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Context: Fire regimes are changing with ongoing climate change, which is leading to an increase in fire frequency and severity. Australia's Black Summer wildfires burned >12 million hectares in 2019–2020, affecting numerous threatened animal species. One of the species predicted to be most impacted was the threatened southern greater glider, an arboreal, hollow-dependent folivore, endemic to eastern Australia's eucalypt forests. Aims: This study aimed to assess how the 2019–2020 wildfires affected greater glider abundance and the resources they depend on in Woomargama National Park, New South Wales, Australia. Methods: We categorised 32 sites into four fire severity treatments with eight sites for each treatment: unburned (continuous unburned vegetation); refuges (unburned patches within the fire's perimeter); low-moderate severity; and high severity. We carried out two spotlight surveys per site using the double-observer method, beginning 21 months after the fires. We also conducted vegetation assessments on the same transects. To analyse the data, we used Generalised Linear Models to compare habitat differences based on fire severity, and N-mixture models to model greater glider detectability and abundance in relation to habitat and fire severity. Key results: We found that fire severity depleted several habitat variables including canopy cover and the number of potentially hollow-bearing trees, a resource that greater gliders rely on. Greater glider abundance also decreased in all burn categories, with the greatest decline experienced in areas burned at high severity. We also found that greater glider abundance was much lower in fire refuges than unburned habitat outside of the fire zone. Conclusions: Greater glider declines following severe wildfire can be at least partly attributed to the level of vegetation loss and the associated loss of key habitat resources. The contribution of direct mortality to population declines remains unknown. Implications: Greater glider conservation will rely heavily on protecting expansive unburned areas of suitable habitat and maintaining hollow-bearing trees. This study aimed to assess the impact of the 2019–2020 wildfires on the abundance of the southern greater glider in Woomargama National Park, New South Wales, Australia. Our results indicated that southern greater glider populations were lower in areas that burned during the fires, as well as in small, unburned refuges. These declines were linked to the loss of critical resources, such as an intact canopy and hollow-bearing trees. Photograph by Mikayla Green. [ABSTRACT FROM AUTHOR]

Context: Freshwater ecosystems rank among the most threatened environments on Earth. Monitoring aquatic and semi-aquatic species is vital to informing conservation of freshwater ecosystems. However, many semi-aquatic mammals can be difficult to detect with conventional survey methods. Aims: We aimed to identify the most effective survey method for detecting an Australian semi-aquatic mammal, the rakali (Hydromys chrysogaster). Methods: We compared rakali detection rates among camera-trapping, live-trapping and visual surveys, and tested the influence of camera angle, trap proximity to water and time of survey, across the Yanco Creek system in southern New South Wales. Key results: Nocturnal spotlight surveys were the most effective method for detecting rakali, with most observations occurring while individuals were foraging or swimming in the water. Camera traps facing a floating platform and cage traps mounted on floating platforms performed better than those deployed on land. Downward-facing camera traps detected rakali three times more often than did forward-facing cameras. Trapping rakali was unreliable, with the species detected at fewer than half of the sites where presence was confirmed via visual observation and camera traps. For species absence to be determined with 95% confidence, 2–4 weeks of nightly trapping is required, compared with six nights of visual surveys or 12 nights for a platform-facing camera. Morning visual surveys were largely ineffective because of predominantly nocturnal rakali activity and difficulty in detecting signs in creek environments. Conclusions: The likelihood of detecting rakali can be maximised through the use of nightly spotlighting and deployment of baited camera traps focussed on platforms or natural resting areas within a water body. Implications: Understanding the effectiveness of each method is essential for developing species-appropriate protocols for population monitoring. Our findings present suitable options to be further explored among the 100-plus small (<1 kg) semi-aquatic mammals worldwide that share similar behaviours and characteristics to the rakali, many of which are threatened or data deficient. Cryptic semi-aquatic mammals present a particular challenge to monitor because of their unique lifestyles. We aimed to identify the most effective methods to detect the seldom-studied rakali, a native Australian semi-aquatic mammal; spotlighting and camera traps placed over water provided the greatest detection probabilities. We present a novel method to monitor rakali, which has the potential to improve the detection and conservation of other small semi-aquatic mammals. Photograph by Emmalie Sanders. [ABSTRACT FROM AUTHOR]

Single-cell RNA sequencing of embryos can resolve the transcriptional landscape of development at unprecedented resolution. To date, single-cell RNA-sequencing studies of mammalian embryos have focused exclusively on eutherian species. Analysis of mammalian outgroups has the potential to identify deeply conserved lineage specification and pluripotency factors, and can extend our understanding of X dosage compensation. Metatherian (marsupial) mammals diverged from eutherians around 160 million years ago. They exhibit distinctive developmental features, including late implantation.sup.1 and imprinted X chromosome inactivation.sup.2, which is associated with expression of the XIST-like noncoding RNA RSX.sup.3. Here we perform a single-cell RNA-sequencing analysis of embryogenesis and X chromosome inactivation in a marsupial, the grey short-tailed opossum (Monodelphis domestica). We resolve the developmental trajectory and transcriptional signatures of the epiblast, primitive endoderm and trophectoderm, and identify deeply conserved lineage-specific markers that pre-date the eutherian-marsupial divergence. RSX coating and inactivation of the X chromosome occurs early and rapidly. This observation supports the hypothesis that--in organisms with early X chromosome inactivation--imprinted X chromosome inactivation prevents biallelic X silencing. We identify XSR, an RSX antisense transcript expressed from the active X chromosome, as a candidate for the regulator of imprinted X chromosome inactivation. Our datasets provide insights into the evolution of mammalian embryogenesis and X dosage compensation. Single-cell RNA-sequencing analysis of embryogenesis and X chromosome inactivation in the opossum (Monodelphis domestica) resolves the developmental trajectory of a marsupial, and sheds light on the evolution of embryogenesis in mammals., Author(s): Shantha K. Mahadevaiah [sup.1] , Mahesh N. Sangrithi [sup.2] [sup.3] , Takayuki Hirota [sup.1] , James M. A. Turner [sup.1] Author Affiliations: (1) Sex Chromosome Biology Laboratory, The Francis [...]

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Describes a research project that studied the indexing of moving image collections for storage and retrieval. Highlights include techniques and tools used for representing the content of moving image collections that are indexed shot by shot; indexing languages used, including keywords, classification; thesauri, and subject headings; and lexical concepts among various tools. (LRW)