The Symptom Structure and Causal Relationships of Comorbid Anxiety and Depression Among Chinese Primary and Middle School Teachers: A Network Analysis.

Background: In China, as educational reforms progress, the characteristics of teachers' work have undergone significant changes, resulting in extremely high levels of stress that can trigger anxiety and depression. Anxiety and depression often co-occur, with two mainstream theories explaining this co-existence: the tripartite model and the diathesis-stress model. However, systematic research focusing on this population is relatively scarce, and the applicability of these models has not been thoroughly tested. This study aims to use network analysis methods to examine the interactions between symptoms and analyze the co-existence of anxiety and depression, thereby expanding the research on teachers. Methods: Data were provided by the Science Database of People Mental Health, which includes 1670 teachers with a mean age of 30.01. The Self-Rating Anxiety Scale and Self-Rating Depression Scale were used to estimate the network structures of anxiety and depression, respectively. Shared symptoms between depression and anxiety were identified using network analysis and clique percolation methods. Bayesian Networks was used to estimate causal relationships between symptoms. Data were analyzed using R packages. Network structure was constructed with the qgraph package, node centrality and bridge symptoms were evaluated using the networktools package, and network stability was measured via the bootnet package. The Clique Percolation method was implemented with the CliqurPercolation package, and Bayesian network modeling was performed via the Bnlearn package. Results: Dizziness and Easy Fatigability & Weakness were central symptoms in the network. Bridging strength results showed that, the important bridging symptoms included Tachycardia, Depressed Affect, Fatigue, Crying Spell, Easy Fatigability & Weakness, Nightmares, Face Flushing, and Sweating were the strong bridging symptoms. Additionally, Sleep Disturbance played a key mediating role. Depressed Affect and Dissatisfaction were activation symptoms for anxiety-depression co-existence. Conclusion: Using network analysis, this study elucidated core, bridging, and shared symptoms, as well as potential causal pathways between anxiety and depression. Specifically, somatic symptoms are crucial in maintaining and developing the anxiety-depression network among teachers. Sleep disturbance serves as the sole gateway for mild symptoms to develop into other communities. The Bayesian network identified two key activating symptoms within the teacher anxiety-depression network, validating the applicability of the tripartite model among teachers.

Symbiotic probiotic communities with multiple targets successfully combat obesity in high-fat-diet-fed mice.

Probiotics hold great potential for treating metabolic diseases such as obesity. Given the complex and multifactorial nature of these diseases, research on probiotic combination with multiple targets has become popular. Here, we choose four obesity-related targets to perform high-throughput screening, including pancreatic lipase activity, bile salt hydrolase activity, glucagon-like peptide-1 secretion and adipocyte differentiation. Then, we obtained 649 multi-strain combinations with the requirement that each must cover all these targets in principle. After in vitro co-culture and in vivo co-colonization experiments, only four (<0.7%) combinations were selected as symbiotic probiotic communities (SPCs). Next, genome-scale metabolic model analysis revealed that these SPCs showed lower metabolic resource overlap and higher metabolic interaction potential involving amino acid metabolism (Ammonium, L-Lysine, etc.) and energy metabolism (Phosphate, etc.). Further animal experiments demonstrated that all SPCs exhibited a good safety profile and excellent effects in improving obesity and associated glucose metabolism disruptions and depression-like behaviors in high-fat-diet-fed mice. This anti-obesity improvement was achieved through reduced cholesterol level, fat accumulation and inhibited adipocyte differentiation. Taken together, our study provides a new perspective for designing multi-strain combinations, which may facilitate greater therapeutic effect on obesity and other complex diseases in the future.

Metabolic Trade-Offs Can Reverse the Resource-Diversity Relationship.

AbstractFor species that partition resources, the classic expectation is that increasing resource diversity allows for increased species diversity. On the other hand, for neutral species, such as those competing equally for a single resource, diversity reflects a balance between the rate of introduction of novelty (e.g., by immigration or speciation) and the rate of extinction. Recent models of microbial metabolism have identified scenarios where metabolic trade-offs among species partitioning multiple resources can produce emergent neutral-like dynamics. In this hybrid scenario, one might expect that both resource diversity and immigration will act to boost species diversity. We show, however, that the reverse may be true: when metabolic trade-offs hold and population sizes are sufficiently large, increasing resource diversity can act to reduce species diversity, sometimes drastically. This reversal is explained by a generic transition between neutral- and niche-like dynamics, driven by the diversity of resources. The inverted resource-diversity relationship that results may be a signature of consumer-resource systems with strong metabolic trade-offs.

A Case With Gallbladder Villous Tubular Adenoma With High-Grade Intraepithelial Neoplasia Combined With Rectal Villous Tubular Adenocarcinoma.

We present the rare case of a 79-year-old female patient with the coexistence of gallbladder villous tubular adenoma and rectal villous tubular adenocarcinoma. She initially presented with blood in the stool, prompting a diagnosis of rectal cancer. Further examination revealed findings suggestive of a gallbladder pathology. Subsequent imaging and histopathological analyses confirmed the presence of a gallbladder villous tubular adenoma, high-grade intraepithelial neoplasia, and rectal villous tubular adenocarcinoma. Surgical interventions included laparoscopic radical resection of the rectal cancer and cholecystectomy. Immunohistochemical examination differentiated between the two distinct adenomatous conditions. This case underscores the importance of thorough evaluation and multidisciplinary approaches for accurate diagnosis and management of complex presentations of gastrointestinal neoplasms.

Functional Traits Predict Outcomes of Current and Novel Competition Under Warmer Climate.

Functional traits offer a potential avenue to generalize and forecast the impacts of changing competition on plant communities, including changing outcomes of competition among species that currently interact (current competition) or that will interact in the future following range shifts (novel competition). However, it remains unclear how well traits explain variation in the outcomes of current and novel competition as well as the underlying processes determining coexistence or competitive exclusion, under changing climate. Here, we interacted pairs of high and low-elevation species in three sites across an elevation gradient in the Swiss Alps. For each species pair, we quantified the population-level outcomes of competition (invasion growth rates), relative fitness differences, and niche overlap and related these to 15 functional traits that were measured in each site. Most traits were significantly associated with invasion growth rates at the low elevation, where species had greater relative fitness differences, but these associations were much weaker towards higher elevations. This appears to be because traits, particularly those associated with light competition, captured species' relative fitness differences at lower elevations, but not at the high elevation site, highlighting that the predictive ability of traits can depend on environmental context. The amplified relative fitness differences towards lower elevations suggest that climate warming may increase the likelihood of competitive exclusion. In addition, novel competitors tended to show greater niche overlap than current competitors, leading to stronger overall competitive effects. However, in general, trait differences predicted competitive outcomes of novel and current competitors similarly well, suggesting that traits can predict interactions between species that do not yet interact. Our study reinforces the importance of considering changing interactions for predicting species responses to climate change and provides experimental evidence supporting the usefulness of functional trait differences in forecasting the impacts of future plant interactions under changing climate.

Quantifying the Ecological Performance of Migratory Bird Conservation: Evidence from Poyang Lake Wetlands in China.

Protected areas are essential for the conservation of biodiversity. However, the rapid expansion of urbanization and the intensification of human activities have significantly disrupted environmental integrity, leading to a continuous deterioration in both the quantity and quality of large ecological patches. This has further diminished the connectivity among ecological patches, leading to significant consequences for regional biodiversity conservation. Taking Poyang Lake as a case study, which serves as a crucial wintering habitat for migratory birds along the East Asia-Australasia flyway, this research employs ArcMap technology. It considers various factors including land use type, slope, and elevation to evaluate habitat quality and degradation through the application of the InVEST model. Additionally, the study utilizes the minimum cumulative resistance (MCR) model alongside circuit theory to delineate ecological corridors within the area and to establish a comprehensive ecological network system. The research results in this paper are as follows. (i) During the period from 2000 to 2020, there was an overall decline in habitat quality within the study area, indicating a clear trend of habitat degradation. However, it is worth noting that there was an increase in habitat quality in certain local areas within the protected area. (ii) The ecological resistance values in the core area of the migratory bird reserve in Poyang Lake are generally low. However, the ecological resistance values of the habitats have shown a consistent increase from 2000 to 2020. Additionally, there has been a significant decrease in the density of ecological corridors during this time period. (iii) Over the period from 2000 to 2020, both the number and connectivity of ecological corridors decreased and their integrity and functionality degraded. Consequently, this weakened role of the ecological network has had implications for maintaining regional biodiversity and ecosystem service functions. The findings indicate two conclusions. (i) Ecological connectivity is essential for the conservation of migratory bird habitats. Strengthening control measures aimed at expanding ecological corridors can effectively safeguard flagship and umbrella species, thereby promoting biodiversity conservation. (ii) The establishment of ecological corridors can help reconcile conflicts between conservation efforts and development objectives. This reconciliation carries significant theoretical implications for fostering a harmonious coexistence between humans and birds in Poyang Lake's migratory bird sanctuary.

A Parasite Plant Promotes the Coexistence of Two Annual Plants.

Consumers can influence the competitive outcomes of prey species in various ways. Modern coexistence theory predicts that consumers can promote prey coexistence by preferably targeting a competitively superior one, thereby reducing fitness differences. However, previous studies yielded mixed conclusions. In this study, we tested the hypothesis that a parasitic annual plant, Cuscuta campestris, facilitates the coexistence of two common annual plants. We performed field surveys and parasitism experiments to parameterize a plant competition dynamics model. The model suggested a competition-defence tradeoff: the legume Lespedeza striata was a better competitor than the grass Setaria faberi, while it was more susceptible to the parasite. Moreover, an empirical host-parasite dynamics model, extended from the plant competition model, predicted their coexistence within broad, biologically reasonable ranges of parameters. This work provides field evidence of the coexisting-promoting role of a parasitic plant, as caused by stabilising feedback between host and parasite densities.

Effects of the co-exposure of microplastic/nanoplastic and heavy metal on plants: Using CiteSpace, meta-analysis, and machine learning.

Micro/nanoplastics (MNPs) and heavy metals (HMs) coexist worldwide. Existing studies have reported different or even contradictory toxic effects of co-exposure to MNPs and HMs on plants, which may be related to various influencing factors. In this study, existing publications were searched and analyzed using CiteSpace, meta-analysis, and machine learning. CiteSpace analysis showed that this research field was still in the nascent stage, and hotspots in this field included accumulation, cadmium (Cd), growth, and combined toxicity. Meta-analysis revealed the differential association of seven influencing factors (MNP size, pollutant treatment duration, cultivation media, plant species, MNP type, HM concentration, and MNP concentration) and 8 physiological parameters receiving the most attention. Co-exposure of the two contaminants had stronger toxic effects than HM treatment alone, and phytotoxicity was generally enhanced with increasing concentrations and longer exposure durations, especially when using nanoparticles, hydroponic medium, dicotyledons producing stronger toxic effects than microplastics, soil-based medium, and monocotyledons. Dry and fresh weight analysis showed that co-exposure to MNPs and Cd resulted in significant phytotoxicity in all classifications. Concerning the MNP types, polyolefins partially attenuated plant toxicity, but both modified polystyrene (PS) and biodegradable polymers exacerbated joint phytotoxicity. Finally, machine learning was used to fit and predict plant HM concentrations, showing five classifications with an accuracy over 80 %, implying that the polynomial regression model could be used to predict HM content in plants under complex pollution conditions. Overall, this study identifies current knowledge gaps and provides guidance for future research.

Coexistence and genomics characterization of mcr-1 and extended-spectrum-ß-lactamase-producing Escherichia coli, an emerging extensively drug-resistant bacteria from sheep in China.

The emergence of pathogens harboring multiple resistance genes poses a great threat to global public health. However, the coexistence of mobile resistance genes that provide resistance to both third-generation cephalosporins and colistin in sheep-origin Escherichia coli has not been previously investigated in China. This study is the first to characterize five E. coli isolates from sheep in Shaanxi province that harbor both Extended-Spectrum ß-Lactamase (ESBL) and mcr-1 resistance genes. The isolates were identified and characterized by Illumina sequencing, nanopore sequencing, bioinformatic analysis, conjugation experiments, and antimicrobial susceptibility testing. Genetic analysis revealed that blaCTX-M-55 gene, mediated by the IS26, was located on the IncFIB-IncFIC plasmid, while the mcr-1 gene was located on the IncI2(Delta) plasmid. Notably, two copies of blaCTX-M-55 gene were also identified on the chromosome of one isolate (SX45), facilitated by the ISEcp1 insertion sequence. Additionally, the plasmid pSX23-2 was identified as a complex plasmid derived through homologous recombination of pMG337 from E. coli (MK878890) and pZY-1 from Citrobacter freundii (CP055248). Data mining of publicly available databases revealed that isolates carrying both blaCTX-M-55 and mcr-1 genes have been found in humans, animals, and the environment, indicating the widespread presence of these critical resistance genes across different niches. Antimicrobial susceptibility testing showed that the five isolates were resistant to a nearly all tested antibiotics, except meropenem. Conjugative transfer experiments demonstrated that the IncFIB-IncFIC and IncI2(Delta) plasmids carrying mcr-1 and blaCTX-M-55 were capable of transferring between different sequence types (STs) of sheep-origin E. coli, including ST10, ST162, and ST457. This finding suggests the potential for wide dissemination of these resistance markers among diverse E. coli strains. Overall, the characterization of these ESBL and mcr-1 co-harboring isolates enhances our understanding of the spread of these resistance genes in sheep-origin E. coli. Global surveillance of these isolates, particularly within the One Health framework, is essential to monitor and mitigate the risks posed by the dissemination of these resistance genes across various settings.

Daily Activity Rhythms of Animals in the Southwest Mountains, China: Influences of Interspecific Relationships and Seasons.

Temporal and spatial factors regulate the interactions between apex predators, mesocarnivores, and herbivores. Prey adjust their activity patterns and spatial utilization based on predator activities; in turn, predators also adapt to the activities of their prey. To elucidate the factors influencing the daily activity rhythms of animals, 115 camera traps were established from September 2019 to June 2023 to assess the influences of interspecific relationships and seasons on the daily activity rhythms of animals in the southwest mountains of China. The species captured by the cameras included six Carnivora (such as Panthera pardus and Lynx lynx), six Artiodactyla (such as Moschus spp. and Rusa unicolor), one Primate (Macaca mulatta), and two Galliformes (Crossoptilon crossoptilon, Ithaginis cruentus). The results demonstrated that the 15 species exhibited different activity rhythms and peak activities to reduce intense resource competition. There were differences in the species' activity rhythms in different seasons, with competition among different species being more intense in the cold season than in the warm season. In predation relationships, the overlap coefficient in the cold season exceeded that of the warm season, possibly due to the abundant resources in summer and food scarcity in winter. In competitive relationships, 15 pairs of species exhibited significantly higher overlap coefficients in the cold season compared to the warm season, possibly due to increased demands for energy during the cold period or seasonal changes in predatory behavior. By analyzing the daily and seasonal activity patterns of dominant species in the study area, temporal niche overlaps were established to compare the competition levels between species. These findings indicate that the activity rhythms of the animals in this area not only result from evolutionary adaptation but are also influenced by season, food resources, and interspecific relationships (predation and competition). Thus, efforts should be made to reduce human interference, protect food resources in the winter, and monitor animals' interspecific relationships to protect animal diversity and maintain the stability of the ecosystem in this biodiversity hotspot in China.

Interspecific interactions among parasites in multiple infections.

Individual hosts and populations frequently harbour multiple parasite species simultaneously. Despite their commonness, the consequences of interspecific interactions among parasites for determining infection outcomes are still poorly understood. We review and propose several expectations for multiple infections involving different species. We highlight that interspecific interactions affect the outcome of competition within hosts and that heterospecific parasites engage in cotransmission, gene exchange, and reproductive interference. Studies specifically comparing intra- and inter-specific coinfections and knowledge from community ecology may be instrumental to fully understand the consequences of interspecific multiple infections for parasite life history, ecology, and evolution.

Host-specific monogeneans parasitizing freshwater fish: The ecology and evolution of host-parasite associations.

Monogenea (Platyhelminthes), mainly gill and fin ectoparasites of fish, are often recognized as host specific and morphologically and ecologically diverse. These parasites exhibit high species diversity at the level of host species or individual fish specimens. Using case studies, especially those widely performed in Dactylogyrus parasitizing cyprinoid fish, this article presents current knowledge on the ecology and evolution of congeneric gill monogeneans. The important aspects of the ecology of congeneric monogeneans are highlighted, in particular: host specificity expressed at several host levels (from strict specificity to phylogenetic specificity), microhabitat specificity expressed by restricted positions on fish gills to facilitate intraspecific mating, and the link between microhabitat preference and morphological adaptation (i.e., sclerotized structures of the haptor) or reproductive isolation. From the evolutionary perspective, this study focused on the processes of the speciation and diversification of congeneric monogeneans, highlighting the role of host switch as the most prominent coevolutionary event, accompanied in some cases mostly by intrahost speciation or cospeciation, as revealed by cophylogenetic studies. Here, important knowledge on evolutionary patterns of host specificity, microhabitat specificity, and morphological adaptation is presented. Host-specific monogeneans may represent an important tool for studying the historical biogeography of their hosts. Specifically, in the case of freshwater fish hosts exhibiting disjunctive distribution, they reflect both historical and contemporary contacts. The role of host-specific congeneric monogeneans in revealing historical intercontinental and intracontinental contacts between freshwater fish is highlighted. Finally, the importance of the role of genetic coadaptation, limiting the presence of host-specific monogeneans in hybrid fish, is emphasized.

Title: Monogènes spécifiques à leur hôte parasitant les poissons d'eau douce : écologie et évolution des associations hôtes-parasites. Abstract: Les Monogènes (Plathelminthes), principalement ectoparasites des branchies et des nageoires des poissons, sont souvent reconnus comme spécifiques à leur hôte et diversifiés morphologiquement et écologiquement. Ces parasites présentent une grande diversité d'espèces au niveau des espèces hôtes ou des spécimens individuels de poissons. À l'aide d'études de cas (en particulier celles largement réalisées chez les Dactylogyrus parasitant les poissons cyprinoïdes), les connaissances actuelles sur l'écologie et l'évolution des monogènes branchiaux congénères sont présentées. Les aspects importants de l'écologie des monogènes congénères sont mis en évidence, en particulier la spécificité à l'hôte exprimée à plusieurs niveaux de l'hôte (de la spécificité stricte à la spécificité phylogénétique), la spécificité du microhabitat exprimée par des positions restreintes sur les branchies des poissons pour faciliter l'accouplement intraspécifique, et le lien entre la préférence du microhabitat et l'adaptation morphologique (c'est-à-dire les structures sclérifiées du hapteur) ou l'isolement reproductif. Du point de vue évolutif, l'étude a été concentrée sur les processus de spéciation et de diversification des monogènes congénères, soulignant le rôle du changement d'hôte comme l'événement coévolutif le plus important, accompagné surtout dans certains cas de spéciation ou de cospéciation intra-hôte, comme le révèlent les études cophylogénétiques. Des connaissances importantes sont présentées ici sur les modèles évolutifs de spécificité d'hôte, de spécificité de microhabitat et d'adaptation morphologique. Les monogènes spécifiques à l'hôte peuvent représenter un outil important pour étudier la biogéographie historique de leurs hôtes. Plus précisément, dans le cas des poissons d'eau douce hôtes présentant une distribution disjonctive, ils reflètent à la fois des contacts historiques et contemporains. Le rôle des monogènes congénères spécifiques à leur hôte dans la révélation des contacts intercontinentaux et intracontinentaux historiques entre poissons d'eau douce est mis en évidence. Enfin, l'importance du rôle de la coadaptation génétique limitant la présence de monogènes spécifiques à l'hôte chez les poissons hybrides est soulignée.

Pemphigus Vulgaris Unmasked in a Patient With Behçet's Disease: A Complex Diagnostic Dilemma.

Behçet's disease (BD) is a systemic vasculitis characterized by recurrent painful oral and genital ulcers, uveitis, and skin lesions. Pemphigus vulgaris (PV), on the other hand, is an autoimmune blistering disorder affecting the mucous membranes and skin, characterized by the presence of intraepidermal vesicles. Herein, we present a female in her 40s with a history of BD who presented to the emergency department with worsening oral and vaginal ulcers and extensive bullae of four months onset. A skin biopsy revealed an intraepidermal vesicle with preservation of the basal layer consistent with PV. A complete workup including vasculitides, connective tissue diseases, and human leukocyte antigen (HLA)-B*51 was performed, which revealed a positive HLA-B*51. She was treated with oral corticosteroids, rituximab, dapsone, and azathioprine. After nine months, she has remained stable. Our case suggests there may be a shared pathway in the pathophysiology of BD and PV, providing valuable insights for treatment decisions.

Why ecologists struggle to predict coexistence from functional traits.

The rationale behind trait-based ecology is that shifting focus from species' taxonomic names to their measurable characteristics ('functional traits') leads to greater generality and predictive power. This idea has been applied to one of ecology's most intractable problems: the coexistence of competing species. But after 20 years, we lack clear evidence that functional traits effectively predict coexistence. Here, we present a theory-based argument for why this might be the case. Specifically, we argue that coexistence often depends on special quantities called 'process-informed metrics' (PIMs), which combine multiple traits and demographic characteristics in non-intuitive ways, obscuring any direct ties between individual traits and coexistence. We then lay a path forward for trait-based coexistence research that builds on mechanistic models of competition.

Predicting and Prioritising Community Assembly: Learning Outcomes via Experiments.

Community assembly provides the foundation for applications in biodiversity conservation, climate change, invasion, restoration and synthetic ecology. However, predicting and prioritising assembly outcomes remains difficult. We address this challenge via a mechanism-free approach useful when little data or knowledge exist (LOVE; Learning Outcomes Via Experiments). We carry out assembly experiments ('actions', here, random combinations of species additions) potentially in multiple environments, wait, and measure abundance outcomes. We then train a model to predict outcomes of novel actions or prioritise actions that would yield the most desirable outcomes. Across 10 single- and multi-environment datasets, when trained on 89 randomly selected actions, LOVE predicts outcomes with 0.5%-3.4% mean error, and prioritises actions for maximising richness, maximising abundance, or removing unwanted species, with 94%-99% mean true positive rate and 10%-84% mean true negative rate across tasks. LOVE complements existing mechanism-first approaches for community ecology and may help address numerous applied challenges.

Variation in season length and development time is sufficient to drive the emergence and coexistence of social and solitary behavioural strategies.

Season length and its associated variables can influence the expression of social behaviours, including the occurrence of eusociality in insects. Eusociality can vary widely across environmental gradients, both within and between different species. Numerous theoretical models have been developed to examine the life history traits that underlie the emergence and maintenance of eusociality, yet the impact of seasonality on this process is largely uncharacterized. Here, we present a theoretical model that incorporates season length and offspring development time into a single, individual-focused model to examine how these factors can shape the costs and benefits of social living. We find that longer season lengths and faster brood development times are sufficient to favour the emergence and maintenance of a social strategy, while shorter seasons favour a solitary one. We also identify a range of season lengths where social and solitary strategies can coexist. Moreover, our theoretical predictions are well matched to the natural history and behaviour of two flexibly eusocial bee species, suggesting that our model can make realistic predictions about the evolution of different social strategies. Broadly, this work reveals the crucial role that environmental conditions can have in shaping social behaviour and its evolution and it underscores the need for further models that explicitly incorporate such variation to study the evolutionary trajectories of eusociality.

Benign Brenner Tumor Mixed with Mucinous Cystadenoma of the Left Ovary: Case Report and Literature Review, 2023.

Ovarian mucinous tumors mixed with Brenner tumors have rarely been reported. The coexistence of such epithelial tumors present histopathologic diagnostic difficulties. Here we report a 57-year-old postmenopausal woman who had experienced an abdominal distention and pain over a period of eight months. A physical examination revealed a grossly distended abdomen that reached the xiphoid process. A firm and mobile abdomino-pelvic mass with a smooth surface and a regular border was identified. Laboratory investigations showed a hemoglobin level of 13.54 g/dl and a serum cancer antigen 125 (CA125) of 97.3 U/mL. Trans abdominal ultrasonography revealed a massive complex mass originating from the left adnexa. A laparotomy was performed and a 10 kg left adnexal mass was removed intact. Histopathological analysis revealed mixed benign mucinous cystadenoma with a Brenner tumor of the left ovary. After surgery the patient showed marked clinical improvement, resumed her regular daily activities in three months and no recurrence has occurred during her long follow up. As the coexistence of these mixed tumors is not uncommon, a thorough pathologic evaluation is necessary and health professionals should be aware of the mixed occurrence of epithelial ovarian tumors.

Identifying Priority Areas for the Indian Leopard (Panthera pardus fusca) Within a Shared Landscape.

Habitat loss is one of the primary drivers of large felid decline. The leopard (Panthera pardus), a generalist large felid species, has the behavioural and dietary flexibility to exploit different habitat types of varying human influence. Understanding habitat selection in a shared landscape is critical for the development of conservation strategies and managing negative human-leopard interactions. The development of conservation policy requires data on large spatial scales, which is mostly lacking, especially within shared landscapes in India. This study aims to determine habitat selection by Indian leopards and the anthropogenic, environmental, and climatic variables contributing to this selection. Leopard occurrence records were obtained from an occupancy survey conducted in the five administrative districts in Karnataka (28,375 km2). 267 randomly selected 30 km2 grids were each walked for 10 km and all leopard signs were recorded. Environment variables were chosen to reflect land use, climatic, topographic, and human disturbances that could affect habitat selection at a resolution of 0.1 km2. The mean ensemble model was projected to the state of Karnataka. Habitat selection predicted by the ensemble model was driven by proximity to forest cover and rocky outcrops, higher precipitation, and negatively by distance to cropland and roads. Protected Areas and Reserved Forests in the study covered 47% of the predicted habitat, while 25% is within human-use areas such as human habitation and croplands. This study predicts that half of the habitat selected by leopards is outside of protected areas and reserved forests. The selection of human-use areas is predicted because of the availability of cover from irrigated croplands and the proximity to natural cover that provides refuge. Livestock density did not drive large-scale habitat selection. The preservation of natural cover and rocky outcrops that provide refuge between protected areas is paramount for leopard conservation.

It's about (taking up) space: Discreteness of individuals and the strength of spatial coexistence mechanisms.

One strand of modern coexistence theory (MCT) partitions invader growth rates (IGR) to quantify how different mechanisms contribute to species coexistence, highlighting fluctuation-dependent mechanisms. A general conclusion from the classical analytic MCT theory is that coexistence mechanisms relying on temporal variation (such as the temporal storage effect) are generally less effective at promoting coexistence than mechanisms relying on spatial or spatiotemporal variation (primarily growth-density covariance). However, the analytic theory assumes continuous population density, and IGRs are calculated for infinitesimally rare invaders that have infinite time to find their preferred habitat and regrow, without ever experiencing intraspecific competition. Here we ask if the disparity between spatial and temporal mechanisms persists when individuals are, instead, discrete and occupy finite amounts of space. We present a simulation-based approach to quantifying IGRs in this situation, building on our previous approach for spatially non-varying habitats. As expected, we found that spatial mechanisms are weakened; unexpectedly, the contribution to IGR from growth-density covariance could even become negative, opposing coexistence. We also found shifts in which demographic parameters had the largest effect on the strength of spatial coexistence mechanisms. Our substantive conclusions are statements about one model, across parameter ranges that we subjectively considered realistic. Using the methods developed here, effects of individual discreteness should be explored theoretically across a broader range of conditions, and in models parameterized from empirical data on real communities.

Trade-offs between receptor modification and fitness drive host-bacteriophage co-evolution leading to phage extinction or co-existence.

Parasite-host co-evolution results in population extinction or co-existence, yet the factors driving these distinct outcomes remain elusive. In this study, Salmonella strains were individually co-evolved with the lytic phage SF1 for 30 days, resulting in phage extinction or co-existence. We conducted a systematic investigation into the phenotypic and genetic dynamics of evolved host cells and phages to elucidate the evolutionary mechanisms. Throughout co-evolution, host cells displayed diverse phage resistance patterns: sensitivity, partial resistance, and complete resistance, to wild-type phage. Moreover, phage resistance strength showed a robust linear correlation with phage adsorption, suggesting that surface modification-mediated phage attachment predominates as the resistance mechanism in evolved bacterial populations. Additionally, bacterial isolates eliminating phages exhibited higher mutation rates and lower fitness costs in developing resistance compared to those leading to co-existence. Phage resistance genes were classified into two categories: key mutations, characterized by nonsense/frameshift mutations in rfaH-regulated rfb genes, leading to the removal of the receptor O-antigen; and secondary mutations, which involve less critical modifications, such as fimbrial synthesis and tRNA modification. The accumulation of secondary mutations resulted in partial and complete resistance, which could be overcome by evolved phages, whereas key mutations conferred undefeatable complete resistance by deleting receptors. In conclusion, higher key mutation frequencies with lower fitness costs promised strong resistance and eventual phage extinction, whereas deficiencies in fitness cost, mutation rate, and key mutation led to co-existence. Our findings reveal the distinct population dynamics and evolutionary trade-offs of phage resistance during co-evolution, thereby deepening our understanding of microbial interactions.