Predicting host range expansion in parasitic mites using a global mammalian-acarine dataset.

Multi-host parasites pose greater health risks to wildlife, livestock, and humans than single-host parasites, yet our understanding of how ecological and biological factors influence a parasite's host range remains limited. Here, we assemble the largest and most complete dataset on permanently parasitic mammalian mites and build a predictive model assessing the probability of single-host parasites to become multi-hosts, while accounting for potentially unobserved host-parasite links and class imbalance. This model identifies statistically significant predictors related to parasites, hosts, climate, and habitat disturbance. The most important predictors include the parasite's contact level with the host immune system and two variables characterizing host phylogenetic similarity and spatial co-distribution. Our model reveals an overrepresentation of mites associated with Rodentia (rodents), Chiroptera (bats), and Carnivora in the multi-host risk group. This highlights both the potential vulnerability of these hosts to parasitic infestations and the risk of serving as reservoirs of parasites for new hosts. In addition, we find independent macroevolutionary evidence that supports our prediction of several single-host species of Notoedres, the bat skin parasites, to be in the multi-host risk group, demonstrating the forecasting potential of our model.

Molecular characterization of positively selected genes contributing aquatic adaptation in marine mammals.

BACKGROUND: Marine mammals, which have evolved independently into three distinct lineages, share common physiological features that contribute to their adaptation to the marine environment. OBJECTIVE: To identify positively selected genes (PSGs) for adaptation to the marine environment using available genomic data from three taxonomic orders: cetaceans, pinnipeds, and sirenians. METHODS: Based on the genomes within each group of Artiodactyla, Carnivora and Afrotheria, we performed selection analysis using the branch-site model in CODEML. RESULTS: Based on the branch-site model, 460, 614, and 359 PSGs were predicted for the cetaceans, pinnipeds, and sirenians, respectively. Functional enrichment analysis indicated that genes associated with hemostasis were positively selected across all lineages of marine mammals. We observed positive selection signals for the hemostasis and coagulation-related genes plasminogen activator, urokinase (PLAU), multimerin 1 (MMRN1), gamma-glutamyl carboxylase (GGCX), and platelet endothelial aggregation receptor 1 (PEAR1). Additionally, we found out that the sodium voltage-gated channel alpha subunit 9 (SCN9A), serine/arginine repetitive matrix 4 (SRRM4), and Ki-ras-induced actin-interacting protein (KRAP) are under positive selection pressure and are associated with cognition, neurite outgrowth, and IP3-mediated Ca2 + release, respectively. CONCLUSION: This study will contribute to our understanding of the adaptive evolution of marine mammals by providing information on a group of candidate genes that are predicted to influence adaptation to aquatic environments, as well as their functional characteristics.

Evolutionary patterns of cat-like carnivorans unveil drivers of the sabertooth morphology.

The sabertooth morphology stands as a classic case of convergence, manifesting recurrently across various vertebrate groups, prominently within two carnivorans clades: felids and nimravids. Nonetheless, the evolutionary mechanisms driving these recurring phenotypes remain insufficiently understood, lacking a robust phylogenetic and spatiotemporal framework. We reconstruct the tempo and mode of craniomandibular evolution of Felidae and Nimravidae and evaluate the strength of the dichotomy between conical and saber-toothed species, as well as within saber-toothed morphotypes. To do so, we investigate morphological variation, convergence, phenotypic integration, and evolutionary rates, employing a comprehensive dataset of nearly 200 3D models encompassing mandibles and crania from both extinct and extant feline-like carnivorans, spanning their entire evolutionary timeline. Our results reject the hypothesis of a distinctive sabertooth morphology, revealing instead a continuous spectrum of feline-like phenotypes in both the cranium and mandible, with sporadic instances of unequivocal convergence. Disparity peaked at the end of the Miocene and is usually higher in clades containing taxa with extreme sabertoothed adaptations. We show that taxa with saberteeth exhibit a lower degree of craniomandibular integration, allowing to exhibit a greater range of phenotypes. Those same groups usually show a burst of morphological evolutionary rate at the beginning of their evolutionary history. Consequently, we propose that a reduced degree of integration coupled with rapid evolutionary rates emerge as key components in the development of a sabertooth morphology in multiple clades.

The reorganization of predator-prey networks over 20 million years explains extinction patterns of mammalian carnivores.

Linking the species interactions occurring at the scale of local communities to their potential impact at evolutionary timescales is challenging. Here, we used the high-resolution fossil record of mammals from the Iberian Peninsula to reconstruct a timeseries of trophic networks spanning more than 20 million years and asked whether predator-prey interactions affected regional extinction patterns. We found that, despite small changes in species richness, trophic networks showed long-term trends, gradually losing interactions and becoming sparser towards the present. This restructuring of the ecological networks was driven by the loss of medium-sized herbivores, which reduced prey availability for predators. The decrease in prey availability was associated with predator longevity, such that predators with less available prey had greater extinction risk. These results not only reveal long-term trends in network structure but suggest that prey species richness in ecological communities may shape large scale patterns of extinction and persistence among predators.

Redescription of adults and first description of the larva of Haemaphysalis (Rhipistoma) adleri Feldman-Muhsam, 1951 (Acari: Ixodidae), parasite of carnivorans in Western Asia.

The adults of Haemaphysalis (Rhipistoma) adleri Feldman-Muhsam, 1951 (Acari: Ixodidae) are redescribed and the larva of this species is described for the first time here. The adults of H. adleri that we studied were collected from various canid, felid and hyaenid carnivorans (Carnivora: Canidae, Felidae, Hyaenidae) as well as a hedgehog (Erinaceomorpha: Erinaceidae) in Iraq, Israel and West Bank. The males, females and larvae of H. adleri can be differentiated from Haemaphysalis (Rhipistoma) species occurring in the Palearctic portion of West Asia and Egypt as well those in the H. asiatica subgroup by the length of idiosomal setae, development and size of spurs on palpi, dental formula on the hypostome and size of spur on coxae. A lectotype of H. adleri has been designated and the geographic distribution and hosts of this tick species are discussed.

The influence of the land-to-sea macroevolutionary transition on vertebral column disparification in Pinnipedia.

The repeated returns of vertebrates to the marine ecosystems since the Triassic serve as an evolutionary model to understand macroevolutionary change. Here we investigate the effects of the land-to-sea transition on disparity and constraint of the vertebral column in aquatic carnivorans (Carnivora; Pinnipedia) to assess how their functional diversity and evolutionary innovations influenced major radiations of crown pinnipeds. We use three-dimensional geometric morphometrics and multivariate analysis for high-dimensional data under a phylogenetic framework to quantify vertebral size and shape in living and extinct pinnipeds. Our analysis demonstrates an important shift in vertebral column evolution by 10-12 million years ago, from an unconstrained to a constrained evolutionary scenario, a point of time that coincides with the major radiation of crown pinnipeds. Moreover, we also demonstrate that the axial skeleton of phocids and otariids followed a different path of morphological evolution that was probably driven by their specialized locomotor strategies. Despite this, we found a significant effect of habitat preference (coastal versus pelagic) on vertebral morphology of crown taxa regardless of the family they belong. In summary, our analysis provides insights into how the land-to-sea transition influenced the complex evolutionary history of pinniped vertebral morphology.

Human habitat modification, not apex scavenger decline, drives isotopic niche variation in a carnivore community.

Top carnivores can influence the structure of ecological communities, primarily through competition and predation; however, communities are also influenced by bottom-up forces such as anthropogenic habitat disturbance. Top carnivore declines will likely alter competitive dynamics within and amongst sympatric carnivore species. Increasing intraspecific competition is generally predicted to drive niche expansion and/or individual specialisation, while interspecific competition tends to constrain niches. Using stable isotope analysis of whiskers, we studied the effects of Tasmanian devil Sarcophilus harrisii declines upon the population- and individual-level isotopic niches of Tasmanian devils and sympatric spotted-tailed quolls Dasyurus maculatus subsp. maculatus. We investigated whether time since the onset of devil decline (a proxy for severity of decline) and landscape characteristics affected the isotopic niche breadth and overlap of devil and quoll populations. We quantified individual isotopic niche breadth for a subset of Tasmanian devils and spotted-tailed quolls and assessed whether between-site population niche variation was driven by individual-level specialisation. Tasmanian devils and spotted-tailed quolls demonstrated smaller population-level isotopic niche breadths with increasing human-modified habitat, while time since the onset of devil decline had no effect on population-level niche breadth or interspecific niche overlap. Individual isotopic niche breadths of Tasmanian devils and spotted-tailed quolls were narrower in human-modified landscapes, likely driving population isotopic niche contraction, however, the degree of individuals' specialisation relative to one another remained constant. Our results suggest that across varied landscapes, mammalian carnivore niches can be more sensitive to the bottom-up forces of anthropogenic habitat disturbance than to the top-down effects of top carnivore decline.

Mesocarnivores vary in their spatiotemporal avoidance strategies at communications hubs of an apex carnivore.

Mesocarnivores face interspecific competition and risk intraguild predation when sharing resources with apex carnivores. Within a landscape, carnivores across trophic levels may use the same communication hubs, which provide a mix of risks (injury/death) and rewards (gaining information) for subordinate species. We predicted that mesocarnivores would employ different strategies to avoid apex carnivores at shared communication hubs, depending on their trophic position. To test our prediction, we examined how different subordinate carnivore species in the Santa Cruz Mountains of California, USA, manage spatial overlap with pumas (Puma concolor), both at communication hubs and across a landscape-level camera trap array. We estimated species-specific occurrence, visitation rates, temporal overlap, and Avoidance-Attraction Ratios from camera traps and tested for differences between the two types of sites. We found that mesocarnivores generally avoided pumas at communication hubs, and this became more pronounced when pumas scent-marked during their most recent visit. Coyotes (Canis latrans), the pumas' closest subordinate competitor in our system, exhibited the strongest avoidance at communication hubs. Gray foxes (Urocyon cinereoargenteus) avoided pumas the least, which may suggest possible benefits from pumas suppressing coyotes. Overall, mesocarnivores exhibited various spatiotemporal avoidance strategies at communication hubs rather than outright avoidance, likely because they benefit from information gained while 'eavesdropping' on puma activity. Variability in avoidance strategies may be due to differential predation risks, as apex carnivores often interact more aggressively with their closest competitors. Combined, our results show how apex carnivores trigger complex species interactions across the entire carnivore guild and how trophic position determines behavioral responses and subsequent space use of subordinate mesocarnivores across the landscape.

Carnivore coexistence without competition: giant otters are more nocturnal around dens than sympatric neotropical otters.

Nocturnal activity of tropical otters is rarely reported. To date no studies have documented den use by sympatric giant (Pteronura brasiliensis) and neotropical otters (Lontra longicaudis). We used camera-traps to monitor den use by sympatric otters along an equatorial Amazonian river. Camera-traps provided evidence that giant otters were more nocturnal around dens than sympatric neotropical otters. Nocturnal activity was recorded in 11% of giant otter photos (n = 14 of 125 photos), but was recorded only once for neotropical otters. Den use by giant and neotropical otters overlapped spatially and temporally but not concurrently. We hypothesize that previously reported nocturnal activity in neotropical otters is facilitated by the absence or low density of giant otters. Our results also underscore the need to use complementary techniques together with den counts for monitoring otters as sympatric species can use the same dens.

Wildlife parasitology: sample collection and processing, diagnostic constraints, and methodological challenges in terrestrial carnivores.

Wild terrestrial carnivores play a crucial role as reservoir, maintenance, and spillover hosts for a wide parasite variety. They may harbor, shed, and transmit zoonotic parasites and parasites of veterinary importance for domestic hosts. Although wild carnivores are globally distributed and comprise many different species, some living in close proximity to human settlements, only a few studies have investigated parasites of wild terrestrial carnivores using non-specific techniques. Access to samples of wild carnivores may be challenging as some species are protected, and others are secretive, possibly explaining the data paucity. Considering the importance of wild carnivores' health and ecological role, combined with the lack of specific diagnostic methodologies, this review aims to offer an overview of the diagnostic methods for parasite investigation in wild terrestrial carnivores, providing the precise techniques for collection and analysis of fecal, blood, and tissue samples, the environmental impact on said samples, and the limitations researchers currently face in analyzing samples of wild terrestrial carnivores. In addition, this paper offers some crucial information on how different environmental factors affect parasite detection postmortem and how insects can be used to estimate the time of death with a specific highlight on insect larvae. The paper contains a literature review of available procedures and emphasizes the need for diagnostic method standardization in wild terrestrial carnivores.

Computer vision enables taxon-specific identification of African carnivore tooth marks on bone.

Taphonomic works aim at discovering how paleontological and archaeofaunal assemblages were formed. They also aim at determining how hominin fossils were preserved or destroyed. Hominins and other mammal carnivores have been co-evolving, at least during the past two million years, and their potential interactions determined the evolution of human behavior. In order to understand all this, taxon-specific carnivore agency must be effectively identified in the fossil record. Until now, taphonomists have been able to determine, to some degree, hominin and carnivore inputs in site formation, and their interactions in the modification of part of those assemblages. However, the inability to determine agency more specifically has hampered the development of taphonomic research, whose methods are virtually identical to those used several decades ago (lagged by a high degree of subjectivity). A call for more objective and agent-specific methods would be a major contribution to the advancement of taphonomic research. Here, we present one of these advances. The use of computer vision (CV) on a large data set of images of tooth marks has enabled the objective discrimination of taxon-specific carnivore agency up to 88% of the testing sample. We highlight the significance of this method in an interdisciplinary interplay between traditional taphonomic-paleontological analysis and artificial intelligence-based computer science. The new questions that can be addressed with this will certainly bring important changes to several ideas on important aspects of the human evolutionary process.

Diversity of Trichinella species in carnivores from Bosnia and Herzegovina.

BACKGROUND: In Bosnia and Herzegovina, domestic and wild carnivores represent a significant driver for the transmission and ecology of zoonotic pathogens, especially those of parasitic aetiology. Nevertheless, there is no systematic research of Trichinella species in animals that have been conducted in Bosnia and Herzegovina, even though trichinellosis is considered the most important parasitic zoonosis. The available results of the few studies carried out in Bosnia and Herzegovina are mainly related to the confirmation of parasitic larvae in the musculature of domestic pigs and wild boars or data related to trichinellosis in humans. The objective of our study was to present the findings of a comprehensive investigation into the species composition of Trichinella among 11 carnivorous species within the territory of Bosnia and Herzegovina, as follows: red fox (Vulpes vulpes), grey wolf (Canis lupus), brown bear (Ursus arctos), wildcat (Felis silvestris), pine marten (Martes martes), European badger (Meles meles), weasel (Mustela nivalis), European polecat (Mustela putorius), Eurasian lynx (Lynx lynx), but also dog (Canis lupus familiaris) and cat (Felis catus). RESULTS: In the period 2013-2023, carnivore musculature samples (n = 629), each consisting of 10 g of muscle tissue, were taken post-mortem and individually examined using the artificial digestion method. In the positive samples (n = 128), molecular genotyping and identification of parasitic larvae of Trichinella spp. were performed using a PCR-based technique up to the species/genotype level. Positive samples were used for basic PCR detection of the genus Trichinella (rrnS rt-PCR technique) and genotyping (rrnl-EVS rt-PCR technique). The Trichinella infection was documented for the first time in Bosnia and Herzegovina among red foxes, grey wolves, brown bears, dogs, badgers and Eurasian lynx, with a frequency rate of 20.3%. Additionally, the presence of T. britovi infection was newly confirmed in Bosnia and Herzegovina, marking the initial documented cases. Furthermore, both T. britovi and T. pseudospiralis infections were observed in the wildcat population, whereas T. britovi and T. spiralis infections were detected in pine martens. Consistent with previous research, our findings align particularly regarding carnivores, with data from other countries such as Germany, Finland, Romania, Poland and Spain, where T. britovi exhibits a wider distribution (62.5-100%) compared to T. spiralis (0.0-37.5%). T. britovi is more common among sylvatic carnivores (89.0%), while T. spiralis prevails in wild boars (62.0%), domestic swine (82.0%) and rodents (75.0%). CONCLUSION: The results of our study represent the first molecular identification of species of the genus Trichinella in Bosnia and Herzegovina. Additionally, our findings underscore the necessity for targeted epidemiological studies to thoroughly assess trichinellosis prevalence across diverse animal populations. Considering the relatively high frequency of trichinellosis infection in investigated animal species and its public health implications, there is an evident need for establishing an effective trichinellosis surveillance system in Bosnia and Herzegovina.

Using global remote camera data of a solitary species complex to evaluate the drivers of group formation.

The social system of animals involves a complex interplay between physiology, natural history, and the environment. Long relied upon discrete categorizations of "social" and "solitary" inhibit our capacity to understand species and their interactions with the world around them. Here, we use a globally distributed camera trapping dataset to test the drivers of aggregating into groups in a species complex (martens and relatives, family Mustelidae, Order Carnivora) assumed to be obligately solitary. We use a simple quantification, the probability of being detected in a group, that was applied across our globally derived camera trap dataset. Using a series of binomial generalized mixed-effects models applied to a dataset of 16,483 independent detections across 17 countries on four continents we test explicit hypotheses about potential drivers of group formation. We observe a wide range of probabilities of being detected in groups within the solitary model system, with the probability of aggregating in groups varying by more than an order of magnitude. We demonstrate that a species' context-dependent proclivity toward aggregating in groups is underpinned by a range of resource-related factors, primarily the distribution of resources, with increasing patchiness of resources facilitating group formation, as well as interactions between environmental conditions (resource constancy/winter severity) and physiology (energy storage capabilities). The wide variation in propensities to aggregate with conspecifics observed here highlights how continued failure to recognize complexities in the social behaviors of apparently solitary species limits our understanding not only of the individual species but also the causes and consequences of group formation.

Beyond the kill: The allometry of predation behaviours among large carnivores.

The costs of foraging can be high while also carrying significant risks, especially for consumers feeding at the top of the food chain. To mitigate these risks, many predators supplement active hunting with scavenging and kleptoparasitic behaviours, in some cases specializing in these alternative modes of predation. The factors that drive differential utilization of these tactics from species to species are not well understood. Here, we use an energetics approach to investigate the survival advantages of hunting, scavenging and kleptoparasitism as a function of predator, prey and potential competitor body sizes for terrestrial mammalian carnivores. The results of our framework reveal that predator tactics become more diverse closer to starvation, while the deployment of scavenging and kleptoparasitism is strongly constrained by the ratio of predator to prey body size. Our model accurately predicts a behavioural transition away from hunting towards alternative modes of predation with increasing prey size for predators spanning an order of magnitude in body size, closely matching observational data across a range of species. We then show that this behavioural boundary follows an allometric power-law scaling relationship where the predator size scales with an exponent nearing 3/4 with prey size, meaning that this behavioural switch occurs at relatively larger threshold prey body size for larger carnivores. We suggest that our approach may provide a holistic framework for guiding future observational efforts exploring the diverse array of predator foraging behaviours.

Fleas of wild carnivores in Romania: diversity, distribution, and host-associations.

BACKGROUND: Fleas are important hematophagous insects, infesting mammals and birds with a worldwide distribution. Fleas of medical importance have been reported from various carnivores worldwide, such as felids, canids, or mustelids. Romania hosts a wide carnivore diversity, but very little is known about flea species that parasitize these animals in Romania. This study aimed to provide a better understanding of the fleas' diversity and their distribution in a relatively large and diverse number of wild carnivore hosts from Romania. METHODS: From 2013 to 2021, 282 carcasses of wild carnivores from different locations in Romania were collected and examined for the presence of ectoparasites. All collected fleas were morphologically identified using specific keys and descriptions. An analysis of the co-occurrence networks was performed. RESULTS: A total of 11 flea species were identified: Pulex irritans (41.09%), Paraceras melis (20.11%), Ctenocephalides felis (7.33%), Ctenocephalides canis (7.83%), Monopsyllus sciurorum (11.11%), Chaetopsylla trichosa (21.96%), Chaetopsylla homoea (5.5%), Chaetopsylla tuberculaticeps (100%), Chaetopsylla rothschildi (13.33%), Chaetopsylla sp. (14.34%), Chaetopsylla globiceps (5.12%), Echidnophaga gallinacea (10%). The statistical analyses showed a significant difference between the infestation of Martes foina with females being more frequently infected than males (66% versus 33%). Paraceras melis infesting Meles meles had a significantly higher prevalence in female badgers than in males (× 2 = 7.7977, P < 0.01) and higher intensities of infestations in males than in females (t = 1.871, P < 0.05). CONCLUSIONS: This is the first large-scale study investigating the distribution and diversity of flea species infesting wild carnivores in Romania. Three flea species were identified for the first time in Romania (E. gallinacea, C. homoea, and C. tuberculaticeps).

Brown bear digging decreases tree growth: Implication for ecological role of top predators in anthropogenic landscapes.

Large carnivores have recently increased in number and recolonized in human-dominated landscapes; however, their ecological roles in these landscapes have not been well studied. In the Shiretoko World Heritage (SWH) site, brown bears have recolonized a previously abandoned mosaic landscape of natural forests and conifer plantations after land abandonment. We previously reported that the bears had recently begun to dig for cicada nymphs in association with the creation of larch plantations. As a result, this digging activity decreased soil nutrients. To deepen the understanding of the novel ecological role of brown bears within human-modified landscapes, we examined the impacts of brown bear digging on the growth of larch trees. We found that brown bear digging decreased fine root biomass of larch, soil water, and nitrogen availability. Brown bear digging negatively affected needle nitrogen content, but not carbon isotope ratios, a water stress index of trees. Tree ring data suggest that digging negatively affected the radial growth of larches. The results imply that digging decreases tree growth due to limited soil nitrogen uptake. Our findings indicate that the ecological roles of large carnivores may differ between natural and anthropogenic landscapes.

LISTERIA MONOCYTOGENES INFECTION IN FREE-RANGING RED FOXES (VULPES VULPES) AND EURASIAN LYNX (LYNX LYNX) IN SWITZERLAND.

Listeria monocytogenes is an ubiquitous environmental saprophytic bacterium causing listeriosis in domestic animals, humans, and occasionally wildlife. In animals, this foodborne zoonotic disease mainly occurs in ruminants and it is rare in carnivores. Seven red foxes (Vulpes vulpes) and one Eurasian lynx (Lynx lynx) were diagnosed with listeriosis between 2010 and 2021 at the Institute for Fish and Wildlife Health, Bern, Switzerland. Necropsy and histopathology revealed meningitis (six of seven red foxes), hepatitis (six of seven red foxes), pneumonia (five of seven red foxes), splenitis (two of seven red foxes) and splenomegaly (the Eurasian lynx, two of seven red foxes). Listeria monocytogenes was isolated from either lung, spleen, liver, or kidney of all animals. Serotyping detected L. monocytogenes serotype 1/2a in five red foxes and the Eurasian lynx and serotype 4b in two red foxes. Six red foxes were positive for canine distemper virus (CDV) by polymerase chain reaction, whereas the Eurasian lynx and one red fox were negative. One red fox that was positive for CDV and listeriosis was also diagnosed with salmonellosis. The identified L. monocytogenes serotypes are among the three most frequently isolated serotypes (1/2a, 1/2b, and 4b) from food or the food production environment and those that cause most listeriosis cases in humans and animals. Coinfection with CDV in six red foxes questions the role of CDV as potential predisposing factor for septicemic listeriosis. The detection of listeriosis in the regionally endangered Eurasian lynx and in carnivores highly abundant in urban settings, such as red foxes, reinforces the importance of wildlife health surveillance in a One Health context and adds the Eurasian lynx to the list of carnivores susceptible to the disease. Further investigations are required to assess the prevalence and epidemiology of L. monocytogenes in free-ranging carnivores and its interaction with CDV.

Safety and immunogenicity of an adjuvanted recombinant spike protein-based severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) vaccine, SpikeVet™, in selected Carnivora, Primates and Artiodactyla in Australian zoos.

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) can infect a broad range of animal species and has been associated with severe disease in some taxa. Few studies have evaluated optimal strategies to mitigate the risk to susceptible zoo animals. This study evaluated the safety and immunogenicity of a protein-based veterinary SARS-CoV-2 vaccine (SpikeVet™) in zoo animals. Two to three doses of SpikeVet™ were administered intramuscularly or subcutaneously 3-4 weeks apart to 354 zoo animals representing 38 species. SpikeVet™ was very well tolerated across all species. Minor adverse effects were observed in 1.69% of animals vaccinated, or 1.04% of vaccine doses administered. Preliminary immunogenicity analyses in representative carnivores (meerkats, lions) and an artiodactylid (domestic goat) showed SpikeVet™-immunized animals developed serum antibodies able to neutralize a range of SARS-CoV-2 variants, including the vaccine-homologous Wuhan and Mu variants, as well as vaccine-heterologous Omicron BA.2 and XBB.1 strains. Prior to vaccination, all eight lions were seropositive for Wuhan strain by surrogate viral neutralization testing, suggesting past infection with SARS-CoV-2 or cross-reactive antibodies generated by another closely related coronavirus. These results from a range of zoo species support the ongoing development of SpikeVet™ as a safe and effective veterinary SARS-CoV-2 vaccine.

Positive selection in gamete interaction proteins in Carnivora.

The absence of robust interspecific isolation barriers among pantherines, including the iconic South American jaguar (Panthera onca), led us to study molecular evolution of typically rapidly evolving reproductive proteins within this subfamily and related groups. In this study, we delved into the evolutionary forces acting on the zona pellucida (ZP) gamete interaction protein family and the sperm-oocyte fusion protein pair IZUMO1-JUNO across the Carnivora order, distinguishing between Caniformia and Feliformia suborders and anticipating few significant diversifying changes in the Pantherinae subfamily. A chromosome-resolved jaguar genome assembly facilitated coding sequences, enabling the reconstruction of protein evolutionary histories. Examining sequence variability across more than 30 Carnivora species revealed that Feliformia exhibited significantly lower diversity compared to its sister taxa, Caniformia. Molecular evolution analyses of ZP2 and ZP3, subunits directly involved in sperm-recognition, unveiled diversifying positive selection in Feliformia, Caniformia and Pantherinae, although no significant changes were linked to sperm binding. Structural cross-linking ZP subunits, ZP4 and ZP1 exhibited lower levels or complete absence of positive selection. Notably, the fusion protein IZUMO1 displayed prominent positive selection signatures and sites in basal lineages of both Caniformia and Feliformia, extending along the Caniformia subtree but absent in Pantherinae. Conversely, JUNO did not exhibit any positive selection signatures across tested lineages and clades. Eight Caniformia-specific positive selected sites in IZUMO1 were detected within two JUNO-interaction clusters. Our findings provide for the first time insights into the evolutionary trajectories of ZP proteins and the IZUMO1-JUNO gamete interaction pair within the Carnivora order.

An integrated population model reveals source-sink dynamics for competitively subordinate African wild dogs linked to anthropogenic prey depletion.

Many African large carnivore populations are declining due to decline of the herbivore populations on which they depend. The densities of apex carnivores like the lion and spotted hyena correlate strongly with prey density, but competitively subordinate carnivores like the African wild dog benefit from competitive release when the density of apex carnivores is low, so the expected effect of a simultaneous decrease in resources and dominant competitors is not obvious. Wild dogs in Zambia's South Luangwa Valley Ecosystem occupy four ecologically similar areas with well-described differences in the densities of prey and dominant competitors due to spatial variation in illegal offtake. We used long-term monitoring data to fit a Bayesian integrated population model (IPM) of the demography and dynamics of wild dogs in these four regions. The IPM used Leslie projection to link a Cormack-Jolly-Seber model of area-specific survival (allowing for individual heterogeneity in detection), a zero-inflated Poisson model of area-specific fecundity and a state-space model of population size that used estimates from a closed mark-capture model as the counts from which (latent) population size was estimated. The IPM showed that both survival and reproduction were lowest in the region with the lowest density of preferred prey (puku, Kobus vardonii and impala, Aepyceros melampus), despite little use of this area by lions. Survival and reproduction were highest in the region with the highest prey density and intermediate in the two regions with intermediate prey density. The population growth rate ( λ ) was positive for the population as a whole, strongly positive in the region with the highest prey density and strongly negative in the region with the lowest prey density. It has long been thought that the benefits of competitive release protect African wild dogs from the costs of low prey density. Our results show that the costs of prey depletion overwhelm the benefits of competitive release and cause local population decline where anthropogenic prey depletion is strong. Because competition is important in many guilds and humans are affecting resources of many types, it is likely that similarly fundamental shifts in population limitation are arising in many systems.