibit a pattern of modularity that more strongly reflects genetic and developmental signals of trait covariation. Alongside differences in modularity, carnivorans exhibit greater disparity and faster rates of morphological evolution compared with dasyuromorphs. Taken together, this suggests dasyuromorphs have retained a signal of trait covariation that reflects the outsized influence of muscular force during early development, a feature that may have impacted the ability of marsupial carnivores to explore specialized regions of morphospace.

Species identification of Australian marsupials using collagen fingerprinting

The study of faunal remains from archaeological sites is often complicated by the presence of large numbers of highly fragmented, morphologically unidentifiable bones. In Australia, this is the combined result of harsh preservation conditions and frequent scavenging by marsupial carnivores. The collagen fingerprinting method known as zooarchaeology by mass spectrometry (ZooMS) offers a means to address these challenges and improve identification rates of fragmented bones. Here, we present novel ZooMS peptide markers for 24 extant marsupial and monotreme species that allow for genus-level distinctions between these species. We demonstrate the utility of these new peptide markers by using them to taxonomically identify bone fragments from a nineteenth-century colonial-era pearlshell fishery at Bandicoot Bay, Barrow Island. The suite of peptide biomarkers presented in this study, which focus on a range of ecologically and culturally important species, have the potential to significantly amplify the zooarchaeological and paleontological record of Australia.

A chromosome-level genome of Antechinus flavipes provides a reference for an Australian marsupial genus with male death after mating.

The 15 species of small carnivorous marsupials that comprise the genus Antechinus exhibit semelparity, a rare life‐history strategy in mammals where synchronized death occurs after one breeding season. Antechinus males, but not females, age rapidly (demonstrate organismal senescence) during the breeding season and show promise as new animal models of ageing. Some antechinus species are also threatened or endangered. Here, we report a chromosome‐level genome of a male yellow‐footed antechinus Antechinus flavipes. The genome assembly has a total length of 3.2 Gb with a contig N50 of 51.8 Mb and a scaffold N50 of 636.7 Mb. We anchored and oriented 99.7% of the assembly on seven pseudochromosomes and found that repetitive DNA sequences occupy 51.8% of the genome. Draft genome assemblies of three related species in the subfamily Phascogalinae, two additional antechinus species (Antechinus argentus and A. arktos) and the iteroparous sister species Murexia melanurus, were also generated. Preliminary demographic analysis supports the hypothesis that climate change during the Pleistocene isolated species in Phascogalinae and shaped their population size. A transcriptomic profile across the A. flavipes breeding season allowed us to identify genes associated with aspects of the male die‐off. The chromosome‐level A. flavipes genome provides a steppingstone to understanding an enigmatic life‐history strategy and a resource to assist the conservation of antechinuses.

Spatial and temporal interactions between endangered spotted‐tailed quolls and introduced red foxes in a fragmented landscape

AbstractHabitat fragmentation can have detrimental impacts on native predators globally through the loss of habitat and associated impacts from introduced predators.The endangered spotted‐tailed quoll (Dasyurus maculatus) is the largest marsupial carnivore on mainland Australia and is sympatric with an introduced predator, the red fox (Vulpes vulpes). Spotted‐tailed quolls are considered a forest‐dependent species and are often associated with large, intact forested habitats where abundance of prey is high and competition with foxes is low. Spotted‐tailed quolls are known to persist in some fragmented habitats in sympatry with foxes; however, the mechanisms facilitating this coexistence are unclear. For 15 months in 2018–19, we used camera traps to investigate whether coexistence between quolls and foxes in a fragmented landscape was facilitated by spatial and/or temporal separation of activity. We found no evidence of spatial separation, with quolls detected on the majority of cameras where foxes were detected. There was considerable temporal overlap between quolls and foxes (Δ1 = 0.71–0.81) and no evidence that fox presence influenced the temporal activity of quolls (Δ1 = 0.76–0.80). Furthermore, there was no evidence of within‐night spatiotemporal avoidance between quolls and foxes (R2 < 0.01). Our findings suggest that quolls do not offset their spatial and temporal activity to avoid foxes in this fragmented landscape. The spatial and temporal sympatry between quolls and foxes is possibly facilitated by low fox density at this site, suggested by low fox detections. The lack of separation between quoll and fox activity could also explain why quolls become locally extinct in other fragmented landscapes because quolls may not modify their activity to avoid foxes. Future research should focus on investigating quoll and fox interactions along a gradient of fox densities and assess if higher fox densities influence spatial and temporal coexistence with quolls in fragmented landscapes.

The immunopeptidomes of two transmissible cancers and their host have a common, dominant peptide motif.

SummaryTransmissible cancers are malignant cells that can spread between individuals of a population, akin to both a parasite and a mobile graft. The survival of the Tasmanian devil, the largest remaining marsupial carnivore, is threatened by the remarkable emergence of two independent lineages of transmissible cancer, devil facial tumour (DFT) 1 and devil facial tumour 2 (DFT2). To aid the development of a vaccine and to interrogate how histocompatibility barriers can be overcome, we analysed the peptides bound to major histocompatibility complex class I (MHC‐I) molecules from Tasmanian devil cells and representative cell lines of each transmissible cancer. Here, we show that DFT1 + IFN‐γ and DFT2 cell lines express a restricted repertoire of MHC‐I allotypes compared with fibroblast cells, potentially reducing the breadth of peptide presentation. Comparison of the peptidomes from DFT1 + IFNγ, DFT2 and host fibroblast cells demonstrates a dominant motif, despite differences in MHC‐I allotypes between the cell lines, with preference for a hydrophobic leucine residue at position 3 and position Ω of peptides. DFT1 and DFT2 both present peptides derived from neural proteins, which reflects a shared cellular origin that could be exploited for vaccine design. These results suggest that polymorphisms in MHC‐I molecules between tumours and host can be ‘hidden’ by a common peptide motif, providing the potential for permissive passage of infectious cells and demonstrating complexity in mammalian histocompatibility barriers.