关键词： Agricultural regimes   Dryland agriculture   Invasive predators   Land-use   Predator-prey interactions   Socio-ecological systems   Species distributions   Trophic cascades   Vegetation change  

摘要： Dryland agriculture has extensive impacts on surrounding ecosystems through its unintentional provision of food and water resources to local wildlife. We analyzed the response of a predator community of jackals, wolves and foxes to land-management choices, and how that response in turn affects native gazelles and Acacia vegetation in the Arava Valley of Israel. This hyperarid region is characterized by contrasting regimes comprising privatized (Moshavim) and communal (Kibbutzim) agricultural settlements, which provides ideal conditions for evaluating how land-management differences translate into crop choices, affecting resource availability and ecosystem changes. Integrating multi-year field observations of predators and gazelles with agricultural datasets, we show that shifts in land-use strategies have cascading ecological impacts. This is evident in the association of date orchards, an expanding land use especially in Kibbutzim, with shifts in the geographical and seasonal distributions of predators. Increased predator presence due to resource availability has displaced gazelles farther from settlements, subsequently impacting Acacia seed dispersal and recruitment. Considering the global expansion of dryland agriculture, the evidence of such socio-ecological cascading effects suggests the necessity to approach agricultural management at the landscape scale in desert regions.

关键词： bile canaliculi   bile ducts   biliary mucous glands   biliary tree   structural modules  

摘要： The study of the fractal architecture of various organs and structures expanded the possibilities for determining the ranges of their functioning and structural arrangement, which, as a result, was reflected in the development of new approaches to diagnostics and therapeutic impacts. The architecture of the excretory duct systems, similar to the hemo- and lymph- circulatory beds and the bronchial tree, is considered fractal. At the same time, information about hitherto unknown structures of the biliary tree continues to appear in the literature. We aimed to study the features of the spatial geometry of the biliary tree and assess the significance of both its fractal and Euclidean characteristics for the development of approaches that facilitate comprehensive description of intrahepatic biliary tract architecture. We investigated the architecture of the biliary trees of six men, seven male canines, and seven male Wistar rats using the corrosion casting method. Corrosion casts were prepared by injecting solidifying latexes into the bile ducts. The preparations were studied using a light stereomicroscope and a scanning electron microscope. Biliary tree branching is of various types. In addition, the correlation between variations in the caliber and length of the bile ducts and their order is not significant. Therefore, the biliary tree should not be considered as a classical fractal and it consists of the main modules, represented by the network of the bile canaliculi (first nonfractal module) and a biliary tree with a fractal branching (second module) that drains the bile canaliculi mesh and the additional modules represented by the mucosal biliary glands (in mammals with the gallbladder) or the periportal biliary plexus (in mammals without a gallbladder) and the aberrant biliary ducts. Such a configuration of the biliary bed should optimally ensure the smooth implementation of the physiological function of the liver, as well as its adaptation to different pathologies

关键词： Miombo woodland   Agriculture expansion   Fragmentation   alpha-and beta-diversity   Occupancy   Mozambique  

摘要： Land use change (LUC) is the leading cause of biodiversity loss worldwide. However, the global understanding of LUC's impact on biodiversity is mainly based on comparisons of land use endpoints (habitat vs non-habitat) in forest ecosystems. Hence, it may not generalise to savannas, which are ecologically distinct from forests, as they are inherently patchy, and disturbance adapted. Endpoint comparisons also cannot inform the management of intermediate mosaic landscapes. We aim to address these gaps by investigating species-and community-level responses of mammals and trees along a gradient of small scale agricultural expansion in the miombo woodlands of northern Mozambique. Thus, the case study represents the most common pathway of LUC and biodiversity change in the world's largest savanna. Tree abundance, mammal occupancy, and tree- and mammal-species richness showed a non-linear relationship with agricultural expansion (characterised by the Land Division Index, LDI). These occurrence and diversity metrics increased at intermediate LDI (0.3 to 0.7), started decreasing beyond LDI> 0.7, and underwent high levels of decline at extreme levels of agricultural expansion (LDI> 0.9). Despite similarities in species richness responses, the two taxonomic groups showed contrasting beta-diversity patterns in response to increasing LDI: increased dissimilarity among tree communities (heterogenisation) and high similarity among mammals (homogenisation). Our analysis along a gradient of landscape-scale land use intensification allows a novel understanding of the impacts of different levels of land conversion, which can help guide land use and restoration policy. Biodiversity loss in this miombo landscape was lower than would be inferred from existing global syntheses of biodiversity-land use relations for Africa or the tropics, probably because such syntheses take a fully converted landscape as the endpoint. As, currently, most African savanna landscapes are a mosaic of savanna h

关键词： Frog   Transcriptome   Peptide   Anntoxin   Predator  

摘要： Gene-encoded peptides with distinct potent bioactivities enable several animals to take advantage of fierce interspecific interaction, as seen in the skin secretion of amphibians. Unlike, most amphibian species that frequently switches terrestrial-aquatic habitats and hides easily from terrestrial predators, tree frogs of small body size are considered as the vulnerable prey in the arboreal habitat. Here, we show the structural and functional diversity of peptide families based on the skin transcriptome of Hyla japonica, which has evolved to be wrapped as an efficient chemical toolkit for defensive use in arboreal habitat. Generally, the presence of antimicrobial peptide and proteinase inhibitor families reveals the functional consistency of Hyla japonica skin compared to other amphibian species. Furthermore, we found that Anntoxin-like neurotoxins with high expression levels are species-specific in tree frogs. Interestingly, derivatives in the Anntoxin-like family exhibit multiple evolutionary traits in modifying the copy number, folding type, and three-dimensional architecture, which are considered essential for targeting the ion channels of terrestrial predators. Together, our study not only reveals the peptide diversity in the skin secretion of H. japonica, but also draws insights into the predator-deterring strategy for coping with arboreal habitat.

关键词： Nothofagus forests   Cavity-bearing trees   Cavity-using wildlife   Multi-model inference   Wildlife conservation  

摘要： Maintenance of tree cavity supply is a global conservation priority for forest wildlife, which requires understanding the ecology and population dynamics of cavity-bearing trees. Explaining the occurrence of cavities in trees is particularly important in ecosystems where most secondary cavity-users (SCUs) are critically dependent on the slow formation of cavities by wood-decay processes. Our main objectives were (1) to explain the distribution of decay cavities in trees according to their individual attributes and, (2) to quantify the relative importance of each individual tree attribute to determine the presence of decay cavities. We focused on medium and large decay cavities (smallest entrance dimension >= 5 cm), which can limit populations of managementsensitive SCUs. We measured forest attributes and inspected cavities in trees (n = 860) and snags (n = 93) in six 0.5 ha plots from old- and second-growth Nothofagus dombeyi forest stands. We used generalised linear mixedeffects models (GLMM) to analyse the distribution of decay cavities in trees using data on their presence/absence, based on several tree individual attributes, across different sites. We applied an information-theoretical and multi-model inference approach to quantify the strength of alternative sets of hypotheses/models. We used model averaging, which allows estimating coefficients and making inferences that account for model and parameter uncertainty. Diameter at breast height (DBH), crown damage and decay, crown ratio (crown length center dot trunk length-1) and woodpecker foraging signs were important to explain the presence/absence of decay cavities in trees. Diameter at breast height, woodpecker foraging signs and a moderate-high crown damage and decay were positively related with decay cavity presence. The presence of medium and large decay cavities was also positively related with DBH, but trees with low crown ratios had relatively low probabilities of presenting these cavities, even with D

关键词： browser   exclusion experiment   grazer   mixed feeder   plant-herbivore interactions   savanna   top-down  

摘要： 1. Herbivory is a key process structuring vegetation in savannas, especially in Africa where large mammal herbivore communities remain intact. Exclusion experiments consistently show that herbivores impact savanna vegetation, but effect size variation has resisted explanation, limiting our understanding of the past, present and future roles of herbivory in savanna ecosystems. 2. Synthesis of vegetation responses to herbivore exclusion shows that herbivory decreased grass abundance by 57.0% and tree abundance by 30.6% across African savannas. 3. The magnitude of herbivore exclusion effects scaled with herbivore abundance: more grazing herbivores resulted in larger grass responses and more browsing herbivores in larger tree responses. However, existing experiments are concentrated in semi-arid savannas (400-800-mm rainfall) and soils data are mostly lacking, which makes disentangling environmental constraints a challenge and priority for future research. 4. Observed herbivore impacts were similar to 2.1x larger than existing estimates modelled based on consumption. Wildlife metabolic rates may be higher than are usually used for estimating consumption, which offers one clear avenue for reconciling estimated herbivore consumption with observed herbivore impacts. Plant-soil feedbacks, plant community composition, and the phenological or demographic timing of herbivory may also influence vegetation productivity, thereby magnifying herbivore impacts. 5. Because herbivore abundance so closely predicts vegetation impact, changes in herbivore abundance through time are likely predictive of the past and future of their impacts. Grazer diversity in Africa has declined from its peak 1 million years ago and wild grazer abundance has declined historically, suggesting that grazing likely had larger impacts in the past than it does today. 6. Current wildlife impacts are dominated by small-bodied mixed feeders, which will likely continue into the future, but the magnitude of top-dow

关键词： beta diversity   Cerrado   connectivity   generalized dissimilarity modelling   herpetofauna   regionalization  

摘要： Aim Cross-taxonomic congruence in biodiversity patterns is key to understanding the main drivers of community structure, for biogeographical regionalization and to guide conservation. We aim to map the patterns of phylogenetic turnover and disentangle the geographical and environmental factors that drive the phylogenetic composition of distinct faunal assemblages. Location The Cerrado savannas of South America. Taxa Reptiles and amphibians. Methods We measured the proportion of phylogenetic branches shared among sites (i.e. phylogenetic turnover) using presence-absence matrices for all species in the Cerrado and for endemics only, including only well-sampled localities from previously compiled inventories. We then tested whether phylogenetic turnover is different from null expectations based on taxonomic turnover. We used generalized dissimilarity modelling (GDM) to test whether geography, topography, soil or climate best explain phylogenetic turnover. Finally, we mapped the observed and the GDM-predicted clustering of phylogenetic turnover to assess geographical congruence between reptiles and amphibians. Results For all reptiles, geographical distance is the most important factor explaining phylogenetic turnover, whereas for endemic reptiles and amphibians, in general, a set of climatic variables and relief roughness are more important. We did not find any significant correlation between the phylogenetic turnover of reptiles and amphibians, as evidenced by non-congruent phylogenetic clustering and by different responses to geographical and environmental gradients. Main conclusions The different relationships of phylogenetic turnover of reptiles and amphibians to geographical and environmental distances have ultimately shaped the phylogenetic regionalization of these two groups. This incongruence indicates the differential importance of niche filtering, dispersal limitation and the influence of neighbouring biomes in the regionalization of different groups of organ

关键词： Conservation status   Felidae   Grasslands   Neotropics   Species distribution models  

摘要： Mun tilde oa's pampas cat (recently proposed to be a distinct species, Leopardus munoai) is a small felid that is endemic to the Uruguayan Savanna ecoregion (encompassing southern Brazil, north-eastern Argentina and Uruguay). Previous studies have suggested that it is threatened, but its conservation assessment has been hampered by the scarcity of data on its ecology, including spatial distribution, population size, and connectivity. To address these issues, we developed current spatial distribution models and used them to: (i) identify the environmental variables affecting L. munoai habitat suitability;(ii) generate estimates of population size to assess its conservation status based on IUCN criteria;(iii) estimate habitat suitability in protected areas;(iv) identify potential paths of connectivity among protected areas and sites of confirmed occurrence;and (v) assess the proportion of the estimated connectivity paths that overlap with threatened areas (based on future threat projections). Our results indicated higher habitat suitability in the central area of the species' distribution. All estimates (based on different demographic assumptions) indicated that L. munoai should be categorized in one of the IUCN threatened categories. Worryingly, several estimates indicated that it may be Critically Endangered. Only 0.73 % of its high-suitability landscape is presently protected, and connectivity among most protected areas and occurrence records was low. Additionally, areas with estimated connectivity among occurrence records mostly overlapped with regions with a high level of future habitat loss threat (92.46 %), highlighting the urgent need for an international approach to ensure the long-term survival of this elusive felid.

关键词： indirect effects   megafauna   pollination   species interactions   trophic cascade   ungulate  

摘要： Pollination by animals is a key ecosystem service(1,2) and interactions between plants and their pollinators are a model system for studying ecological networks,(3,4) yet plant-pollinator networks are typically studied in isolation from the broader ecosystems in which they are embedded. The plants visited by pollinators also interact with other consumer guilds that eat stems, leaves, fruits, or seeds. One such guild, largemammalian herbivores, are well-known ecosystem engineers(5-7) and may have substantial impacts on plant-pollinator networks. Although moderate herbivory can sometimes promote plant diversity,(8) potentially benefiting pollinators, large herbivores might alternatively reduce resource availability for pollinators by consuming flowers,(9) reducing plant density,(10) and promoting somatic regrowth over reproduction.(11) The direction and magnitude of such effects may hinge on abiotic context-in particular, rainfall, which modulates the effects of ungulates on vegetation.(12) Using a long-term, large-scale experiment replicated across a rainfall gradient in central Kenya, we show that a diverse assemblage of native large herbivores, ranging from 5kg antelopes to 4,000-kg African elephants, limited resource availability for pollinators by reducing flower abundance and diversity;this in turn resulted in fewer pollinator visits and lower pollinator diversity. Exclusion of large herbivores increased floral-resource abundance and pollinator-assemblage diversity, rendering plant-pollinator networks larger, more functionally redundant, and less vulnerable to pollinator extinction. Our results show that species extrinsic to plant-pollinator interactions can indirectly and strongly alter network structure. Forecasting the effects of environmental change on pollination services and interaction webs more broadly will require accounting for the effects of extrinsic keystone species.

关键词： ants   drought   grasshoppers   rainfall   savanna   termite mounds  

摘要： Global climate change is predicted to increase the frequency of droughts, with major impacts on tropical savannas. It has been suggested that during drought, increased soil moisture and nutrients on termite mounds could benefit plants but it is unclear how such benefits could cascade to affect insect communities. Here, we describe the effects of drought on vegetation structure, the cascading implications for invertebrates and how termite mounds influence such effects. We compared how changes in grass biomass affected grasshopper and ant diversity on and off Macrotermes mounds before (2012) and during a drought (2016) at two locations that experienced large variation in drought severity (Skukuza and Pretoriuskop) in the Kruger National Park, South Africa. The 2013-2016 drought was not ubiquitous across the study site, with rainfall decreasing at Skukuza and being above average at Pretoriuskop. However, grass biomass declined at both locations. Grasshopper abundance decreased at droughted Skukuza both on and off mounds but decreased on mounds and increased off mounds at non-droughted Pretoriuskop. Ant abundance and species richness increased at Skukuza but remained the same on mounds and decreased off mounds at Pretoriuskop. Our results demonstrate the spatially extensive effects of drought. Despite above average rainfall in 2016 at Pretoriuskop, grass biomass decreased, likely due to an influx of large mammalian herbivores from drought-affected areas. This decrease in grass biomass cascaded to affect grasshoppers and ants, further illustrating the effects of drought on invertebrates in adjoining areas with higher rainfall. Our grasshopper results also suggest that increased drought in savannas will contribute to overall declines in insect abundance. Moreover, our recorded increase in ant abundance was primarily in the form of increases in dominant species, illustrating how drought-induced shifts in relative abundance will likely influence ecosystem structure and func