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Context: Distribution and abundance of the three northern Australian tree-rat species, Conilurus penicillatus , Mesembriomys macrurus and M. gouldii , have contracted significantly since European settlement. All three species were recorded from the Mitchell Plateau, Western Australia, in the 1980s, enabling their niche separation to be assessed. Despite this study being conducted in 1987, the results remain relevant for conservation strategies for these species. Aims: To determine the ecological separation among three tropical tree-rat species by documenting habitat preferences, habitat use and diet. Methods: Live-trapping, radiotracking and spotlighting were used to assess relative abundance, habitat preference and movements of each species at nine sites on the Mitchell Plateau. Diet was determined using scat analysis; vegetation communities were described and characterised by pattern analysis. Key results: C. penicillatus (number of individuals trapped (n) = 24) was most abundant, followed by M. macrurus (n = 8) and M. gouldii (n = 2). Mature open forest with a well-developed understorey was preferred by the predominantly arboreal M. gouldii (1 site), M. macrurus occupied more varied habitats (four sites), especially ecotones between vine thicket and open eucalypt forest and the boulder edges of the plateau, and C. penicillatus occupied the greatest variety of habitats (four sites) in open eucalypt woodland with a diverse shrub layer and ground cover almost absent to very dense, tall grass. Diet analysis identified M. gouldii as a frugivore (fruits, some flowers), M. macrurus as an omnivore (seeds, fruits, flowers, termites, other invertebrates), and C. penicillatus as a generalist (monocot and dicot leaves, seeds, flowers, fruits, some arthropods). Conclusions: The largest of the species, M. gouldii , appeared to have the narrowest ecological niche, preferring more stable, structurally diverse, mature open forest that is infrequently burnt. The mid-sized M. macrurus occupies a broader range of habitats, particularly ecotones between vine thickets and eucalypt forest/woodland and woodland. C. penicillatus preferred open eucalypt woodland with a variable understorey. Implications: With a changing climate, increased fire frequency, habitat degradation by introduced herbivores and predation by cats across the tropical savanna distribution of these threatened tree-rats, this study provides data to underpin actions that may ensure their survival. The distribution and abundance of the three tropical tree-rat species have contracted since European settlement and characterisation of their ecological niche is critical for their conservation. The habitat preferences, habitat use and diet of each species on the Mitchell Plateau, Western Australia, were determined and compared. Despite overlap in habitat and diet preferences, each species is filling a distinct niche. Photograph by Euan Ritchie. [ABSTRACT FROM AUTHOR]

In 2016, IODP‐ICDP Expedition 364 recovered an 829‐meter‐long core within the peak ring of the Chicxulub impact crater (Yucatán, Mexico), allowing us to investigate the post‐impact recovery of the heat‐sterilized deep continental microbial biosphere at the impact site. We recently reported increased cell biomass in the impact suevite, which was deposited within the first few hours of the Cenozoic, and that the overall microbial communities differed significantly between the suevite and the other main core lithologies (i.e., the granitic basement and the overlying Early Eocene marine sediments; Cockell et al., 2021). However, only seven rock intervals were previously analyzed from the geologically heterogenic and impact‐deformed 587‐m‐long granitic core section below the suevite interval. Here, we used 16S rRNA gene profiling to study the microbial community composition in 45 intervals including (a) 31 impact‐shocked granites, (b) 7 non‐granitic rocks (i.e., consisting of suevite and impact melt rocks intercalated into the granites during crater formation and strongly serpentinized pre‐impact sub‐volcanic, ultramafic basanite/dolerite), and (c) 7 cross‐cut mineral veins of anhydride and silica. Most recovered microbial taxa resemble those found in hydrothermal systems. Spearman correlation analysis confirmed that the borehole temperature, which gradually increased from 47 to 69°C with core depth, significantly shaped a subset of the vertically stratified modern microbial community composition in the granitic basement rocks. However, bacterial communities differed significantly between the impoverished shattered granites and nutrient‐enriched non‐granite rocks, even though both lithologies were at similar depths and temperatures. Furthermore, Spearman analysis revealed a strong correlation between the microbial communities and bioavailable chemical compounds and suggests the presence of chemolithoautotrophs, which most likely still play an active role in metal and sulfur cycling. These results indicate that post‐impact microbial niche separation has also occurred in the granitic basement lithologies, as previously shown for the newly formed lithologies. Moreover, our data suggest that the impact‐induced geochemical boundaries continue to shape the modern‐day deep biosphere in the granitic basement underlying the Chicxulub crater. [ABSTRACT FROM AUTHOR]

The diversity of micro-habitats in tropical wetlands allows the coexistence of several species. These sympatric species interact with each other, either directly or indirectly, to optimally use the available resources. They achieve this through niche separation or minimal overlap to avoid competition. India's wetland ecosystems are home to various sympatric species, such as the Great Egret Ardea alba (GE), Median Egret Ardea intermedia (IE), Little Egret Egretta garzetta (LE) and Cattle Egret Bubulcus ibis (CE). These egret species are closely related, and as a result, have similar niche requirements, which could lead to high intra-specific competition. However, there have been few studies on how these species utilize resources. This study aims to understand the possible mechanisms that enable the coexistence of these species in a tropical wetland. We have examined habitat characteristics, feeding behaviour, timings of seasonal and daily activities, and spacing patterns to evaluate possible models of species coexistence. We discovered that these four sympatric egret species have differences in microhabitat selection, activity patterns, both daily and seasonally, and feeding preferences. The study further indicates that there is a relationship between the niche dimensions, but it is only partially dependent on each other. [ABSTRACT FROM AUTHOR]

The survival of butterfly populations depends on successful oviposition strategies. The limited mobility of early life stages requires females to select sites that reflect larval requirements. However, as land use and climate changes are altering habitat conditions and micro-climate, some species may adapt ovipositing strategies and flourish while others, with narrow niche requirements, may be unable to respond. Oviposition site selection and micro-habitat niche is examined for two closely related butterfly species—the specialist High Brown Fritillary (Fabriciana adippe) and relative generalist Dark Green Fritillary (Speyeria aglaja) through field observations of egg-laying females and analysis of micro-habitat characteristics. A total of 104 oviposition behaviour observations across both species were recorded in 69 1 m2 quadrats, with the habitat characteristics compared to randomly selected quadrats in the same area. Results show that higher host plant density was a positively significant factor for oviposition site selection only for the High Brown Fritillary. Moreover, the cover of live Bracken (Pteridium aquilinum) and grass were important for site selection in both species, with High Brown Fritillaries tolerating less live Bracken and grass cover than Dark Green Fritillaries. This confirms the more specific requirements and narrower micro-habitat niche of the High Brown Fritillary, which appears to be more sensitive to micro-habitat cooling. Implications for insect conservation: The management of Bracken mosaic habitats for these two species should aim to supress grass growth and maintain Bracken density within limits, by opening the Bracken canopy on a rotation through grazing or manual cutting, ensuring a continuous supply of suitable micro-habitat. [ABSTRACT FROM AUTHOR]

Climate change has altered precipitation regimes with concomitant influences in hydrology. For a complex assemblage of ungulates, these water-level fluctuations might alter habitat partitioning thought to be crucial for coexistence in response to livestock introduction. We placed camera traps in three habitat types along the Mayanja River in central Uganda to evaluate space use by native and domestic ungulates. For each species, we assessed the difference in the proportion of days with camera-trap detections during three water-level conditions (low in 2017, normal in 2015, and high in 2016). Sitatunga was the only species regularly using wetlands; their use of remote wetlands remained consistent regardless of water-level conditions, and their use of forest habitats decreased during the study. In the forest, warthogs showed no change in use, while proportion of days with detections increased over time for all other ungulates. Our results indicate that ungulate community space use appears to be independent of hydrologic condition, and that risk for competitive exclusion between native and domestic ungulates is tempered by dietary and habitat use differences. Adaptations to dynamic hydrology appears to buffer consequences for ungulate communities; more serious are habitat losses to agriculture and development. [ABSTRACT FROM AUTHOR]

Crocosphaera and Cyanothece are both unicellular, nitrogen-fixing cyanobacteria that prefer different environments. Whereas Crocosphaera mainly lives in nutrient-deplete, open oceans, Cyanothece is more common in coastal, nutrient-rich regions. Despite their physiological similarities, the factors separating their niches remain elusive. Here we performed physiological experiments on clone cultures and expand upon a simple ecological model to show that their different niches can be sufficiently explained by the observed differences in their photosynthetic capacities and rates of carbon (C) consumption. Our experiments revealed that Cyanothece has overall higher photosynthesis and respiration rates than Crocosphaera. A simple growth model of these microorganisms suggests that C storage and consumption are previously under-appreciated factors when evaluating the occupation of niches by different marine nitrogen fixers.

Questions: Soil resource heterogeneity influences the outcome of plant–plant interactions and, consequently, species co‐existence and diversity patterns. The magnitude and direction of heterogeneity effects vary widely, and the processes underlying such variations are not fully understood. In this study, we explored how and under what resource conditions small‐scale heterogeneity modulates grassland plant diversity. Location: Oderhänge Mallnow, Potsdam, Brandenburg, Germany. Methods: We expanded the individual‐based plant community model (IBC‐grass) to incorporate dynamic below‐ground resource maps, simulating spatial heterogeneity of resource availability. Empirical centimeter‐scale data of soil C/N ratio were integrated into the model, accounting for both configurational and compositional heterogeneity. We then analyzed the interplay between small‐scale heterogeneity and resource availability on the interaction and co‐existence of plant species and overall diversity. Results: Our results showed significant differences between the low‐ and high‐resource scenarios, with both configurational and compositional heterogeneity having a positive effect on species richness and Simpson's diversity, but only under low‐resource conditions. As compositional heterogeneity in the fine‐scale C/N ratio increased, we observed a positive shift in Simpson's diversity and species richness, with the highest effects at the highest level of variability tested. We observed little to no effect in nutrient‐rich scenarios, and a shift to negative effects at the intermediate resource level. The study demonstrates that site‐specific resource levels underpin how fine‐scale heterogeneity influences plant diversity and species co‐existence, and partly explains the divergent effects recorded in different empirical studies. Conclusions: This study provides mechanistic insights into the complex relationship between resource heterogeneity and diversity patterns. It highlights the context‐dependent effects of small‐scale heterogeneity, which can be positive under low‐resource, neutral under high‐resource, and negative under intermediate‐resource conditions. These findings provide a foundation for future investigations into small‐scale heterogeneity–diversity relationships, contributing to a deeper understanding of the processes that promote species co‐existence in plant communities. [ABSTRACT FROM AUTHOR]

Simple Summary: Ecologically similar animals can only co-occur if resources are used in a sufficiently diverse manner. The necessary separation can be made according to habitat, food choice and activity pattern. We investigated this question in an inner-alpine mixed forest for bank voles, Clethrionomys glareolus, and mice of the genus Apodemus, the latter being larger and stronger. In the presence of many Apodemus mice, bank voles were indeed more diurnal. We found no alternative explanation for this temporal partitioning, despite considering possible other influencing factors, such as exposure to lunar illumination, temperature, precipitation, the presence of predators or the availability of cover. Our video footage showed that this temporal separation hardly requires any physical interaction between the small forest rodents. We attribute this to the long common evolution of these animals. Sympatric animals with similar requirements can separate their ecological niches along the microhabitat, food and time axes. There may be alternative reasons for an interspecific different activity pattern, such as intraspecific social constraints, predator avoidance or physical conditions such as temperature, precipitation and illumination. We investigated the importance of intraguild competition in a 2-year study in an inner-alpine mixed forest, using small forest rodents as our model species. Apodemus mice were the physically superior, and bank voles, Clethrionomys glareolus, the inferior competitor. We predicted that bank voles would exhibit increased diurnal activity when frequencies of the almost exclusively nocturnal Apodemus mice were high during a seed mast year. To investigate this, we recorded 19,138 1 min videos. Controlling for confounding variables, bank vole diurnal activity was significantly related to the frequency of Apodemus mice. We assume that at high densities of Apodemus mice, a purely nocturnal separation in the niche dimensions of time, habitat and microhabitat is no longer sufficient, and therefore an inverse activity pattern by the bank voles is reinforced. Our videos showed, however, that this does not require persistent aggressive meetings and we explain this by the long co-evolution of the taxa under study. [ABSTRACT FROM AUTHOR]

Legumes, as an important biological nitrogen (N) fixation resource, could effectively supplement N inputs to terrestrial ecosystems, especially in N-poor desert ecosystems. However, there is limited research on the N utilization strategies of different plant life forms coexisting under the "fertilizer island effect" created by leguminous shrubs. The study aims to explore the N acquisition patterns of herbaceous plants adjacent to Eremosparton songoricum (Litv.) Vassilcz. in the Gurbantungut Desert of northern China. In this study, the 15N isotope labeling method was used to track the N acquisition of the companion plants Ceratocarpus arenarius L. and Centaurea pulchella Ledeb. within 0–10 cm (D1), 30–40 cm (D2), 60–70 cm (D3), and 90–100 cm (D4) from a dominant legume species E. songoricum. The results showed that: (1) The "N acquisition" by herbaceous plants near leguminous shrubs showed distinct effects related to distance, with a preference for N-NH 4 + (contribution rate: 25.42 % ∼ 58.94 %) at a closer distance from the shrub, and a preference for N-NO 3 −(contribution rate: 17.17 %–54.65 %) at a farther distance. (2) There was niche separation in the acquisition of organic N by the associated species of different life forms, in which the 15N-Glycine recovery and absorption rate of Cer. arenarius decreased with the increase of distance level (D1 > D2 > D3 > D4). However, Cen. pulchella had the maximum 15N-Glycine recovery at D4 (90–100 cm) (D1 < D2 < D3 < D4). (3) By analyzing the key driving factors that influence the N form preferences of non-leguminous plants associated with leguminous shrubs, it was found that the biomass of the 2 species tended to increase with increasing distance levels, and the preference for N forms changed from ammonium N to nitrate N. However, increased distance had a positive effect on the acquisition of N-Glycine and N-NO 3 −, whereas it negatively impacted the uptake of N-NH 4 +. These findings revealed that in N-poor desert ecosystems, herbaceous plants near leguminous shrubs adjusted their N preferences based on distance to optimize N uptake and facilitate niche coexistence. This study provides data that support a deeper understanding of the mechanisms of species coexistence and ecological stability assessments among diverse plant species in desert environments. [Display omitted] [ABSTRACT FROM AUTHOR]

Over 84% of the river ecosystems in South Africa are threatened and, accordingly freshwater dependent species such as the Cape clawless otter (Aonyx capensis) and the water mongoose (Atilax paludinosus) are also declining in numbers. These species share a similar diet and habitat preference and in certain places in South Africa it is known that they occur in sympatry. Our study focused on a pristine river system in the far western Soutpansberg where little is known about the local distribution and habitat preferences of these species. To determine the distribution and fine scale habitat preferences of otters and water mongooses, tracks and signs (TS) and camera traps were used, and spraint content analysed to establish differences in diet. Based on the TS that were found, the Cape clawless otter and water mongoose are both widely distributed along the river system and mostly occur separate from each other. The observed amount of TS of Cape clawless otters was higher in areas with pools, rocky riverbanks and areas with a stream width of 2 - >5 m in diameter. The number of water mongoose TS recorded was higher in wetland areas with leafy riverbanks and areas with a stream width of up to 2 m. We suggest that Cape clawless otters and water mongooses may avoid direct competition by habitat partitioning in the western Soutpansberg. [ABSTRACT FROM AUTHOR]

There is an increasing emphasis in conservation strategies for large carnivores on facilitating their coexistence with humans. Justification for coexistence strategies should be based on a quantitative assessment of currently remaining large carnivores in human‐dominated landscapes. An essential part of a carnivore's coexistence strategy has to rely on its prey. In this research, we studied snow leopards Panthera uncia whose habitat mainly comprises human‐dominated, unprotected areas, to understand how a large carnivore and its primary prey, the bharal Pseudois nayaur, could coexist with human land use activities in a large proportion of its range. Using a combination of livestock census, camera trapping and wildlife surveys, across a broad gradient of livestock grazing intensity in a 363 000 km2 landscape on the Tibetan Plateau, we found no evidence of livestock grazing impacts on snow leopard habitat use, bharal density and spatial distribution, even though livestock density was 13 times higher than bharal density. Bharal were found to prefer utilizing more rugged habitats at higher elevations with lower grass forage conditions, whereas livestock dominated in flat valleys at lower elevations with higher productivity, especially during the resource‐scarce season. These findings suggest that the spatial niche separation between bharal and livestock, together with snow leopards' specialized bharal diet, minimized conflicts and allowed snow leopards and bharal to coexist in landscapes dominated by livestock grazing. In recent years, reduced hunting and nomadic herder's lifestyle changes towards permanent residence may have further reinforced this spatial separation. Our results indicated that, for developing conservation strategies for large carnivores, the niche of their prey in relation to human land‐use is a key variable that needs to be evaluated. [ABSTRACT FROM AUTHOR]

To explore the daily and seasonal activity patterns of sympatric Elliot's pheasant(Syrmaticus ellioti),silver pheasant(Lophura nycthemera),koklass pheasant(Pucrasia macrolopha)in the Qingliangfeng National Nature Reserve,Zhejiang Province,120 infrared cameras were installed from January 2018 to December 2020.Kernel density estimation and coefficient of overlap analyses showed that:(1)In terms of daily activity rhythms,the three pheasant species are diurnal animals that are most active during the morning and at dusk.Also,while the overlapping coefficient of daily activity rhythm was high,the activity peaks of the three pheasant species did not completely overlap.(2)The daily activity rhythms of the three pheasant species changed from season to season.Niche separation mostly occurred in the morning during spring,autumn,and winter months,whereas the activity peaks of the species were similar in the evening.(3)In summer,the activity periods of all three pheasant species increased relative to the other seasons.During this time,the Elliot's pheasant(05:00—07:00 and 17:00—19:00)and koklass pheasant(05:00—07:00 and 14:00—16:00)maintained bimodal activity peaks in both the morning and evening,whereas the silver pheasant shifted to a single peak pattern(09:00).The overlapping coefficient of daily activity rhythms between different seasons was relatively low compared with the coefficient over the whole year,indicating that annual cumulative data could mask seasonal difference.This study revealed that how these three species consistently separate their temporal niches,suggesting that seasonal differences should be considered in future studies of activity rhythms to help understand the ecological habits of different pheasants,and provided a basis for a seasonal conservation strategy of pheasant populations in the reserve. [ABSTRACT FROM AUTHOR]

Introduction of the domestic cat and red fox has devastated Australian native fauna. We synthesized Australian diet analyses to identify traits of prey species in cat, fox and dingo diets, which prey were more frequent or distinctive to the diet of each predator, and quantified dietary overlap. Nearly half (45%) of all Australian terrestrial mammal, bird and reptile species occurred in the diets of one or more predators. Cat and dingo diets overlapped least (0.64 ± 0.27, n = 24 location/time points) and cat diet changed little over 55 years of study. Cats were more likely to have eaten birds, reptiles and small mammals than foxes or dingoes. Dingo diet remained constant over 53 years and constituted the largest mammal, bird and reptile prey species, including more macropods/potoroids, wombats, monotremes and bandicoots/bilbies than cats or foxes. Fox diet had greater overlap with both cats (0.79 ± 0.20, n = 37) and dingoes (0.73 ± 0.21, n = 42), fewer distinctive items (plant material, possums/gliders) and significant spatial and temporal heterogeneity over 69 years, suggesting the opportunity for prey switching (especially of mammal prey) to mitigate competition. Our study reinforced concerns about mesopredator impacts upon scarce/threatened species and the need to control foxes and cats for fauna conservation. However, extensive dietary overlap and opportunism, as well as low incidence of mesopredators in dingo diets, precluded resolution of the debate about possible dingo suppression of foxes and cats.

Context. The spatio-temporal partitioning of large carnivores is influenced by interspecific competition and coexistence within small, enclosed reserves. Lions (Panthera leo), spotted hyaenas (Crocuta crocuta) and leopards (Panthera pardus) are the three largest African carnivores and have the greatest potential for intra-guild competition, particularly where space is limited. Aim. To investigate the spatio-temporal partitioning between lions, spotted hyaenas and leopards in a small (~75 000 ha), enclosed nature reserve, Madikwe Game Reserve (Madikwe), South Africa. Methods. We deployed 110 camera traps (baited n = 55 and unbaited n = 55) across Madikwe from 26 August 2019 until 6 May 2020. Von Mises kernel density plots were used to investigate daily temporal partitioning among the three species. A multiple-species, singleseason occupancy model was used to investigate daily space use patterns. Key results. We found both temporal and spatial exclusion between lions and spotted hyaenas on Madikwe. However, no evidence was found of spatio-temporal partitioning between lions and leopards, and spotted hyaenas and leopards. Conclusions. Exploitative and interference competition on Madikwe might be high enough to warrant spatio-temporal partitioning between lions and spotted hyaenas to avoid the negative effects of intra-guild competition. Contrastingly, patterns observed between leopards and both lions and spotted hyaenas preclude the possibility of topdown control by superior carnivores. Implication. These findings call for an adaptive management approach, where both carnivore and prey species compositions are constantly monitored. Management strategies such as these will allow for the conservation of valuable resources (i.e. prey species) to ensure the persistence of large carnivore populations across African ecosystems. [ABSTRACT FROM AUTHOR]

The larva of Syssphinx tamaulipasiana (Brechlin and Meister) is described and compared with the three congeners with which it co-occurs in the Lower Rio Grande Valley of Texas: S. albolineata (Grote & Robinson), S. blanchardi (Ferguson), and S. heiligbrodti (Harvey). All four species feed exclusively on mimosid trees, but have nearly non-overlapping host use. We illustrate six instars of S. tamaulipasiana from a lab-reared cohort and wild last instars of all four moths, and offer a key to their last instars. Three of the four species (all but S. heiligbrodti) are restricted to the Lower Rio Grande Valley, where they are threatened by urbanization and insularization. [ABSTRACT FROM AUTHOR]

The light-to-nutrient hypothesis proposes that under high light-to-nutrient conditions, bacteria tend to be limited by phosphorus (P), while under relatively low light-to-nutrient conditions, bacteria are likely driven towards carbon (C) limitation. Exploring whether this light-to-nutrient hypothesis is fitting for alpine lakes has profound implications for predicting the impacts of climatic and environmental changes on the structures and processes of aquatic ecosystems in climate-sensitive regions. We investigated the environmental conditions and bacterioplankton community compositions of 15 high-elevation lakes (7 above and 8 below treeline). High light-to-nutrient conditions (denoted by the reciprocal value of the attenuation coefficient (1/K) to total phosphorus (TP)), high chlorophyll a (Chl a) concentrations, low TP concentrations and low ratios of the dissolved organic carbon concentration to the dissolved total nitrogen concentration (DOC:DTN) were detected in above-treeline lakes. Significant positive correlations between the bacterioplankton community compositions with 1/K:TP ratios and Chl a concentrations indicated that not only high light energy but also nutrient competition between phytoplankton and bacteria could induce P limitation for bacteria. In contrast, low light-to-nutrient conditions and high allochthonous DOC input in below-treeline lakes lessen P limitation and C limitation. The most abundant genus, Polynucleobacter, was significantly enriched, and more diverse oligotypes of Polynucleobacter operational taxonomic units were identified in the below-treeline lakes, indicating the divergence of niche adaptations among Polynucleobacter oligotypes. The discrepancies in the light-to-P ratio and the components of organic matter between the above-treeline and below-treeline lakes have important implications for the nutrient limitation of bacterioplankton and their community compositions. [ABSTRACT FROM AUTHOR]

The cyanobacterium Trichodesmium plays an essential role supporting ocean productivity by relieving nitrogen limitation via dinitrogen (N2) fixation. The two common Trichodesmium clades, T. erythraeum and T. thiebautii, are both observed in waters along the West Florida Shelf (WFS). We hypothesized that these taxa occupy distinct realized niches, where T. thiebautii is the more oceanic clade. Samples for DNA and water chemistry analyses were collected on three separate WFS expeditions (2015, 2018, and 2019) spanning multiple seasons; abundances of the single copy housekeeping gene rnpB from both clades were enumerated via quantitative PCR. We conducted a suite of statistical analyses to assess Trichodesmium clade abundances in the context of the physicochemical data. We observed a consistent coastal vs. open ocean separation of the two clades: T. erythraeum was found in shallow waters where the concentrations of dissolved iron (dFe) and the groundwater tracer Ba were significantly higher, while T. thiebautii abundance was positively correlated with water column depth. The Loop Current intrusion in 2015 with entrained Missisippi River water brought higher dFe and elevated abundance of both clades offshore of the 50 m isobath, suggesting that both clades are subject to Fe limitation on the outer shelf. Whereas, previous work has observed that T. thiebautii is more abundant than T. erythraeum in open ocean surface waters, this is the first study to examine Trichodesmium niche differentiation in a coastal environment. Understanding the environmental niches of these two key taxa bears important implications for their contributions to global nitrogen and carbon cycling and their response to global climate change.

Coexistence of similar species can be influenced by the intensity of interspecific interactions, which often depends on the availability of limiting resources. Habitat availability varies strongly with tidal phase in many intertidal ecosystems, potentially affecting interspecific interaction strength, particularly for mobile species. Four closely related species of highly mobile intertidal detritivores (talitrid amphipods Megalorchestia californiana, M. corniculata, M. benedicti, M. minor) inhabit sandy beaches in southern California, where they consume wave‐cast macroalgal wrack originating on coastal reefs. Their coexistence suggests that mechanisms, such as niche separation, are operating to weaken competition among these species. To evaluate this possibility, we explored how tidal phase may mediate temporal and spatial patterns of habitat use among these closely related congeners. We hypothesized that neap tides that reduce intertidal habitat would strengthen temporal separation between species, whereas spatial separation would be greater during spring tides when more habitat is available. We investigated these questions during spring and neap tide phases using (1) comparisons of intertidal distributions of burrowed amphipods and (2) observations of surface activity of amphipods from pitfall traps and mesocosms. We found significant effects of tide phase and species identity on mean intertidal positions and separation of burrowed amphipods. Intertidal distributions of the four species overlapped during neap tide and were significantly separated during spring tide when more intertidal habitat was available. Surface activity patterns differed among species and were more widely separated in time during neap tide than during spring tide. Consequently, the cumulative activity time of all species on neap tides was twice that observed during spring tides. Our findings suggest that mobile intertidal species, like these sympatric talitrid amphipods, can avoid interspecific competition by shifting their activity patterns with tide phase and beach condition. As rising sea levels reduce beach habitat, interspecific competition among these important intertidal consumers may increasingly influence their behavior and coexistence. [ABSTRACT FROM AUTHOR]

Abstract Coexistence of similar species can be influenced by the intensity of interspecific interactions, which often depends on the availability of limiting resources. Habitat availability varies strongly with tidal phase in many intertidal ecosystems, potentially affecting interspecific interaction strength, particularly for mobile species. Four closely related species of highly mobile intertidal detritivores (talitrid amphipods Megalorchestia californiana, M. corniculata, M. benedicti, M. minor) inhabit sandy beaches in southern California, where they consume wave‐cast macroalgal wrack originating on coastal reefs. Their coexistence suggests that mechanisms, such as niche separation, are operating to weaken competition among these species. To evaluate this possibility, we explored how tidal phase may mediate temporal and spatial patterns of habitat use among these closely related congeners. We hypothesized that neap tides that reduce intertidal habitat would strengthen temporal separation between species, whereas spatial separation would be greater during spring tides when more habitat is available. We investigated these questions during spring and neap tide phases using (1) comparisons of intertidal distributions of burrowed amphipods and (2) observations of surface activity of amphipods from pitfall traps and mesocosms. We found significant effects of tide phase and species identity on mean intertidal positions and separation of burrowed amphipods. Intertidal distributions of the four species overlapped during neap tide and were significantly separated during spring tide when more intertidal habitat was available. Surface activity patterns differed among species and were more widely separated in time during neap tide than during spring tide. Consequently, the cumulative activity time of all species on neap tides was twice that observed during spring tides. Our findings suggest that mobile intertidal species, like these sympatric talitrid amphipods, can avoid interspecific competition by shifting their activity patterns with tide phase and beach condition. As rising sea levels reduce beach habitat, interspecific competition among these important intertidal consumers may increasingly influence their behavior and coexistence.

Forest ecosystems have a distinct vertical dimension, but the structuring of communities in this three-dimensional space is not well understood. Water-filled tree holes are natural microcosms structured in metacommunities. Here, we used these microcosms as model systems to analyze how insect communities and the occurrence and abundance of individual species are influenced by biotic and abiotic microhabitat characteristics, the vertical position of the tree hole, and stand-scale habitat availability. We found that both the characteristics of water-filled tree holes and their insect communities differ significantly between canopy and ground level. Individual insect species showed contrasting responses to the vertical position of the tree holes when important environmental factors at the stand and the tree-hole scale were considered. While some species, such as the mosquito Aedes geniculatus and the beetle Prionocyphon serricornis, decreased in abundance with increasing tree-hole height, the biting midge Dasyhelea sp., the non-biting midge Metriocnemus cavicola and the hoverfly Myiatropa florea increased in abundance. Our results suggest that vertical stratification in forests is most likely driven not only by variation in tree-hole microhabitat properties, i.e., niche separation, but also by individual species traits, such as adult dispersal propensity, food preferences and mating behavior of adult stages, and interspecific competition of larval stages. Therefore, communities of insect species developing in tree holes are likely structured by competition–colonization trade-offs predicted by metacommunity theory.

Synchrony in ecological systems, the degree to which elements respond similarly over time or space, can inform our understanding of how ecosystems function and how they are responding to global change. While studies of ecological synchrony are often focused on within‐species dynamics, synchrony among species may provide important insights into how dynamics of one species are indicative of conditions relevant to the larger community, with both basic and applied implications. Ecological theory suggests there may be conditions under which communities might exhibit increased synchrony, however, the degree to which these patterns are borne out in natural systems is currently unknown. We used long‐term breeding success data from a community of Antarctic seabirds to assess the degree of interspecific, community synchrony, and the role that extreme events play in driving these dynamics. We assessed theoretical links between community synchrony, niche separation, and environmental variability using data from this and three other seabird communities as well as a simulation study. Results show that reproductive success for individual species in the Antarctic seabird community fluctuated relatively independently from one another, resulting in little synchrony across this community, outside of extreme years. While an exceptionally poor year for a given species was not necessarily associated with an exceptionally poor year for any other species, one community‐wide extreme year existed. When compared to other seabird communities, this group of Antarctic seabirds exhibited lower overall synchrony and higher estimated niche separation, supporting theoretical predictions. Empirical and simulation‐derived results suggest that communities where temporal variation is small for conditions in which species respond substantially differently, and large for conditions in which species respond similarly, may exhibit more synchronous dynamics. Identifying where and why synchronous dynamics might be more apparent has the potential to inform how ecological communities might respond to future global change. [ABSTRACT FROM AUTHOR]

Abstract Niche differentiation is a key concept in the field of ecology and refers to the process by which competing species within an ecological community partition utilization of environmental resources to achieve coexistence. The existence of niche differentiation is uniquely difficult to prove on account of the fact that historical interaction among species, which plays a key role in elucidating the current state of coexistence among species, is not well known. We created continuous niche gradients in nest‐site resources between two sympatric secondary cavity‐nesting birds, the green‐backed tit (Parus monticolus) and the russet sparrow (Passer cinnamomeus), and investigated whether nesting site is a factor contributing to limiting breeding overlap by regular inspection and 388,160 min of film recording. Our results indicate that although we manipulated nest site availability to be uniformly high along the habitat gradient, the two bird species have little overlap in nest sites and rarely compete for them. Furthermore, the green‐backed tit possessed a wide range of fundamental niche that covered that of the russet sparrow, while their reproductive time was largely segregated. The sparrow was more aggressive and outcompeted the tit in their overlapped range. These results suggest that even though nesting sites are crucial to the reproduction of cavity‐nesting birds, some other factor plays a more important role in limiting niche overlap between sparrows and tits in space and time. Given that these two cavity‐nesting birds continued to use different habitats and breed in segregated time after our manipulation, their relationship is better explained by the ghost of competition past theory.

On an evolutionary time scale, competition for food drives species formation by genetic adaptations to the environment and subsequent niche separation. On a short-term scale, animals use different strategies to meet their nutritional requirements, which ultimately influence their fitness. Understanding these adaptations in herbivores is especially important in temperate climates where animals have adapted both physiologically and behaviorally to seasonal variations in order to meet their nutritional requirements. The aim of this project was to investigate temporal variation in chemical composition of rumen content between two coexisting species of large herbivores, the native roe deer (Capreolus capreolus L.) and the introduced fallow deer (Dama dama L.), as well as a potential effect of competition on niche separation (interspecific differences in rumen nutrient composition). We analyzed 345 rumen samples collected from animals at one 95 km2 estate, Koberg, in southwestern Sweden. Based on samples from all seasons, temporal variation in nutrient composition and interspecific differences between the two deer species were investigated under two contrasting fallow deer population densities. Results revealed that nutrient composition varied between species and across seasons. Roe deer had a higher proportion of rumen protein compared to fallow deer, with the highest proportions in spring. In contrast, fallow deer had a higher proportion of rumen hemicellulose compared to roe deer in spring, while no differences in nutrient composition between species could be found in fall. Overall, there were greater differences between the two species when fallow deer density was high and competition likely more pronounced than when fallow deer density was low. The results from this study can be used to understand interspecific competition and how it fosters niche separation between coexisting large herbivores. [ABSTRACT FROM AUTHOR]

Niche separation between competing species is a central issue in ecology. As two of the most important pests worldwide of cereal production, Rhopalosiphum padi primarily dominates stems and basal leaves of wheat plants, whereas Sitobion avenae is common on the upper leaves and ears. Here, we investigated this microniche separation by considering effects of food resources and microclimates on the behavior and performance of R. padi and S. avenae on tissues from individual wheat seedlings. Wheat leaves provided favorable food for both aphid species and this tissue had high free amino acid and low soluble sugar compared with wheat stems. Both species preferred microclimates in the lower area of the seedlings where humidity was relatively higher and temperatures were relatively lower. In terms of performance, R. padi was more sensitive to microclimate effects than S. avenae, while the latter species was relatively more sensitive to limiting food resources. These factors may help explain why R. padi is relatively more common on lower microhabitats of seedlings, in contrast to S. avenae, contributing to the microspatial distribution of these species more generally. This information contributes to a better understanding of the relationship between these aphids and their host plants, which may assist in control strategies targeting these aphids. [ABSTRACT FROM AUTHOR]

The short-term variation in the abundance of Acartia copepods in the eutrophic Gamak Bay of South Korea was investigated with weekly measurements from October 2007 to September 2008. During this period, four Acartia species (A. erythraea, A. ohtsukai, A. omorii, and A. sinjiensis) were recorded as showing seasonally different peak abundance. The abundance of A. erythraea and A. sinjiensis was high in autumn, whereas that of A. omorii was high from winter to spring. In summer, A. erythraea, A. ohtsukai, and A. sinjiensis coexisted at peak abundance significantly related to water temperature and salinity. Results from the response curves of the four Acartia species to water temperature and salinity suggest that A. erythraea and A. sinjiensis increased in abundance at water temperatures >18 °C, whereas A. ohtsukai increased in abundance at water temperatures >27 °C. The occurrence of A. erythraea, A. ohtsukai, and A. sinjiensis decreased with increasing salinity, but chlorophyll-a concentration showed no effect on occurrence. Despite these findings, the coexistence of the three ecologically similar species may be due to prey abundance in summer and autumn (chlorophyll-a concentration >10 µg L−1). Notably, the wide range of the response curve of A. omorii indicates its occurrence at higher salinity levels than other species.

Photorhabdus spp. (Enterobacteriales: Morganellaceae) occur exclusively as symbionts of Heterorhabditis nematodes for which they provide numerous services, including killing insects and providing nutrition and defence within the cadavers. Unusually, two species (Photorhabdus cinerea and Photorhabdus temperata) associate with a single population of Heterorhabditis downesi at a dune grassland site. Building on previous work, we investigated competition between these two Photorhabdus species both at the regional (between insects) and local (within insect) level by trait comparison and co-culture experiments. There was no difference between the species with respect to supporting nematode reproduction and protection of cadavers against invertebrate scavengers, but P. cinerea was superior to P. temperata in several traits: faster growth rate, greater antibacterial and antifungal activity and colonisation of a higher proportion of nematodes in co-culture. Moreover, where both bacterial symbionts colonised single nematode infective juveniles, P. cinerea tended to dominate in numbers. Differences between Photorhabdus species were detected in the suite of secondary metabolites produced: P. temperata produced several compounds not produced by P. cinerea including anthraquinone pigments. Bioluminescence emitted by P. temperata also tended to be brighter than that from P. cinerea. Bioluminescence and pigmentation may protect cadavers against scavengers that rely on sight. We conclude that while P. cinerea may show greater local level (within-cadaver) competitive success, co-existence of the two Photorhabdus species in the spatially heterogeneous environment of the dunes is favoured by differing specialisations in defence of the cadaver against differing locally important threats. [ABSTRACT FROM AUTHOR]

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We assessed the potential competitive exclusion of southern bushbuck (hereafter bushbuck, Tragelaphus scriptus) by nyala (Tragelaphusangasii), the larger of the two spiral‐horned browsing antelopes (members of the Tragelaphine family). It has been suggested that high concentrations of nyala, capable of browsing a greater breadth of food items, negatively influence bushbuck. Using camera trap data, we explored factors influencing spatio‐temporal activity patterns and co‐occurrence of both species within three Protected Areas (PAs) of the Maputaland Conservation Unit, South Africa. Bushbuck have gone locally extinct within one of our survey areas, likely because of competitive pressures and cascading effects. Our results indicated a segregation of activities; bushbuck was more nocturnal, particularly in areas with higher nyala occupancy. Nyala occupancy overall was higher than bushbuck. When comparing occupancies at the management level, bushbuck occupancy was higher than nyala within two survey areas: where nyala were modelled as present but populations were managed through culling, and where leopard (Panthera pardus) populations were highest. Co‐occurrence was most likely in these two survey areas, indicating a threshold of nyala occupancy up to which bushbuck were tolerant. Where nyala were present in conjunction with high leopard density, bushbuck occupancy was higher. Conversely, where leopard density was low, the cascading effect was of high nyala occupancy, with subsequent competitive exclusion of bushbuck. Our results have critical management implications for PAs, including the management of carrying capacities, the preservation of native species assemblages and habitat management. We provide evidence that a larger‐bodied sympatric species can outcompete subordinate sympatric browsers when not effectively managed, particularly where the predation effects that influence population dynamics are limited. [ABSTRACT FROM AUTHOR]

Syntopic species often exhibit evolutionary mechanisms that reduce competition. A common mechanism facilitating coexistence is niche separation, which may manifest through spatial, temporal or trophic dimensions. Species that are morphologically similar, such as congeners, are likely to compete directly and thus separate their niche spatially. The microhabitat selection and partitioning of two endemic geckos of the Soutpansberg Mountains, Lygodactylus incognitus (Jacobsen, 1992; Squamata: Gekkonidae) and L. soutpansbergensis (Jacobsen, 1994; Squamata: Gekkonidae), was investigated by recording fine‐ and broad‐scale habitat variables. Results reveal that L. incognitus is restricted to high elevations above 1100 m a.s.l. and is associated with moist microclimates. Although primarily saxicolous, they also utilise tree trunks, branches and stems. Lygodactylus soutpansbergensis occurs above 800 m a.s.l and is restricted to rocky outcrops, open woodlands and rocky grasslands, often found on loose rocks. Perch height for L. soutpansbergensis is close to ground level, and they are limited to drier microclimates. Microhabitat partitioning does not appear to be due to interspecific exclusion as the smaller L. soutpansbergensis occupies the same niche dimensions in areas where L. incognitus is not present. Sites where L. incognitus occurs in the absence of L. soutpansbergensis are forested with high canopy cover, likely preventing the colonisation of L. soutpansbergensis. This suggests that morphological and physiological constraints define microhabitat limits, although this still requires testing. Anthropogenic activities are likely to threaten the persistence of L. incognitus and L. soutpansbergensis on the Soutpansberg in the future. The results from this study may aid the interpretation and understanding on the syntopy of morphologically similar species that inhabit the same macrohabitats in other areas. [ABSTRACT FROM AUTHOR]

Aims: Separating the effect of resource competition from allelopathy in plants is challenging and it has never been attempted in closely related co-occurring bryophytes. In peatlands, peat mosses (Sphagnum spp.) show niche differentiation along water table level (WTL) gradient. Our aim was to evaluate whether the hummock species, S. magellanicum would be a winner at low WTL due to its allelopathic advantage and the hollow species, S. angustifolium would win by virtue of its superior competitive ability but not of allelopathy at high WTL due to dilution of its allelochemicals. Methods: We used a nested, field experimental design, with two WTL treatments—low WTL (hummock habitat) and high WTL (hollow habitat)—and three different inter-specific interactions: 1) monoculture; 2) mixed culture without activated charcoal; and 3) mixed culture with activated charcoal added to the neighbor. We measured growth and biochemical traits of the two species and compared the index of relative neighbor effect on each other. Results: We discovered a trade-off between biomass production (competitive outcome) and phenolic content (allelopathy) in these species. At low WTL, allelopathy of the hummock species is the main mechanism to suppress the hollow species, whereas at high WTL, competition is the main driver to suppress the hummock species. Conclusions: Competitive advantage in Sphagnum is mediated by both resource competition and allelopathy of the co-occurring species through niche differentiation along a WTL gradient. Unlike vascular plants, Sphagnum mosses can serve as excellent model organisms in studying allelopathic interaction since they bypass the complexity of plant-soil interactions. [ABSTRACT FROM AUTHOR]

1. Although polyphagy is widespread among Drosophila, some specialist species have evolved in response to resource competition and other selection factors favouring niche separation. The small fruit specialist Drosophila suzukii Matsumura has evolved a unique serrated ovipositor that allows it to access ripening fruit, a niche unavailable to most Drosophila. However, it is unclear whether ancestral traits (the use of non‐fruit resources) are maintained in this specialist species. 2. In this study, maternal preferences and offspring fitness in response to novel apple, mushroom, and bird manure‐based diets were investigated by comparing oviposition and offspring survival and development on various diets. The effect of those diets on survival at cool temperatures and the effect of natal environment/previous exposure on adult preferences were evaluated. 3. Female D. suzukii accepted non‐fruit diets such as mushroom and bird manure, and offspring completed their larval development on all diets tested. However, D. suzukii did not perform well on diets that included bird manure. By contrast, combinational apple/mushroom diets were associated with greater oviposition, lower mortality, faster development, and larger offspring than other diets. These diets were also associated with increased resistance to cold stress, and preference for these diets was positively affected by previous feeding experience. 4. These data suggest that D. suzukii may use non‐fruit resources when preferred resources are scarce. Given that this pest is adapted to temperate climates, alternative resources might provide seasonal nutritional support when fruit resources are not temporally available, although field data are needed to support this hypothesis. [ABSTRACT FROM AUTHOR]

Niche differentiation is a key concept in the field of ecology and refers to the process by which competing species within an ecological community partition utilization of environmental resources to achieve coexistence. The existence of niche differentiation is uniquely difficult to prove on account of the fact that historical interaction among species, which plays a key role in elucidating the current state of coexistence among species, is not well known. We created continuous niche gradients in nest‐site resources between two sympatric secondary cavity‐nesting birds, the green‐backed tit (Parus monticolus) and the russet sparrow (Passer cinnamomeus), and investigated whether nesting site is a factor contributing to limiting breeding overlap by regular inspection and 388,160 min of film recording. Our results indicate that although we manipulated nest site availability to be uniformly high along the habitat gradient, the two bird species have little overlap in nest sites and rarely compete for them. Furthermore, the green‐backed tit possessed a wide range of fundamental niche that covered that of the russet sparrow, while their reproductive time was largely segregated. The sparrow was more aggressive and outcompeted the tit in their overlapped range. These results suggest that even though nesting sites are crucial to the reproduction of cavity‐nesting birds, some other factor plays a more important role in limiting niche overlap between sparrows and tits in space and time. Given that these two cavity‐nesting birds continued to use different habitats and breed in segregated time after our manipulation, their relationship is better explained by the ghost of competition past theory. [ABSTRACT FROM AUTHOR]

• Long-term data indicate zonation between Polygonum ferrugineum and P. acuminatum. • P. acuminatum escaped inundation stress by shoot elongation, but not P. ferrugineum. • P. acuminatum has higher competitive ability than P. ferrugineum regardless of the water level. • The water level is the primary factor determining zonation between these species. We assessed the zonation of two emergent macrophytes, Polygonum ferrugineum and Polygonum acuminatum, and experimentally tested the effects of water level fluctuations and competition on the growth of these two species. We modelled the abundance of both species as a function of depth using a Bayesian approach based on a 16-year dataset from a subtropical floodplain. Then, we designed a factorial experiment in which species were planted in monocultures and mixtures and subjected to three water level treatments (low, high and variable) for 30 days. All response variables and relative yields were analysed with a two-way ANOVA. The modelled data showed that the two species colonize different depths, with P. acuminatum colonizing shallower areas than P. ferrugineum. Biomass accumulation did not differ between species in monocultures, but P. acuminatum showed significantly higher shoot and internode lengths when it grew submerged, indicating different survival strategies between the two species. P. acuminatum resisted inundation through an escape strategy, elongating above the water surface, while P. ferrugineum did not show this strategy. In mixtures, P. acuminatum showed a significantly higher competitive ability than P. ferrugineum , indicating that the former species has advantages over the latter during the colonization phase. These results are consistent with our observational results because they show that P. acuminatum can dominate in shallower areas by having morphological adaptations to intermittent fluctuations in water level and a competitive advantage over P. ferrugineum. [ABSTRACT FROM AUTHOR]

To explore the difference in pollen harvest between the western honey bee Apis mellifera and a native eastern honey bee A. cerana in the Zoige alpine meadows in the northeastern part of the Qinghai-Tibetan Plateau, we investigated species diversity of the harvested pollen and the amount of harvested pollen per bee for both species, and calculated the niche overlap (in terms of similarity in harvested pollen) between the two bee species during the flowering season from June to August 2016. Results showed that the species diversity of the harvested pollen was indistinguishable between the two bee species. Nevertheless, A. mellifera carried more (although not significant) pollens per bee than A. cerana. Moreover, pollen composition differed between the two bee species: A. mellifera mainly foraged on Anemone rivularis, Saussurea nigrescens and Anemone trullifolia, while A. cerana foraged on Anemone rivularis, Stellera chamaejasme, and Pedicularis longiflora. Consistently, the niche overlap between the two honeybee species was particularly small in several observations. Our results indicate a niche separation in pollen resource between the two honeybee species in a Tibetan alpine meadow. [ABSTRACT FROM AUTHOR]

Entomopathogenic fungi from the genera Beauveria and Metarhizium , were isolated from soil using the Galleria mellonella baiting method, and from infected white grub larvae from a diversity of cropping systems in Puebla and Guanajuato, Mexico. Isolates were identified to species level using Bloc and Elongation Factor 1-α sequence information. Although widespread, Beauveria bassiana (41 isolates) was only isolated from soil and not from infected white grubs. In contrast, Beauveria pseudobassiana (six isolates) was predominantly isolated from white grub larvae (only one isolate from soil). Haplotype analysis of B. bassiana Bloc sequences identified 25 haplotypes indicating substantial genetic diversity; neither geographical origin nor crop type explained this genetic variation. Metarhizium brunneum (three isolates) and Metarhizium robertsii (17 isolates) were also only isolated from soil, while Metarhizium anisopliae (six isolates) and Metarhizium pingshaense (four isolates) were only isolated from white grub larvae. M. anisopliae was only found infecting Paranomala species while M. pingshaense was only found infecting Phyllophaga species. Species diversity in Metarhizium was influenced by crop type. Our results showed that entomopathogenic fungi species could co-exist in the same soil ecosystem but in separate niches. The potential ecological roles of these species are discussed. Image 1 • Beauveria and Metarhizium were isolated from soil and white grub larvae. • B. bassiana s.s., M. brunneum and M. robertsii were only isolated from soil. • B. pseudobassiana was predominantly isolated from white grub larvae. • M. anisopliae s.s. and M. pingshaense were only isolated from white grub larvae. • Niche separation was clear amongst species suggesting different ecological roles. [ABSTRACT FROM AUTHOR]

Abstract The coexistence of ecologically similar species is often assumed to be facilitated by differential resource and habitat use. For sandy beach ecosystems characterized by low primary productivity, a suite of intertidal consumers relies on subsidies of allochthonous marine macrophytes, or wrack, as both food and habitat. To investigate how intertidal consumers may partition macrophyte wrack resources on sandy beaches, we measured individual consumption rates of four talitrid amphipod species (Megalorchestia spp.) on five macrophyte species in laboratory and field trials. Laboratory rates of consumption of macrophytes differed significantly among consumers, but general patterns were similar. Feather boa kelp (Egregia menziesii), was consumed at the highest rate by all species, rather than the more abundant giant kelp (Macrocystis pyrifera). In the field trials, talitrid amphipods were more abundant under experimental wrack patches containing kelps, and consumption of feather boa kelp was higher than for giant kelp or surf grass (Phyllospadix torreyi). Our results demonstrate that a suite of co-occurring talitrid amphipod species rely heavily on kelp wrack and suggest that these abundant intertidal consumers do not partition wrack resources. Highlights • Feeding rates suggest that wrack consumers do not partition food resources. • Talitrid amphipods consumed a less abundant kelp species at a higher rate. • Consumers preferentially colonized wrack patches containing kelps. [ABSTRACT FROM AUTHOR]

In this study, we investigated the habitat, the daily activity and the trophic niche overlap of three carnivores found in southern Tunisia, namely the fennec fox (Vulpes zerda), the red fox (Vulpes vulpes) and the African golden wolf (Canis anthus) over seasons. To achieve this goal, we surveyed 300-meter transects in Sidi Toui National Park (N=29) and in Oued Dekouk Natural Reserve (N=24) over a year. Using information provided by camera trap photos and scats analysis; we determined daily activities and diets of the three canids. African golden wolves and red foxes shared most of their habitat in the two areas, especially in Sidi Toui National Park, while fennec foxes were restricted to the sandy area in Oued Dekouk Natural Reserve. Based on 729 photos produced by camera trap, we observed that the African golden wolf had a continuous activity through the day and the year, while the red fox and the fennec fox were active also through the year but mainly during twilight. We were able to identify food items from 504 scats, which included fruits, invertebrates, rodents, lagomorphs, birds, reptiles and livestock. Our results showed a significant variation in the diets between the species, seasons and sites. Rodents and livestock represented, respectively, 11.7% and 19.2% of the biomass consumed by the African golden wolf over the year. Both foxes ate invertebrates and rodents with different frequency during the seasons. The trophic niche overlap was very high between the two foxes (O j k > 0.95) and partial between each fox species and the wolves (O j k < 0.65). The knowledge of the habitat and the trophic niche overlap of these three carnivores increases our understanding of factors responsible for their coexistence, which may help to improve management and conservation actions. [ABSTRACT FROM AUTHOR]

Graphical abstract Highlights • Over two years we surveyed 250 sites, each within two seasons using camera traps. • We explored anthropogenic influences on antelope spatio-temporal activity patterns. • Anthropogenic pressures in combination with novel predators influenced activity patterns. • Sympatric species exhibited spatial and some temporal segregation of activity. • Niche separation was driven by facultative and ecological influences in the anthropogenic landscape. Abstract Understanding the effects of anthropogenic disturbance on species' behaviour is crucial for conservation planning, considering the extent of habitat loss. We investigated the influence of anthropogenic disturbances including agriculture, urbanisation, protected areas, and the presence of novel predators, on the temporal and spatial behaviour of sympatric forest antelope (Tragelaphus scriptus, Philantomba monticola, Sylvicapra grimmia, and Cephalophus natalensis) in an anthropogenic matrix containing forest fragments in the Indian Ocean Coastal Belt of South Africa. We integrated land-use types with camera-trap data and compared activity patterns using circular statistics and occupancy modelling. Antelope species overlapped in temporal and spatial distribution and exhibited diurnal activity for 50% of the time. All species exhibited nocturnal activity for ∼25–33% of all observations, except for C. natalensis. Nocturnal activity varied between species and land-use types. The predators Canis familiaris , C. mesomelas and Caracal caracal negatively influenced occupancy of P. monticola , S. grimmia and C. natalensis. Humans negatively influenced temporal activity of P. monticola , and spatial distribution of T. scriptus and S. grimmia. C. familiaris had an overall negative influence on S. grimmia. We found spatial, and to a lesser extent temporal, segregation between species. However, plasticity in activity patterns existed, which varied in response to anthropogenic effects and novel predators. [ABSTRACT FROM AUTHOR]

With the strategy of development driven by innovation, the innovation and entrepreneurship education in colleges and universities has been changing and developing steadily from the perspective of ecosystems. However, the ecosystem is fragmented and lacks synergy as before. It cannot meet the market demand of innovative and entrepreneurial talents and the need for self-worth of the college students. In order to enhance the effectiveness of innovation and entrepreneurship education in colleges and universities and improve the quality of the innovative talents, this paper builds the ecosystem of innovation and entrepreneurship education in colleges and universities, relying on the collaborative innovation platform required by regional economic and social development and industrial transformation and upgrading. It introduces Niche theory to analyze the Niche relationship of ecological factors, and studies the interaction mechanism of various elements of ecosystem by the strategy of Niche separation, expansion and co-evolution, making the complementary advantages and co-evolution of the ecological elements of innovation and entrepreneurship education have been realized, and promoting the dynamic balance of the innovation and entrepreneurship education ecosystem in colleges and universities. [ABSTRACT FROM AUTHOR]

Selecting appropriate plant species is required for effective vegetational restoration. Phragmites australis and Phragmitesjaponica are large perennial grasses frequently used for restoration of wetland ecosystems. They have different distribution ranges along stream. We analysed plant density, stream slope, and physicochemical characteristics of soil at their habitats to distinguish environmental factors responsible for the distribution ranges. P. japonica was distributed at upper stream side with average slope of 8.4 m/km whereas P. australis inhabited at lower stream side with average slope of 1.7 m/km. Moisture content, organic matter, PO4‐P, NH4‐N, K+, and Ca2+ contents in soil were significantly higher at habitats of P. australis than those at habitats of P. japonica. Canonical correspondence analysis showed that NH4‐N, K+, and organic matter contents had the strongest influences on the density of these two species. The density of P. australis and P. japonica can be explained by the following multiple linear regression models with soil NH4‐N and K+ contents: DPJ = 97.471–0.052CNH4‐N − 0.185CK and DPA = 7.533 + 0.135CNH4‐N + 0.032CK (DPA = Density of P. australis, DPJ = Density of P. japonica, CNH4‐N = Content of NH4‐N, CK = Content of K+). These models can be used as references to select P. japonica or P. australis for restoring stream ecosystem. [ABSTRACT FROM AUTHOR]

Abstract: Water source separation can be one of strategies for different plant species to coexist in a community. This study first demonstrates mechanisms of water source separation during vegetation succession. An isotope‐incorporated mechanistic model was employed to simulate the xylem water isotopic composition and the root water uptake profile for a Pinus densiflora–Quercus myrsinaefolia mixed stand undergoing secondary succession and a pure P. densiflora stand before succession. In the mixed stand, the model successfully simulated the xylem water isotopic composition on the assumption that the root surface resistance per unit length of root (rrs*) decreases with increasing depth for P. densiflora but is constant for Q. myrsinaefolia. Uptake fraction for P. densiflora was greater in deeper zones but in shallower for Q. myrsinaefolia. In contrast, in the pure stand, a constant rrs* for P. densiflora gave good reproducibility in isotope simulation and shallow water uptake dominated. These findings highlight root functional change as a mechanism of water source separation; pre‐existing P. densiflora trees decrease their deep‐root rrs* to compensate for an increase in shallow‐root rrs*. This mechanism was caused by competition against invading Q. myrsinaefolia trees. [ABSTRACT FROM AUTHOR]

The northward range expansion of Tufted Titmice (Baeolophus bicolor) has increased their contact with Black-capped Chickadees (Poecile atricapillus). Tufted Titmice and Black-capped Chickadees were observed foraging naturally in 3 Connecticut forests and at a residential bird feeder to assess the degree of foraging niche overlap and competition between the 2 species during winter 2015–2016. Chickadees spent significantly more time in the outer portion of the upper canopy than did titmice, which used different subsections of the canopy fairly evenly. Chickadees also foraged in shrubs significantly more than did titmice. Titmice spent much of their time foraging on the ground, which chickadees largely avoided. These differences may be explained by the ability of larger titmice to better forage on larger branches and to flip leaves to forage on the ground. The larger size of titmice may also explain their dominance to chickadees at the bird feeder. Given a choice between safflower seeds, black oil sunflower seeds with shells, and black oil sunflower seeds without shells, both species took some of each, but titmice most often chose safflower seeds while chickadees most often chose black oil sunflower seeds without shells. Although chickadees and titmice showed some overlap in their food choices and foraging locations, the significant differences we found may mitigate competition between these species, at least under the environmental conditions of this study. As titmice continue to expand their range northward, competition may be greater in areas with harsher winter conditions and less human-supplied bird seed. [ABSTRACT FROM AUTHOR]

Summary: The influence of soil temperature on rhizome depths of four intertidal seagrass species was investigated in central Queensland, Australia. We postulated that certain intertidal seagrass species are soil temperature‐sensitive and vertically stratify rhizome depths. Below‐ground vertical stratification of intertidal seagrass rhizome depths was analysed based upon microclimate (soil temperature) and microhabitat (soil type). Soil temperature profiles exhibited heat transfer from surface layers to depth that varied by microhabitat, with vertical stratification of rhizome depths between species. Halodule uninervis rhizomes maintain a narrow median soil temperature envelope; compensating for high surface temperatures by occupying deeper, cooler soil substrates. Halophila decipiens, Halophila ovalis and Zostera muelleri rhizomes are shallow‐rooted and exposed to fluctuating temperatures, with broader median temperature envelopes. Halodule uninervis appears to be a niche specialist, with the two Halophila species considered as generalist niche usage species. The implications of niche use based upon soil temperature profiles and rhizome rooting depths are discussed in the context of species’ thermal tolerances and below‐ground biomass O2 demand associated with respiration and maintenance of oxic microshields. This preliminary evidence suggests that soil temperature interaction with rhizome rooting depths may be a factor that influences the distribution of intertidal seagrasses. [ABSTRACT FROM AUTHOR]

Purpose: Nitrification, the microbial oxidation of ammonia to nitrate via nitrite, is a pivotal component of the biogeochemical nitrogen cycle. Nitrification was conventionally assumed as a two-step process in which ammonia oxidation was thought to be catalyzed by ammonia-oxidizing archaea (AOA) and bacteria (AOB), as well as nitrite oxidation by nitrite-oxidizing bacteria (NOB). This long-held assumption of labour division between the two functional groups, however, was challenged by the recent unexpected discovery of complete ammonia oxidizers within the Nitrospira genus that are capable of converting ammonia to nitrate in a single organism (comammox). This breakthrough raised fundamental questions on the niche specialization and differentiation of comammox organisms with other canonical nitrifying prokaryotes in terrestrial ecosystems. Materials and methods: This article provides an overview of the recent insights into the genomic analysis, physiological characterization and environmental investigation of the comammox organisms, which have dramatically changed our perspective on the aerobic nitrification process. By using quantitative PCR analysis, we also compared the abundances of comammox Nitrospira clade A and clade B, AOA, AOB and NOB in 300 forest soil samples from China spanning a wide range of soil pH. Results and discussion: Comammox Nitrospira are environmentally widespread and numerically abundant in natural and engineered habitats. Physiological data, including ammonia oxidation kinetics and metabolic versatility, and comparative genomic analysis revealed that comammox organisms might functionally outcompete other canonical nitrifiers under highly oligotrophic conditions. These findings highlight the necessity in future studies to re-evaluate the niche differentiation between ammonia oxidizers and their relative contribution to nitrification in various terrestrial ecosystems by including comammox Nitrospira in such comparisons. Conclusions: The discovery of comammox and their broad environmental distribution added a new dimension to our knowledge of the biochemistry and physiology of nitrification and has far-reaching implications for refined strategies to manipulate nitrification in terrestrial ecosystems and to maximize agricultural productivity and sustainability. [ABSTRACT FROM AUTHOR]

Tree-grass coexistence is commonly observed in arid and semi-arid ecosystems. Many of these ecosystems are undergoing a shift from grassland to tree dominance or the opposite. Therefore, exploring the mechanism of tree-grass coexistence and studying how ecosystems respond to environmental change are critical to understanding such shift. We construct a tree-grass-water model by considering the Walter’s two layer hypothesis, i.e., the grass species only access to the shallow soil water, while the tree can uptake both the shallow and deep soil water. Results show that the tree-grass coexistence region increases with increasing their niche separation. Hence, the vertical niche separation between trees and grass with respect to limiting water resources might be one of mechanisms for tree-grass coexistence. Besides, both tree and grass display positive responses to precipitation, but surprisingly, there exists a catastrophe that the mean vegetation density first rapidly increases, but then quickly decreases as precipitation increases in the tree-grass-water model with infiltration feedback. Most likely, this catastrophe is due primarily to the periodical fluctuation of vegetation density and water caused by its intrinsic infiltration feedback. Overall, our study provides new insights into the dynamics of tree-grass in arid and semi-arid ecosystems. [ABSTRACT FROM AUTHOR]

The assessment of leaf strategies has been a common theme in ecology, especially where multiple sources of environmental constraints (fire, seasonal drought, nutrient-poor soils) impose a strong selection pressure towards leaf functional diversity, leading to inevitable tradeoffs among leaf traits, and ultimately to niche segregation among coexisting species. As diversification on leaf functional strategies is dependent on integration at whole plant level, we hypothesized that regardless of phylogenetic relatedness, leaf trait functional syndromes in a multivariate space would be associated with the type of growth form. We measured traits related to leaf gas exchange, structure and nutrient status in 57 coexisting species encompassing all Angiosperms major clades, in a wide array of plant morphologies (trees, shrubs, sub-shrubs, herbs, grasses and palms) in a savanna of Central Brazil. Growth forms differed in mean values for the studied functional leaf traits. We extracted 4 groups of functional typologies: grasses (elevated leaf dark respiration, light-saturated photosynthesis on a leaf mass and area basis, lower values of leaf Ca and Mg), herbs (high values of SLA, leaf N and leaf Fe), palms (high values of stomatal conductance, leaf transpiration and leaf K) and woody eudicots (sub-shrubs, shrubs and trees; low SLA and high leaf Ca and Mg). Despite the large range of variation among species for each individual trait and the independent evolutionary trajectory of individual species, growth forms were strongly associated with particular leaf trait combinations, suggesting clear evolutionary constraints on leaf function for morphologically similar species in savanna ecosystems. [ABSTRACT FROM AUTHOR]

The Japan Trench is located under the eutrophic Northwestern Pacific while the Mariana Trench that harbors the unique hadal planktonic biosphere is located under the oligotrophic Pacific. Water samples from the sea surface to just above the seafloor at a total of 11 stations including a trench axis station, were investigated several months after the Tohoku Earthquake in March 2011. High turbidity zones in deep waters were observed at most of the sampling stations. The small subunit (SSU) rRNA gene community structures in the hadal waters (water depths below 6000 m) at the trench axis station were distinct from those in the overlying meso-, bathy and abyssopelagic waters (water depths between 200 and 1000 m, 1000 and 4000 m and 4000 and 6000 m, respectively), although the SSU rRNA gene sequences suggested that potential heterotrophic bacteria dominated in all of the waters. Potential niche separation of nitrifiers, including ammonia-oxidizing archaea (AOA), was revealed by quantitative PCR analyses. It seems likely that Nitrosopumilus-like AOAs respond to a high flux of electron donors and dominate in several zones of water columns including shallow and very deep waters. This study highlights the effects of suspended organic matter, as induced by seafloor deformation, on microbial communities in deep waters and confirm the occurrence of the distinctive hadal biosphere in global trench environments hypothesized in the previous study.