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The Bolkar Mountain Viper, Montivipera bulgardaghica (Nilson & Andren, 1985), is a mountain viper found in the eastern Mediterranean region. In this study, we present data on the seasonal variation in diet composition across two different habitats in the Central Taurus Mountains of Anatolia, Türkiye. The Karboğazı population inhabits a subalpine shrubland, while the Göller Yaylası population resides in forested land. The vipers primarily consumed Lacertidae (47%), followed by Orthoptera (27%), Chilopoda (18%), and Scincidae (8%) in number. In spring, the diet of the Karboğazı population was mainly composed of Lacertidae but shifts toward Orthoptera during summer and autumn. In contrast, the Göller Yaylası population fed on Lacertidae throughout the entire active season. Overall, the Karboğazı population primarily consumed invertebrates, whereas the Göller Yaylası population predominantly fed on lizards. Both populations exhibited partial niche overlap. There was no significant difference in diet composition between sexes, but prey type and quantity varied with the season. Prey diversity increased in summer and decreased in autumn and spring, corresponding with the prey availability in the environment. [ABSTRACT FROM AUTHOR]

Dominant technology in high-tech industries refers to the technology that can break the stability and balance of the original technology system within a certain period and is widely adopted under the interaction of technological possibility and market choice. It is of theoretical and practical necessity to explore dominant technology's formation under overlapping niche. Thus, based on niche theory and competitive game theory, we established a competitive game model of dominant technology formation, and dynamically simulated the shape of dominant technology. This paper uses 'the proportion of user adoption' to measure dominant technology market share in high-tech industry and maintains that obtaining over 50% confers an obvious competitive advantage. Therefore, we draw three main conclusions: (1) Dominant technology formation in high-tech industry is influenced by R&D input, adopter preferences, adoption returns and the decision-making cost; (2) dominant technology formation under niche overlap can be described as a continuous accumulation and complex dynamic process; and (3) The main goal in the new technology competitive game is to obtain a larger market share, and the interaction in this game, which has two possible results, is complex, dynamic, diverse, and nonlinear. [ABSTRACT FROM AUTHOR]

Knowing the determinants of biodiversity is crucial to understanding the differentiation of living organisms. Several gene-flow limiting processes can drive divergence, including adaptive ecological differentiation or geographical isolation both constituting environmental-dependent reproductive barriers. Furthermore, the strength of these processes may be associated to the degree to which ecological niches are conserved and shared by phylogenetically related species. Here, we aim to disentangle these two alternatives reproductive barriers by evaluating the degree of ecological niche similarity among phylogenetically related species. We performed ecological niche modelling (ENM) on four species belonging to a recently diversified genus (Aquilegia, Ranunculaceae) occurring in montane environments of the Alpine and Apennine chains (southern Europe). Results show that niche differentiation among species is related to phylogenetic distinctiveness. Nevertheless, niche similarity tests indicated that the conditions selected by the species are more similar than expected from the null models, even though they are sparsely available in the respective ecological spaces, suggesting that the observed pattern may result from phylogenetic niche conservatism. These results, highlight that paleogeographic events in south-European mountains may have driven divergence by isolation in Aquilegia while partially retaining the possibly ancestral characters of the niches. [ABSTRACT FROM AUTHOR]

Approximately 33% of plant species face extinction due to climate change. Polyploidisation, a process resulting in more than two complete sets of chromosomes, may be promoted by periods of climate fluctuations. Ecological niche modelling (ENM) using occurrences of endemic plants in the North American Coastal Plain (NACP) biodiversity hotspot could be used to evaluate the potential effects of climate change on cytotype distributions. We used known diploid and polyploid taxa endemic to the NACP to test hypotheses that diploids and polyploids differed in habitat preferences, considerable overlap existed between cytotypes, and polyploid distributions would increase under climate change projections. We examined niche identity and overlap of 28 congeneric ploidy level pairs and performed ENM to evaluate how climate change could affect these groups. Congeneric ploidy level pairs differed significantly in niche identity, and overlap varied across genera. Eleven genera showed greater than 100% increases in habitat suitability and six genera showed almost no remaining suitable habitat in at least one future climate scenario. With 70% of the species that showed substantial declines in projected suitable habitat being of conservation concern, we propose that future studies of these genera should be a primary focus in the NACP. [ABSTRACT FROM AUTHOR]

To investigate divergences of ecological spatial niche dimensions, we evaluated if lizards Tropidurus hispidus and T. semitaeniatus used or selected structural (types of microhabitat and perch heights) and thermal resources (microhabitat temperatures and levels of sunlight) in ways that could ease living in syntopy. Most T. hispidus and T. semitaeniatus used rocks, resulting in a high overlap of structural niche dimensions. The former used such microhabitats according to the environmental availability and the latter selected rocks. Tropidurus hispidus selected shadier and colder microhabitats than T. semitaeniatus that selected warmer sites with full sunlight. Tropidurus semitaeniatus occupied regions further from vegetation shelters than from rock shelters. Larger T. semitaeniatus moved farther away from shelters than smaller individuals. Tropidurus hispidus perched higher than T. semitaeniatus. Distinctions regarding the use of spatial resources effectively reduced the overlaps of ecological niche dimensions, segregating the species and easing the life in syntopy. [ABSTRACT FROM AUTHOR]

This study estimates the diversity, abundance and floral associations of native wild bees present in a nature reserve in Buenos Aires, Argentina. The study included monthly sampling from September to April for two consecutive seasons (2011–2013). Bees were collected using entomological nets and pan traps along transects in the reserve area. A total of 1102 specimens belonging to 87 wild bee species/morphospecies in 37 genera of five families were collected. The families with the highest numbers of species were Apidae, followed by Halictidae and Megachilidae. A total of 63 species/morphospecies of plants belonging to 20 families were visited by bees. Asteraceae received the most visits, followed by Fabaceae and Onagraceae. Wild bee/plant interactions were studied through niche breadth and niche overlap. The highest values for niche breadth were found in two social species (Bombus pauloensis and Augochlora amphitrite) and niche overlap was predominantly low among bee species. Our results suggest that the nature reserve "Reserva Natural Integral Punta Lara" in northeastern Buenos Aires Province, Argentina, is an important natural area that supports a diverse community of wild bees. [ABSTRACT FROM AUTHOR]

Understanding the conditions under which interacting species can persist is a major goal in ecology. Dietary partitioning is one of the major strategies that enables ecologically similar species to coexist in communities. In this study, we examined the dietary patterns of a selected group of amphibians in an amphibian community in northern Sri Lanka to understand differential resource use by coexisting species. The stomach flushing method was used to examine the diet of amphibians to study the niche breadth and pairwise species dietary niche overlap. Seventeen different prey categories were identified from the diet of six species of amphibians in the community. The most frequently used prey category by all amphibians was hymenoptera. Among the amphibians, some consumed several different prey categories (8–9 prey categories), while some were more specialised (e.g. Uperodon rohani fed only on ants), consuming only one or two different prey categories. The average niche overlap among the species in the community was 0.392 indicating low trophic niche overlap. This study indicates a low level of dietary niche overlap between the selected amphibian species and hence, a high degree of dietary niche partitioning. The findings also provide valuable insights into the dietary ecology of these amphibians, which will be invaluable for the formulation of conservation strategies. [ABSTRACT FROM AUTHOR]

The Gray Toad-headed Agama (Phrynocephalus scutellatus) occurs in Iran, Pakistan and Afghanistan and is represented in Iran by four distinctive genetic clades. We built distribution models for three of these clades (one clade was not included due to a low number of distribution records) using Maximum Entropy Algorithm in order to determine the contribution of ecological factors to the distribution pattern. The degree of spatial niche overlap between every pair of clades were measured using Schoener's D niche overlap metric. The results showed that at species-level climate variables (annual precipitation, annual mean temperature) were the most influential parameters determining the boundaries of the distribution in Iran. Temperature seasonality was found to be the most influential factor in the distribution of both Clade I and Clade II. However, this variable was replaced by the annual mean temperature for Clade VI. Based on the results of Schoener's D metric, Clades I and II had the lowest, and Clades II and VI the highest level of ecological niche overlap. Comparing the result of niche overlap with genetic distance between the clades, it was found that the ecologically least similar clades were those with the longer history of genetic segregation. [ABSTRACT FROM PUBLISHER]

Don’t stand so close to me: competitive pressures, proximity and inter-organizational collaboration. Regional Studies. This paper investigates how geographical proximity moderates the non-monotonic relation between niche overlap and the propensity of organizations to collaborate. The main prediction is that the strength of this relation is different for organizations with low versus high levels of geographical proximity. Proposed hypotheses are tested by using data collected within a community of hospital organizations serving more than 5 million residents in one of the largest Italian geographical regions. After controlling for internal resource complementarities and differences in organizational forms, behavioural orientations and institutional constraints among hospitals, this paper finds strong empirical support to the research hypotheses. [ABSTRACT FROM AUTHOR]

Sediment characteristics, especially grain size, are usually considered the most important variables affectingUcadistribution, mainly due to its close relationship with mouth appendage morphology. The aim of this study was to verify, from an assemblage perspective, if sediment is the most important variable affectingUcaspecies distribution, and if mouth appendage morphology (setae type and curvature) would be related to habitat occupancy. Niche metrics and null model approaches were used to assess and test the hypothesis. The relevance of spoon-tipped setae curvature toUcadistribution was verified for the first time. A fragmented mangrove area was divided into seven subareas, and sampling of crabs and environmental variables took place in June and November 2010. Of 10 species recorded for Brazil, seven were found in the study area:U. burgersi,U. cumulanta,U. leptodactyla,U. maracoani,U. rapax,U. thayeriandU. uruguayensis.Multivariate analysis showed that sediment grain size and the presence of vegetation were the most important variables explaining distribution, reinforcing results commonly obtained by univariate approaches. The overlap of habitat occupancy was generally low and no relationship between mouth appendages was found with breadth and overlap measures. Contrary to predictions, most non-random overlap values were lower than expected by chance, suggesting that interspecific competition might influence species distribution. Also, variables such as the presence of vegetation are important and influence crab distribution, limiting the potential distribution that would be predicted by mouth adaptations alone. Thus, the use of these adaptations as surrogates of fiddler crab distribution is not recommended. [ABSTRACT FROM PUBLISHER]

Resource partitioning may allow species coexistence. Sand dunes in the typical steppe of Inner Mongolia, China, consist of desert, shrub and grass habitats, providing an appropriate system for studies of spatial niche partitioning among small mammals. We collected data to verify the niche separation hypothesis that coexisting small mammals would separate into spatial niches, and the productivity hypothesis that the highest species richness and overlap were to be expected in the most productive and diverse shrub habitat of the north-facing slopes, in contrast with the less productive grass and desert habitats of sand dunes. We trapped small mammals on 44 sand dunes in the summer of 1984 using snap traps. We captured 12 species of small mammals among three types of habitats.Cricetulus barabensiswas a habitat generalist, present in all three types of habitats.Spermophilus dauricuswas present only in the grass habitat,Allactaga sibiricaandDipus sagittaonly in the desert habitat, andApodemus peninsulaeprimarily in the shrub habitat. The shrub habitat hosted the largest number of small mammal species among the three types of habitats, supporting the productivity hypothesis. Habitat separation is an important mechanism for structuring small mammal communities in Inner Mongolia grasslands. [ABSTRACT FROM AUTHOR]

The study of the diet of tadpoles can provide important information about the maintenance and dynamics of populations and communities of tropical amphibians. Tadpoles are in general herbivores and consume mostly algae. Despite this, little is known about how specific guilds use resources that are available in the same space and at the same time. It is thought that species of tadpoles segregate based on food use, especially in lotic environments where food resources may be a limiting factor. Conversely, it is believed that the use of food resources is similar among tadpoles with the same ecomorphotype. This study examined the diet ofAplastodiscus cavicola,Aplastodiscus sibilatusandBokermannohyla caprasyntopic tadpoles, as similarities may exist between these benthic species, all of which are adapted to the flow of water. This study was undertaken in the Michelin Ecological Reserve, municipality of Igrapiúna, state of Bahia, Brazil. To analyze the diet of the tadpoles, nonmetric multidimensional scaling (NMDS) was performed to evaluate the similarity between the diets of the species. Analysis of similarity (ANOSIM) was carried out to detect whether diet differed among tadpole species. The diet of these tadpoles consists mainly of algae, especially diatoms, plants, protozoa, fungi and microscopic animals. The NMDS identified three clusters representing the three species studied. ANOSIM detected significant differences among the diets of the species, which indicates partition of food resources. [ABSTRACT FROM AUTHOR]

We studied patterns of microhabitat use by adults of two sympatricBokermannohylaspecies at the Reserva Particular do Patrimônio Natural Santuário do Caraça, southeastern Brazil. We selected three streams, one where both species occurred in syntopy and the other two where each one occurred alone. We sampled 150-m transects in each stream throughout 1 year, recording microhabitat features for each frog located (substrate type, height and distance from water). Microhabitat availability varied between dry and wet seasons in all streams, and overall microhabitat diversity changed in two streams.Bokermannohyla nanuzaeseemed to have a niche contraction in the presence ofBokermannohyla martinsi, but this only happened during the dry season. Microhabitat requirements during the wet season may be closely linked to similar reproductive needs that probably represent a strong selective pressure, forcing niche overlap. [ABSTRACT FROM PUBLISHER]

Niche theory suggests differential use of shared resources facilitates coexistence of species in a community. In this study we used the faecal stable isotope analysis with observations along transect lines perpendicular to the Pendjari River. This was to examine seasonal habitat features and diet partitioning between two sympatric bovid species waterbuck (Kobus ellipsiprymnus) and western kob (Kobus kob) in the Pendjari Biosphere Reserve. In support of niche partition hypothesis, diets of western kob and waterbuck diverged significantly along both faecal selection axes (δ13C and δ15N) during the resource-limited period of the dry season as opposed to wet season when there is resource abundance. Western kob and waterbuck resource partitioning does not occur only on the basis of diet segregation but also some habitat variables play an important role in the coexisting system. Findings support the niche partition hypothesis, where morphologically, ecologically and closely related sympatric species segregate at least in one of the niche dimensions to allow coexistence. The two bovid species were observed to diverge largely along distance to water source gradient. The results provided empirical evidence that habitat features acts as an additional dimension over which herbivores partition resources. [ABSTRACT FROM AUTHOR]

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This article reports on a study on the effects of bruchid beetle infestation on Acacia trees in the Negev desert and the Arava Valley in Israel. The study also analyzed the life histories of four bruchid beetles developing on three Acacia tree species. The seed beetles include the Acacia raddiana, Acacia gerrardi, and the Acacia tortilis. All of these species were observed to lay eggs readily on Acacia seeds where upon hatching, the larva burrows into the seed to feed.

The eumycetozoan genus Ceratiomyxa appears to have a cosmopolitan distribution, although two of the three macroscopic species within the genus have been reported only from tropical regions of the world. In theory these two tropical species might be expected to display more narrow niches than their cosmopolitan counterpart due to their specialization for tropical environments. However ecological data documenting niche separation in eumycetozoans are largely lacking. As part of several investigations carried out in the neotropics the ecology of the three macroscopic species of Ceratiomyxa was studied. The results from in situ measurements of environmental factors associated with their fructifications reveal a clear separation of niches between the two tropical species, which might be an indication of resource partitioning within the genus. As expected in theory the cosmopolitan C. fruticulosa shows the broadest niche of the three species. Moreover the niche overlap value between C. morchella and C. sphaerosperma along with results from a multivariate CDA analysis seem to indicate that these two species are more specialized than C. fruticulosa. [ABSTRACT FROM AUTHOR]

In an Alpine area, scat analysis and marking activity were used to assess the feeding habits, habitat preference and the degree of overlap of trophic niche and habitat use in sympatric carnivores: the red fox (n = 133 faecal samples), the badger (n = 177), the pine and the stone marten (Martes sp., n = 382). Fruits were the main trophic resource for all species. The diet of martens differed from those of the red fox and badger by means of a higher consumption of garbage and non-Rosaceae fruits. The red fox preyed on more lagomorphs and roe deer and relied almost exclusively on two fruit species, rose-hips and whitebeam berries. Badgers ate few invertebrates, with cultivated fruits and pine seeds forming the bulk of their diet. On the whole, trophic niche overlap was kept low by the exploitation of different species of berries and mammals and, secondly, by seasonal differences in the use of same items by the three carnivores. Badger trophic niche overlapped to a wider extent than those of the other two predators in summer, when fruit availability is higher. Foxes used all habitats according to their availability, except for villages, which were avoided. Badgers used mainly open habitats, particularly Alpine meadows, avoiding villages and mixed woods. Martens selected the habitats avoided by the other two predators and avoided all the others. The narrow range of habitat used by martens and diet evidence suggest that, within the context of interspecific competition, they could play the role of sub-ordinate species, segregating in fox-free urban environments. [ABSTRACT FROM AUTHOR]

Stomach samples of minke whale ( Balaenoptera acutorostrata ) and cod ( Gadus morhua ) were collected on the northeastern parts of the Finnmark coast, northern Norway, in 1998 and 1999 to investigate prey preference, niche overlap and niche width for the two species. A survey to estimate prey abundance was also conducted. Prey preference, niche overlap and niche width were described using Manly's alpha (α), Pianka's index (O jk ) and Levin's index (B), respectively. The diet of cod consisted mainly of capelin, deep-water shrimp, gadoids and krill. The smallest cod (≤64 cm length) preferred capelin, whereas the largest cod (>64 cm length) preferred gadoid species, including cod. The minke whale diet consisted mainly of capelin ( Mallotus villosus ), herring ( Clupea harengus ) and krill, and showed a particular preference for herring and capelin. Krill were consumed in large quantities, but did not seem to be a preferred food item for either cod or minke whales. In contrast to cod, which fed very little on herring, the minke whale fed heavily on herring in some areas. The niche widths for both cod and minke whales were relatively low, and the diet overlap between minke whale and cod was low. [ABSTRACT FROM AUTHOR]

Leptodactylus ocellatus ( LO ) and L . labyrinthicus ( LL ) are known to prey on other frogs. Here we compare their food habits based on the analysis of stomach contents and their spatial distribution when in sympatry. LO was found most frequently near stream banks, and LL on the margins of lakes and ponds. LO was found within 10 m of permanent water bodies; LL frequently used ponds far from lakes and rivers. Coleoptera, Formicidae, and Isoptera comprised 52% of the prey types identified in the LO sample, whereas Coleoptera and insect larvae represented 58% of the prey items of LL . Frogs were not frequent in the diet of either species but, in volume, represented the second most important category for LO and the first for LL . LO showed a larger trophic niche breadth than LL . The trophic niche overlap between the two species was 68.3% for percentage of prey items. The present work confirms the relative importance of frogs in the diet of both species. The greater capacity of LL in moving far away from permanent water bodies may generate better opportunities for prey selection and a narrower trophic niche breadth. The large range of prey used by these two species indicates they are generalist/opportunistic feeders. [ABSTRACT FROM AUTHOR]

Several causes have been considered to explain the specialized ant-feeder habits of the bufonids. We analysed the diet and availability of prey items for sympatric Bufo arenarum, Bufo dorbignyi and Odontophrynus americanus living in a grassland of the flooding pampa, Argentina. Frogs and insects were captured once a month with pitfall traps during the 2-year sampling. The frogs were measured and the stomach content was analysed. Odontophrynus americanus ingests Lepidoptera larvae, Coleoptera, Diptera and Homoptera; while both Bufo species not only feed on ants, but also prefer them. Whereas the two Bufo species show high niche overlap, the niche overlapping between both Bufo and Odontophrynus americanus was low. There are significant differences among body size of both Odontophrynus americanus and Bufo arenarum when compared with B. dorbignyi; while there are no differences in body size of O. americanus and B. arenarum. Gape is larger in Odontophrynus americanus than in Bufo dorbignyi and B. arenarum, but it is similar in the two Bufo species. The mean prey size is larger for Odontophrynus americanus, followed by Bufo arenarum and B. dorbignyi. These results would confirm that the bufonids have ant-feeder habits, perhaps due to their small edentate gape that would constitute a morphological constraint that could explain their mirmecophagic habits. [ABSTRACT FROM AUTHOR]

We examined seasonal changes in microhabitat use by the murid rodents Akodon azarae and Calomys laucha in agroecosystems of the former pampa region of Argentina. In summer, trap data showed that both species had low densities and were almost equally distributed between the mature cropfields and their surrounding weedy borders. Analysis of vegetation at the trap sites revealed no selection for microhabitats at the borders, whereas in the cropfields both species shared preferences for covered microhabitats. In contrast, winter data revealed a sharp habitat segregation, being Calomys numerically dominant in post-harvest cropfields and Akodon more abundant in borders. Moreover, there were clear differences in microhabitat selection at the borders, A. azarae occupying the more covered microhabitats and C. laucha the less covered. Breadth and overlap of niches were calculated using principal component analysis, in order to recognize interspecific competition and its influence on community niche space. Available evidence indicates that the structure of this rodent community is strongly influenced by seasonal changes in habitat stucture and rodent abundance. The socially dominant A. azarae retains the best part of the available niche space, a fact becoming more evident under the harsh winter conditions. [ABSTRACT FROM AUTHOR]