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Background Malaria is often persistent in communities surrounded by mosquito breeding habitats. Anopheles gambiae sensu lato exploit a variety of aquatic habitats, but the biotic determinants of its preferences are poorly understood. This study aimed to identify and quantify macroinvertebrates in different habitat types with determined water physico-chemical parameters to establish those preferred by An. gambiae s.l. larvae as well as their predators and competitors. Methods A field survey was conducted in Kibuye and Kayonjo villages located in the vicinity of the River Sezibwa, north-eastern Uganda to identify Anopheline larval habitats shared by aquatic insects. Habitats were geo-recorded and as streams, ponds, temporary pools and roadside ditches. From October to December 2017, random microhabitats/quadrats were selected from each habitat type, their water physico-chemical parameters (electrical conductivity, total dissolved solids, temperature and pH) were measured, and they were sampled for macroinvertebrates using standard dippers. All collected arthropod macroinvertebrates were then morphologically identified to family level and enumerated. Results Principal component analysis showed that the four larval habitat types were characterized by distinct physico-chemical parameter profiles. Ponds and streams had the highest number and diversity of macroinvertebrate insect taxa and sustained few An. gambiae s.l. larvae. Anopheles gambiae s.l. were more common in roadside ditches and particularly abundant in temporary pools which it commonly shared with Dytiscidae (predaceous diving beetles) and Culex spp. Cluster correlation analysis conducted on the abundance of these taxa within quadrats suggested that An. gambiae s.l. and Dytiscidae have the most similar patterns of microhabitat use, followed by Cybaeidae (water spiders). Whilst Culex spp. co-occurred with An. gambiae s.l. in some habitats, there was only partial niche overlap and no clear evidence of competition between the two mosquito taxa. Conclusions Ponds and streams are habitats that host the largest diversity and abundance of aquatic insect taxa. Anopheles gambiae s.l. larvae distinctively preferred temporary pools and roadside ditches, where they were exposed to few predators and no apparent competition by Culex spp. Further studies should aim to test the impact of Dytiscidae and Cybaeidae on An. gambiae s.l. dynamics experimentally. Graphical Abstract

Background Two coexisting species with similar ecological requirements avoid or reduce competition by changing the extent of their use of a given resource. Numerous coexistence mechanisms have been proposed, but species interactions can also be aggressive; thus, generally a subordinate species modifies its realized niche to limit the probability of direct encounters with the dominant species. We studied niche partitioning between two sympatric wild canids in north-eastern Italy: the golden jackal and the red fox, which, based on competition theories, have a high potential for competition. We considered four main niche dimensions: space, habitat, time, and diet. Results We investigated three study areas monitoring target species populations from March 2017 to November 2018 using non-invasive monitoring techniques. Red fox presence was ascertained in every study area, while golden jackal presence was not ascertained in one study area, where we collected data regarding wolf presence. Considering the two target species, we observed partial diet partitioning based on prey size, with the golden jackal mainly feeding on wild ungulates and the red fox mainly feeding on small mammals. The two canids had an extensive temporal overlap along the diel cycle, having both predominant crepuscular and nocturnal activity patterns, but marked spatial partitioning and differential use of habitats. The golden jackal proved to be specialist concerning the habitat dimension, while the red fox resulted completely generalist: the former selected less human-modified habitats and avoided intensively cultivated lands, while the latter was present in all habitats, including intensively cultivated lands. Conclusions The observed partitioning might be due partially to some ecological adaptations (e.g. specialist vs. generalist use of resources) and specific behaviours (e.g. cooperative vs. solitary hunting) and partially to the avoidance response of the red fox aimed at reducing the probability of direct encounters with the golden jackal.

Ecologia trofca y morfologia de Anolis bartschi (Squamata: Dactyloidae) en el Parque Nacional Vinales, Cuba. Se conoce poco sobre la dieta de los anolinos cubanos. La morfologia en lagartos esta directamente relacionada con funciones ecologicas, como estrategias de forrajeo, competencias interespecifcas, o demanda energetica ligada a la reproduccion. Anolis bartschi es un endemico regional, restringido a las alturas carsicas del occidente de Cuba. Aqui ofrecemos datos nuevos sobre la ecologia trofca de esta especie y su relacion con la morfologia de su cabeza. Se capturaron 131 individuos adultos, donde los machos poseen mayor tamano del cuerpo y de la cabeza que las hembras. La mayoria de los individuos tenia presas en el estomago. Los machos consumiran mas presas que las hembras, pero de menor tamano que estas. Se detecto solapamiento trofco en epoca de seca, pero hubo segregamiento trofco en lluvia. Hymenoptera fue la presa mas consumida por ambos sexos. Ademas, las hembras consumieron mas Blattodea y Coleoptera, mientras los machos mas Diptera. Esta especie prefere presas sedentarias en lugar de moviles. Sugerimos que esta especie prefere presas sedentarias a presas moviles. De acuerdo a nuestros datos y las observaciones de campo, A. bartschi es un forrajeador bimodal, aunque se recomiendan futuras investigaciones sobre la variacion temporal (diaria y anual) en la dieta de esta especie para una apropiada clasifcacion sobre su actividad forrajeadora

Horseshoe crabs are living fossils found in Indonesia. This study examined the food habit of horseshoe crabs (Carcinoscorpius rotundicauda and Tachypleus gigas) collected from Balikpapan coastal waters, East Kalimantan. Horseshoe crabs were captured using gill nets and picked by hand along the Balikpapan coast. The width of the prosoma and the body weight of each individual were measured, and the gut contents were analysed to determine the preponderance index, food niche breadth, and niche overlap. Carcinoscorpius rotundicauda prosoma widths ranged from 4.1 to 15.4 cm and those of Tachypleus gigas ranged from 2.8 to 24 cm. Eight food items were found in the gut of the horseshoe crabs, namely: bivalves, gastropods, scaphopoda, polychaetes, echinoderms, crustaceans, leaf litter and others. Based on the preponderance index, gastropods were the main food item of the two horseshoe crab species. In accordance to the food composition the horseshoe crabs inhabiting Balikpapan coastal waters are categorized as benthivores.

Understanding predator-prey relationships is fundamental to develop effective conservation plans. Between 2015 and 2018, we combed 21 transects, each 7km long, searching for Iberian Lynx Lynx pardinus scat within the province of Madrid in central Spain. In order to minimise inherent subjectivity of visual identification as much as possible, we performed a double specific nested polymerase chain reaction (PCR) followed by a primer extension assay addressed to two Iberian Lynx diagnostic single nucleotide polymorphisms. Forty-six scat samples were positively identified as belonging to Iberian Lynx through genetic analysis. From these, we extracted remains of consumed prey, which we determined to the lowest possible taxonomic level, mainly through hair identification. Identified prey was divided into four types: lagomorphs, small mammals, birds, and ungulates. The species’ diet composition was described based on the frequency of occurrence (FO) of each prey and niche breadth, and also compared with prior knowledge of the species using four prior studies as a comparative reference through the calculation of the niche overlap value. The FO of lagomorphs (39%) was the lowest, while the FO of small mammals (54%) was the highest recorded to date. The niche breath (0.36) was higher than recorded in prior studies, but still showing the specialist character of the Iberian Lynx. Niche overlap was low (C = 0.49), showing differences in trophic niche between the population in our study area and the one studied in southern Spain. This indicates that the Iberian Lynx is adept at switching its main prey, an ability that has previously been firmly rejected. It is, however, capable of adapting to alternative prey more often than recorded to date, which could be a behavioural response to the patchy distribution of European Rabbit Oryctolagus cuniculus in the study area.

Migratory birds occupy different geographical areas during breeding and non-breeding periods, and thus different factors may determine their range limits depending on each season. One such factor is the spatial climatic component of the niche, which is widely used to model species distributions, yet the temporal component is often neglected and is generally assumed to be constant. We tested the hypothesis that the climatic niche is conserved between breeding and non-breeding areas in 355 bird species migrating through Eurasian–African flyways. For this, we performed niche overlap analyses and compared niche differences between sister or phylogenetically closely related species, as well as linking the differences to migratory distances. For more than 80% of the species, there was no or very little overlap between their breeding and non-breeding climatic niches. For most closely related species, the degree of overlap of their breeding climatic niches was larger than the overlap observed within each species, but not for their wintering climatic niches, suggesting a phylogenetic conservation of breeding climatic niches. Finally, there was a clear negative relationship between migratory distances and climatic niche overlap within each species. Our results confirmed that the climatic niche of most Eurasian–African migratory species differs between both breeding and non-breeding ranges, suggesting distinctive seasonal climatic requirements. Given these results and the geographically uneven effects of climate change, the impact of global change is likely to have different effects in each seasonal range. Hence, both breeding and non-breeding climatic data need to be considered when using species distribution models., This study was partly funded by the BiodivERsA2012-74 project from the European Commission FP7 to D.R.V. R.P. was supported by an FPU pre-doctoral fellowship from the Spanish Ministry of Education.

Lichens play a key role in natural ecosystems, as they can function as primary producers, recycle minerals and fix nitrogen. Despite their environmental importance, little is known about lichen ecology in Brazil, and especially about how abiotic factors may influence their spatial distribution. In this study, we aimed to verify how the cover and richness of corticolous lichens on Araucaria angustifolia trunks vary between two different habitats (Forest and Grassland). The photoquadrat sampling method was applied to A. angustifolia trunks. The Coral Point Count software with Excel extensions (CPCe) was used to analyze photographs for lichen cover and richness. Additionally, a redundancy analysis was conducted to estimate how five abiotic and two biotic variables affected the spatial distribution of lichens. Twenty-five morphospecies were identified, none of them occurring exclusively in the Grassland habitat. Canopy openness, air humidity and tree trunk rugosity were important parameters influencing lichen distribution; therefore, spatial segregation of growth forms can be explained by environmental selectivity. Foliose lichens require more air humidity, which explains their predominance in the Forest habitat. Canopy openness in Grassland habitat favors fruticose lichens, which depend on factors such as wind for reproduction.

Bark beetles are a natural part of coniferous forests. Dendroctonus mexicanus Hopkins is the most widely distributed and most destructive bark beetle in Mexico, colonizing more than 21 pine species. The objectives of this study were to generate ecological niche models for D. mexicanus and three of its most important host species, to evaluate the overlap of climate suitability of the association Dendroctonus–Pinus, and to determine the possible expansion of the bark beetle. We used meticulously cleaned species occurrence records, 15 bioclimatic variables and ‘kuenm’, an R package that uses Maxent as a modeling algorithm. The Dendroctonus–Pinus ecological niches were compared using ordination methods and the kernel density function. We generated 1392 candidate models, not all were statistically significant (α = 0.05). The response type was quadratic, there is a positive correlation between suitability and precipitation, and negative with temperature, the latter determining climatic suitability of the studied species. Indeed, a single variable (Bio 1) contributed 93.9% to the model (Pinus leiophylla Schl. &amp, Cham). The overlap of suitable areas for Dendroctonus–Pinus is 74.95% (P. leiophylla) and on average of 46.66% in ecological niches. It is observed that D. mexicanus begins to expand towards climates not currently occupied by the studied pine species.

Natural aquatic sites are disappearing worldwide, especially in the Mediterranean region where amphibians are frequently forced to move for reproduction to artificial sites designed for irrigation and cattle watering (i.e., wells, tanks and drinking troughs). In artificial aquatic sites, where resources (space and food) are usually limited, trophic niche information can be particularly useful to infer the suitability of habitats for amphibian conservation especially when more than one species co-occurs. In this paper, we focused on three newt species: The Italian newt (Lissotriton italicus), the Italian smooth newt (Lissotriton vulgaris meridionalis) and the Italian crested newt (Triturus carnifex) inhabiting man-made wells widespread in an area in Central Italy characterized by few available natural aquatic sites. Specifically, we analyzed the trophic spectrum of the species, their interactions and overlap, and discussed the potential role of wells in amphibian conservation. Overall, 550 newt individuals occurring in 16 distinct wells were sampled. The study species consumed similar resources, mainly of aquatic origin, with Diptera larvae and Cladocera representing the most important preys. The high degree of diet overlap observed may be due to site oligotrophy and high availability of small-sized prey, and it does not necessarily lead to competition. Newts had similar narrow niche width values and a generalist feeding pattern with high diversity among individuals. Lissotriton italicus and T. carnifex showed wider niche width in isolation than in syntopy condition, probably as a result of interspecific competition and/or intraguild predation. We showed that artificial aquatic sites are important for newt ecology and conservation since they allow up to three species to cohabit, thus representing a good surrogate of natural habitats. The study wells apparently provided suitable trophic conditions for newts in terms of prey availability and catchability. To date, just a few studies have contributed to a greater understanding of newts&rsquo, diet in artificial aquatic sites and this gap of knowledge has to be filled to clarify their role in amphibian ecology and conservation.

Made available in DSpace on 2021-06-25T11:07:03Z (GMT). No. of bitstreams: 0 Previous issue date: 2021-03-01 Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq) Schweizerischer Nationalfonds zur Förderung der Wissenschaftlichen Forschung Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP) H2020 European Research Council Invasive species can significantly affect native species when their niches are similar. Ecological and morphological similarities between the invasive Australian palm, Archontophoenix cunninghamiana, and the native palm from the Brazilian Atlantic Forest, Euterpe edulis, suggest that they have similar environmental requirements and functional roles (i.e., the function a species performs in an ecosystem). This similarity raises concerns about how the invasive palm could impact the native species in the present and future. We used spatial (species occurrences) and ecological information (frugivory events) to characterize the environmental niche and functional role of the two palms and assess their overlap. In addition, we predicted the potential area of occurrence of each palm within the Brazilian Atlantic Forest under current and future climate conditions.We estimated the environmental conditions used by the invasive plant based on its native distribution only, and based on all areas where the species is able to establish across the globe. We found that the environmental niches of the two palm species overlap up to 39%, which corresponds to 50% of the current geographic distribution of E. edulis in the Atlantic Forest. In the areas where the two species potentially co-occur, the impact of the invasive species on the native should be influenced by the invasive species interactions with frugivores. We found that the frugivory functional role of the two palms was similar (84% overlap) which suggest that A. cunninghamiana might disrupt the seed dispersal of the native palm. However, co-occurrence between the palms may decline with future climate change, as the potentially environmental suitable area for the invasive palm is predicted to decline by 10% to 55%. Evaluating the similarity in both the environmental niche, of the native and global extent, and the functional role of native and invasive plants provides a detailed understanding of the potential impact of invasive species on native species now and in the future. Departamento de Biodiversidade Instituto de Biociências Universidade Estadual Paulista (UNESP) Swiss Federal Research Institute WSL, Zürcherstrasse 111 Programa de Pós-graduação em Ecologia e Evolução Universidade Federal de Goiás Departamento de Botânica e Ecologia Universidade Federal de Mato Grosso (UFMT), Campus Cuiabá Department of Biology University of Miami Departamento de Biodiversidade Instituto de Biociências Universidade Estadual Paulista (UNESP) CNPq: 150319/2017-7 Schweizerischer Nationalfonds zur Förderung der Wissenschaftlichen Forschung: 173342 FAPESP: 2013/22492-2 FAPESP: 2014/01986-0 FAPESP: 2014/04938-6 FAPESP: 2014/504340 FAPESP: 2017/09676-8 CNPq: 300970/2015-3 H2020 European Research Council: 787638

As ocean temperatures rise, sub-Arctic capelin (Mallotus villosus) and sand lance (Ammodytes spp.) have become increasingly abundant in regions of the eastern Canadian Arctic. These fish have a similar trophic role to the keystone polar cod (Boreogadus saida), potentially competing for food resources when co-occurring. To evaluate this, we calculated feeding niche breadth and overlap based on fatty acids and δ15N- and δ13C-derived trophic position and carbon source, among sub-Arctic fish and 10 Arctic fish and invertebrates within low, mid, and high latitudes of the Canadian Arctic. Diverse feeding strategies including benthic Myoxocephalus sp., anadromous and pelagic fish, led to limited feeding niche overlap among species (13% average, range 0–96%). Feeding niche overlap between capelin and sand lance from the low Arctic was generally high (36–93%); while fatty acid niches of these fish overlapped 0–21% with polar cod in the mid and high Arctic, and their isotopic niches overlapped up to 96%. Capelin and sand lance showed 3–8 times broader feeding niches than polar cod. Regarding regional variation, polar cod had similar niche breadth between regions and highly overlapping fatty acid niches. Niche variation for Myoxocephalus sp. and Gammarus spp. between low and high Arctic was likely associated with more diverse sources of primary production in the shallower, more brackish low Arctic. Although regional variation in food availability play an important role defining feeding niches, broader niches and isotopic niche overlap with polar cod indicated a potential ecological advantage for capelin and sand lance over polar cod under climate change.

BackgroundSmall coastal wetlands are vital sites for wintering waterbirds. Identifying important habitats is critical for managing waterbirds effectively. The Vourkari inlet is a small coastal wetland located near the capital Athens, within the most urbanized and industrialized area of Greece. We aimed at identifying the most important habitats for waterbirds at the Vourkari inlet during winter.MethodsData about habitat use and availability were collected for 14 waterbird species and for seven habitat classes. Habitat selection (Manly’s selection ratio), overlap indices (Pianka’s niche overlap index) and null models were calculated.ResultsAll the studied waterbird species selected available habitats nonrandomly. Shallow waters (0–2 m), were used by 13 waterbirds and selected by five waterbirds. Pools and channels were used and selected by 10 species. Mud was used by nine species and selected by six species. Mud with rocky substrate was used by nine species and selected by eight species. Medium (2–4 m) and deep (4–6 m) open water habitats were used by seven species and selected by four species. Halophytic vegetation was used by six species and selected by two species. Several habitats were selected by nationally important populations: mudflat habitats (i.e., mud, mud with rocky substrate and pools and channels) by Common Redshanks (Tringa totanus), halophytic vegetation by Little Egrets (Egretta garzetta), shallow waters by Common Shelducks (Tadorna tadorna) and medium and deep waters by Sandwich Terns (Thalasseus sandvicencis), whilst shallow waters and mudflat habitats were preferred by a possibly internationally important population of Mediterranean Gulls (Ichthyaetus melanocephalus). Although overlap in habitat use between species was generally low, null models indicated habitat sharing and a lack of competition.ConclusionsWaterbirds coexisted in the absence of competition for habitats at Vourkari, where they mostly used and preferred shallow water and mudflats. Small coastal wetlands are numerous, both in Greece and worldwide, therefore our findings would be useful as a basis for comparisons, both temporal at the inlet and spatial with other sites, that would help assess the importance of habitats and improve management strategies to benefit waterbirds, especially in areas with similar Mediterranean-type habitats and climate.

Organisms with multiple biotic attributes may also have conflicting niche determinants, and we assessed whether the realized niche reflects single or multiple biotic attributes. A group of all‐female salamanders found in eastern North America (unisexual salamanders; Ambystoma spp.) embody two potentially competing biotic states: hybridism and obligate reproductive parasitism. In theory, hybrids should occupy areas that are transitional to those used by parental species, parasites must live in syntopy with their hosts, and parasites that engage in ecological competition with hosts should be most successful in habitats that are moderately suitable for hosts. We built niche models for bisexual salamanders (Ambystoma laterale and Ambystoma jeffersonianum), as well as for unisexual Ambystoma that posses nuclear DNA from both of these species. These unisexuals are both phenotypic hybrids and obligate reproductive parasites of the bisexual species. We characterized realized niches predicted for unisexual Ambystoma via a hybrid‐framework model (e.g., using environmental predictors) and a parasite‐framework model (e.g., using host suitability predictors). Model validation using ancillary data permitted evaluation of which biotic state (hybrid vs. parasite) fit the observed patterns of occupancy. The hybrid model conformed strongly with predictions that the unisexual niche would be transitional between A. laterale and A. jeffersonianum bisexuals. Average annual temperatures and terrestrial salamander species richness (a proxy for competition) were particularly descriptive of parental niches and hybrid occupancy of transitional environments. While the parasite model behaved as expected, model validation did not fully corroborate its utility for determining patterns of occupancy. Instead, model selection revealed that the hybrid model was more descriptive of unisexual occurrence than the parasite model. Despite the fundamental importance of reproductive parasitism to the persistence of unisexual Ambystoma, we suggest that hybridism has greater contribution to the realized niche. When species have competing ecological attributes, one primary biotic state may dominate as a determinant of the realized niche.

The understanding of how niche-related traits change during species invasion have prompted what is now known as the niche conservatism principle. Most studies that have tested the niche conservatism principle have focused on the extent to which the species’ climatic niches remain stable in their exotic distribution. However, it is equality important to address how biotic specialization, i.e. resource use, changes during exotic species invasions. Here, we use the widespread European honeybee (Apis mellifera) to understand whether its Grinnelian and Eltonian niches changed in its exotic distribution using tests of abiotic and biotic niche conservatism. We found that both niche domains of the European honeybee remained stable in its exotic distribution, which means that neither the climatic niche nor the biotic specialization showed significant differences between the native and the exotic ranges. Our findings that climatic and resource use are coupled can be explained by A. mellifera’s long history of domestication and the possibility that life history traits (e.g., polyandry) may have shaped this species’ large niche over the course of evolution and therefore facilitated exotic ranges colonization.

International audience; 1. The white-clawed crayfish (Austropotamobius pallipes) is globally endangered due to the impacts of habitat modification and fragmentation, water pollution, climate change, and invasive species, particularly the signal crayfish (Pacifastacus leniusculus). These pressures have caused the decline of A. pallipes populations in Europe, demonstrating the importance of predicting the species' potential distribution under current and future conditions. Focusing on the watercourses of mainland France, we aimed to identify suitable areas for A. pallipes to guide the conservation of current populations and future introduction actions or protection measures.2. We applied ecological niche modelling to model the potential distribution of both A. pallipes and P. leniusculus and identified locations suitable for A. pallipes only. We also assessed the potential distribution of the species under two representative concentration pathway (RCP) scenarios: RCP 2.6 and RCP 8.5, respectively describing low-warming and high-warming conditions.3. We found that A. pallipes and P. leniusculus exploit equivalent niches in France. Despite this, under current conditions, about 5% of the study area simultaneously records a high suitability for A. pallipes and a low suitability for P. leniusculus and is therefore of significant conservation interest. This percentage remains relatively stable under RCP 2.6 for 2050 and 2100, but decreases to 2% under RCP 8.5 for 2100.4. Ecological niche modelling can supply crucial guidance for conservation actions aimed at protecting endangered species at a national scale by identifying sites most suitable for protection and sites where climate change and invasive species constitute a threat.

18 pages, 5 figures, 6 tables, supplementary information https://doi.org/10.1038/s41598-020-74602-y, This work combines state-of-the-art methods (DNA metabarcoding) with classic approaches (visual stomach content characterization and stable isotope analyses of nitrogen (δ15N) and carbon (δ13C)) to investigate the trophic ecology of anchovy (Engraulis encrasicolus) and sardine (Sardina pilchardus) at high taxonomic and spatial resolution in the Western Mediterranean Sea. Gut contents observed are in accordance with the dietary plasticity generally described for anchovy and sardine, suggesting a diet related to the opportunistic ingestion of available prey in a certain area and/or time. Genetic tools also showed modest inter-specific differences regarding ingested species. However, inter-specific and intra-specific differences in ingested prey frequencies and prey biomass reflected a latitudinal signal that could indicate a more effective predation on large prey like krill by anchovy versus sardine, as well as a generalized higher large prey ingestion by both species southwards. In fact, both species presented lower δ15N in the northernmost area. This latitudinal gradient indicates changes in the trophic ecology of anchovy and sardine that coincide with previously described better biological conditions for fish in the southern part of the study area as well as higher landings of both species in recent years, This study was partially funded by the projects PELWEB (ES-PN-2017-CTM 2017-88939-R) and PELCAT (CAT 152CAT00013, TAIS ARP059/19/00005). MEDITS data collection has been co-funded by the EU through the European Maritime and Fisheries Fund (EMFF) within the National Program of collection, management and use of data in the fisheries sector and support for scientific advice regarding the Common Fisheries Policy, With the funding support of the ‘Severo Ochoa Centre of Excellence’ accreditation (CEX2019-000928-S), of the Spanish Research Agency (AEI)

Quantification of niche overlap represents an important topic in several aspects of ecology and conservation biology, although it could be potentially affected by imperfect detection, i.e., failure to detect a species at occupied sites. We investigate the effect of imperfect detection on niche overlap quantification in two arboreal rodents, the edible dormouse (Glis glis) and the hazel dormouse (Muscardinus avellanarius). For both species, we used Generalized Linear Mixed Models (GLMM) to estimate the occurrence probability and Occupancy Models (OM) to calculate occurrence and detection probabilities. By comparing these predictions through niche equivalency and similarity tests, we first hypothesised that methods correcting for imperfect detection (OM) provide a more reliable estimate of niche overlap than traditional presence/ absence methods (GLMM). Furthermore, we hypothesised that GLMM mainly estimate species detectability rather than actual occurrence, and that a low number of sampling replicates provokes an underestimation of species niche by GLMM. Our results highlighted that GLMM-based niche overlap yielded significant outcomes only for the equivalency test, while OM-based niche overlap reported significant outcomes for both niche equivalency and similarity tests. Moreover, GLMM occurrence probabilities and OM detectabilities were not statistically different. Lastly, GLMM predictions based on single sampling replicates were statistically different from the average occurrence probability predicted by GLMM over all replicates. We emphasized how accounting for imperfect detection can improve the statistical significance and interpretability of niche overlap estimates based on occurrence data. Under a habitat management perspective, an accurate quantification of niche overlap may provide useful information to assess the effects of different management practices on species occurrence.

Bird plumage is often very colorful and can communicate the quality of the bearer to conspecifics. These plumage-based signals of quality are composed of multiple pigments (e.g., melanin and carotenoids). Therefore, sex and age classes, which often show marked differences in plumage coloration, may have different dietary needs for the different plumage components and this might promote preferences for different dietary niches at different molting stages. However, no study has addressed the role that changes in niche use play in the expression of multiple component plumage signals in birds. We used stable isotope analysis to test the hypothesis that niche use is related to age and sex and to differently cultured plumage patches, yellow carotenoid-based and black melanin-based, in great tits Parus major. We recorded high niche overlap between plumage patches, although δ15N was higher in black than yellow plumage. Niche overlap was relatively low for age classes and relatively high for sex classes, and age classes showed a contrasting pattern of niche overlap between carotenoid- and melanin-based plumages. Moreover, δ13C, but not δ15N, had a significant negative relationship with carotenoid-based plumage, which was only apparent in juveniles. Taken together, our results demonstrate that niche use had a moderate influence on plumage coloration characteristics of great tit individuals, mostly associated with δ13C rather than with δ15N and with age rather than with sex. Therefore, our study is significant because it confirms the relevance of niche use during ornament production in free-living birds.

Snow may prevent Arctic herbivores from accessing their forage in winter, forcing them to aggregate in the few patches with limited snow. In High Arctic Greenland, Arctic hare and rock ptarmigan often forage in muskox feeding craters. We therefore hypothesized that due to limited availability of forage, the dietary niches of these resident herbivores overlap considerably, and that the overlap increases as winter progresses. To test this, we analyzed fecal samples collected in early and late winter. We used molecular analysis to identify the plant taxa consumed, and stable isotope ratios of carbon and nitrogen to quantify the dietary niche breadth and dietary overlap. The plant taxa found indicated only limited dietary differentiation between the herbivores. As expected, dietary niches exhibited a strong contraction from early to late winter, especially for rock ptarmigan. This may indicate increasing reliance on particular plant resources as winter progresses. In early winter, the diet of rock ptarmigan overlapped slightly with that of muskox and Arctic hare. Contrary to our expectations, no inter-specific dietary niche overlap was observed in late winter. This overall pattern was specifically revealed by combined analysis of molecular data and stable isotope contents. Hence, despite foraging in the same areas and generally feeding on the same plant taxa, the quantitative dietary overlap between the three herbivores was limited. This may be attributable to species-specific consumption rates of plant taxa. Yet, Arctic hare and rock ptarmigan may benefit from muskox opening up the snow pack, thereby allowing them to access the plants.

A positive biodiversity – aboveground biomass relationship is often attributed to the niche complementarity hypothesis. This hypothesis has received much less support when based on functional trait diversity and when tested in complex natural forests. Here, we hypothesized that niche complementarity (high trait diversity) in the understorey and niche overlap (low trait diversity) in the overstorey would drive whole-community aboveground biomass. To test this hypothesis, we used multiple linear regression models to evaluate how functional trait diversity (functional richness, evenness, divergence and dispersion) of overstorey, understorey, and whole-community determine aboveground biomass across 125 plots in a 5-ha subtropical forest of Eastern China. A structural equation model was used to evaluate whether the functional trait diversity of overstorey affects the relationships between understorey functional trait diversity and whole-community aboveground biomass while considering for the effect of environmental factors. We additionally considered the effects of mass ratio (i.e. community-weighted mean of trait values) and stand structural complexity. The strong negative effect of overstorey functional evenness on aboveground biomass provides support to the functional dominance and/or niche overlap rather than niche complementarity effect. The negative effect of overstorey functional evenness on aboveground biomass was also partially mediated by its direct negative effect on understorey functional evenness. The weak positive effect of understorey functional evenness on aboveground biomass provides support to the niche complementarity effect. We conclude that functional evenness of overstorey and understorey strata affect whole-community aboveground biomass differently through opposing mechanisms, regardless of the effects of mass ratio and stand structural complexity.

International audience; The work of Sheppard et al. (Ecol. Lett., 21, 2018, 1395) relies on the strong assumption that isotopic niche is equal to trophic niche. Here I raise three main concerns showing that classic hypotheses built upon trophic niche cannot be directly interpreted in isotopic space. Future studies should always keep isotopic and trophic niches distinct.

Made available in DSpace on 2018-12-11T17:23:37Z (GMT). No. of bitstreams: 0 Previous issue date: 2017-01-01 Protected areas (PAs) are essential for biodiversity conservation, but their coverage is considered inefficient for the preservation of all species. Many species are subdivided into evolutionarily significant units (ESUs) and the effectiveness of PAs in protecting them needs to be investigated. We evaluated the usefulness of the Brazilian PAs network in protecting ESUs of the critically endangered Pithecopus ayeaye through ongoing climate change. This species occurs in a threatened mountaintop ecosystem known as campos rupestres. We used multilocus DNA sequences to delimit geographic clusters, which were further validated as ESUs with a coalescent approach. Ecological niche modeling was used to estimate spatial changes in ESUs' potential distributions, and a gap analysis was carried out to evaluate the effectiveness of the Brazilian PAs network to protect P. ayeaye in the face of climate changes. We tested the niche overlap between ESUs to gain insights for potential management alternatives for the species. Pithecopus ayeaye contains at least three ESUs isolated in distinct mountain regions, and one of them is not protected by any PA. There are no climatic niche differences between the units, and only 4% of the suitable potential area of the species is protected in present and future projections. The current PAs are not effective in preserving the intraspecific diversity of P. ayeaye in its present and future range distributions. The genetic structure of P. ayeaye could represent a typical pattern in campos rupestres endemics, which should be considered for evaluating its conservation status. Programa de Pós-Graduação em Zoologia Instituto de Ciências Biológicas Universidade Federal de Minas Gerais - UFMG Belo Horizonte, Minas Gerais Brasil Programa de Desarrollo Universitario Centro Universitario de Rivera Universidad de la República - UdelaR Rivera Uruguay Laboratório de Herpetologia Departamento de Zoologia Instituto de Biociências de Rio Claro Universidade Estadual Júlio Mesquita Filho - UNESP Rio Claro, São Paulo Brasil Centro de Sensoriamento Remoto Instituto de Geociências Universidade Federal de Minas Gerais - UFMG Belo Horizonte, Minas Gerais Brasil Laboratório de Fauna e Unidades de Conservação Departamento de Engenharia Florestal Faculdade de Tecnologia Universidade de Brasília - UnB Brasília, Distrito Federal Brasil Graduação em Ciências Biológicas Instituto de Ciências Biológicas Universidade Federal de Minas Gerais - UFMG Belo Horizonte, Minas Gerais Brasil Laboratório Sagarana Instituto de Ciências Biológicas e da Saúde Universidade Federal de Viçosa - UFV Florestal, Minas Gerais Brasil

The coexistence of species with similar ecological requirements (food, space, time) has typically drawn attention of researchers because competition for resources is expected to be high. The diet and microhabitat occupation of two morphologically and ecologically similar species of Hylidae (Anura), Dendropsophus microcephalus and Scarthyla vigilans, were analyzed at a locality in north-western Venezuela, with the aim of addressing the potential for space and food competition between them. Diet was estimated through the analysis of stomach contents and microhabitat occupation was estimated through recordings of perch type, height and horizontal distance to water. Thirty-six prey categories (32 families, 4 orders) of arthropods were identified: 30 categories in D. microcephalus and 21 categories in S. vigilans. The most important prey (RII) in D. microcephalus were Agelenidae (11.1%), Tachinidae (9.32%) and Lepidoptera-larvae (7.96%). Gryllidae (14.13%), Cicadidae (9.1%), Cicadellidae (8.3%) and Delphacidae (8.02%) were the most important in S. vigilans. Diet overlap was relatively low (0.32). Both species have relatively generalist diets. Both species occupied the same type of perches (leaves and stems of Dicotyledons and Monocotyledons) and heights (average: S. vigilans, 24 ± 16.2 cm; D. microcephalus, 22.7 ± 9.5 cm). The potential for space competition is high if perches are limited and food competition is expected to be low. RESUMEN La coexistencia de especies con requerimientos ecológicos similares (alimento, espacio, tiempo) típicamente ha atraído a los investigadores porque se espera que la competencia por recursos sea alta. La dieta y la ocupación de microhábitat de dos especies morfológica y ecológicamente similares de Hylidae (Anura) se analizaron en una localidad al noroeste de Venezuela, con el objetivo de evaluar el potencial para competencia entre ellas. La dieta se estimó a través del análisis de los contenidos estomacales y la ocupación del microhábitat por medio de registros del tipo y altura de la percha y la distancia horizontal al agua. Se identificaron 36 categorías de presa (32 familias, 4 órdenes); 30 en D. microcephalus y 21 en S. vigilans. Las presas más importantes (RII) en D. microcephalus fueron Agelenidae (11,1%), Tachinidae (9,32%) y Lepidoptera-larva (7,96%). Gryllidae (14,13%), Cicadidae (9,1%), Cicadellidae (8,3%) and Delphacidae (8,02%) fueron las más importantes en S. vigilans. Ambas especies tienen dietas relativamente generalistas. La superposición de las dietas fue relativamente baja (0,32). Ambas especies ocuparon el mismo tipo de perchas (hojas y tallos de dicotiledóneas y monocotiledóneas) a las mismas alturas. El potencial para la competencia por espacio es alto si las perchas fuesen escasas, pero se espera que la competencia por el alimento sea baja.

Made available in DSpace on 2018-12-11T16:46:09Z (GMT). No. of bitstreams: 0 Previous issue date: 2017-07-03 Sediment characteristics, especially grain size, are usually considered the most important variables affecting Uca distribution, 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 affecting Uca species 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 to Uca distribution 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. thayeri and U. 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. Graduate Program in Ecology Department of Animal Biology State University of Campinas–SP Laboratory of Ecology and Animal Behavior UNESP–São Paulo State University Bioscience Institute Laboratory of Ecology and Animal Behavior UNESP–São Paulo State University Bioscience Institute

8 pages, 4 figures, 3 tables, 1 appendix.-- This is CMLRE contribution number 73, It is necessary to understand the resource partitioning among species, to describe the functioning of deep sea marine ecosystems. Functional morphology is an effective approach to understand and compare taxonomic units with different phenotypic characteristics related to swimming and foraging. In this study, our main objective was to delineate the functional traits with a view to determine the discrimination level and degree of functional niche overlap among seven common species inhabiting deep-sea waters in south-eastern Arabian Sea. Results indicated significant differences in the functional traits between species providing a low functional niche overlap. Although, the ecological and biological information of fishes were scarce, we demonstrated that functional analyses are effective to extrapolate the prey preferences, sizes and detection and propulsion efficiencies for their feeding and swimming strategies. Our study supports the hypothesis that in some environments with a limitation of resources, species coexisting is due to high resource partitioning. The present work is a first attempt to compare the morpho-functional characteristics and niche partitioning in the deep-sea fish assemblages from the Indian waters., The financial and logistical support from the CMLRE (MoES), is appreciatively acknowledged

The distribution of mangroves is influenced by the environment. We aimed to understand the ecological adaptability of various mangrove species within the range of the exotic species, Sonneratia apetala Buch.‐Ham., in Dongzhai Harbor, Hainan Island, China. We used three niche breadth indexes (Simpson, Levins, and Shannon–Weiner) and two niche overlap indexes (Pianka and Levins) to quantitatively determine the niche characteristics of nine mangrove species. The results showed that the order of the niche breadth values of mangrove species was as follows: Aegiceras corniculatum (Linn.) Blanco > Kandelia obovata Sheue et al. > Bruguiera gymnorrhiza (L.) Poir. > Avicennia marina (Forsk.) Vierh. Hailanci > S. apetala > S. caseolaris (L.) Engl. > Rhizophora stylosa Griff > Ceriops tagal (Perr.) C. B. Rob. > B. sexangula (Lour.) Poir. Pearson correlation analysis revealed that the niche breadth of each population was significantly correlated with the importance value of the population in the whole sample (R1 = R2 = 0.771, R3 = 0.644, p, Experts have different opinions on whether Sonneratia apetala is defined as an invasive species. In this paper, we investigated the growth and succession of S. apetala, which was introduced to China for many years to determine whether the S. apetala would pose a threat to the survival of the local species according the niche theory. The results obtained in this study will provide a theoretical basis for further elucidating the interspecific relationships among exotic and native mangrove species and for the rational utilization of S. apetala.

Synergistic and antagonistic interactions in multi-species populations - such as resource sharing and competition - result in remarkably diverse behaviors in populations of interacting cells, such as in soil or human microbiomes, or clonal competition in cancer. The degree of inter- and intra-specific interaction can often be quantified through the notion of an ecological "niche". Typically, weakly interacting species that occupy largely distinct niches result in stable mixed populations, while strong interactions and competition for the same niche results in rapid extinctions of some species and fixations of others. We investigate the transition of a deterministically stable mixed population to a stochasticity-induced fixation as a function of the niche overlap between the two species. We also investigate the effect of the niche overlap on the population stability with respect to external invasions. Our results have important implications for a number of experimental systems., 32 pages, 12 figures

© The Author(s)., In order to prevent future biological invasions, it is crucial to know non-native species distributions. We evaluated the potential global distribution of Azolla filiculoides, a free-floating macrophyte native to the Americas by using species distribution models and niche equivalency tests to analyze the degree of niche overlap between the native and invaded ranges of the species. The models were projected under two future emission scenarios, three global circulation models and two time periods. Our results indicate a possible niche shift between the distribution ranges of the species, indicating that A. filiculoides can adapt to novel environmental conditions derived from climatic differences during the invasion process. Our models also show that the future potential distribution of A. filiculoides will decrease globally, although the species could colonize new vulnerable regions where it is currently absent. We highlight that species occurrence records in the invaded area are necessary to generate accurate models, which will, in turn, improve our ability to predict potential invasion risk areas.

International audience; Dolphins of the genus Stenella occur in pelagic waters of both tropical and warm-temperate oceans. Three species, the Atlantic spotted dolphin (Stenella frontalis), the pantropical spotted dolphin (S. attenuata), and the spinner dolphin (S. longirostris) are abundant worldwide, but in the Caribbean Basin they have been poorly studied and information on their distribution patterns is scarce. Specifically, in Colombia’s remote Seaflower Biosphere Reserve (SFBR) S. attenuata has been reported occasionally, but S. frontalis and S. longirostris have never been recorded before. To address this information gap, an ecological niche modeling approach was used to determine the potential distribution patterns of these three dolphin species in the region. Records of these species for the Caribbean Basin were compiled, including both published and unpublished data. Environmental information, including bathymetry, bathymetric slope, distance to shore, sea surface temperature, sea surface salinity, and chlorophyll-a concentration was gathered from public databases (MARSPEC and Bio-ORACLE) in raster format. The maximum entropy algorithm (Maxent) for modeling species’ geographic distributions with presence-only data was used. After filtering the data, 210 records of S. attenuata, 204 of S. frontalis, and 80 of S. longirostris were used to run models. The best configuration for each model was chosen based on the ΔAICc criterion. For all three species, the final ecological niche models returned AUC test values higher than 0.8, indicating satisfactory model performance. The resulting potential distribution maps suggested that areas closest to continental shorelines of the Caribbean Basin and surrounding islands had the highest environmental suitability for all species (>70%). All models reported high environmental suitability for S. attenuata and S. longirostris in the SFBR, mainly in the southernmost part surrounding San Andrés and Providence Archipelago. Assessment of niche overlap from the predictions of species distributions using the similarity statistic and pairwise map overlap indicated that S. frontalis and S. longirostris had niches slightly more similar in comparison to S. attenuata. As this was a first effort to fill a gap in our understanding of the distribution of species in the genus Stenella in the Caribbean Basin, further studies are necessary using both niche modeling and biological/ecological approaches.

The desert locust is an agricultural pest that is able to switch from a harmless solitarious stage, during recession periods, to swarms of gregarious individuals that disperse long distances and affect areas from western Africa to India during outbreak periods. Large outbreaks have been recorded through centuries, and the Food and Agriculture Organization keeps a long-term, large-scale monitoring survey database in the area. However, there is also a much less known subspecies that occupies a limited area in Southern Africa. We used large-scale climatic and occurrence data of the solitarious phase of each subspecies during recession periods to understand whether both subspecies climatic niches differ from each other, what is the current potential geographical distribution of each subspecies, and how climate change is likely to shift their potential distribution with respect to current conditions. We evaluated whether subspecies are significantly specialized along available climate gradients by using null models of background climatic differences within and between southern and northern ranges and applying niche similarity and niche equivalency tests. The results point to climatic niche conservatism between the two clades. We complemented this analysis with species distribution modeling to characterize current solitarious distributions and forecast potential recession range shifts under two extreme climate change scenarios at the 2050 and 2090 time horizon. Projections suggest that, at a global scale, the northern clade could contract its solitarious recession range, while the southern clade is likely to expand its recession range. However, local expansions were also predicted in the northern clade, in particular in southern and northern margins of the current geographical distribution. In conclusion, monitoring and management practices should remain in place in northern Africa, while in Southern Africa the potential for the subspecies to pose a threat in the future should be investigated more closely.

International audience; In the Gulf of Guinea, bigeye tuna (Thunnus obesus; BET) and yellowfin tuna (Thunnus albacares; YFT) are an important part of commercial fisheries and play a prominent ecological role as top predators. Using fatty acid profiles and carbon and nitrogen stable isotopes, we examined their trophic niche partitioning in this understudied region. Trophic niche overlap was high (> 70%), similar to percentages in other ocean basins. BET occupied a higher trophic position than YFT and fed on deeper prey (high delta N-15 values and high proportions of monounsaturated fatty acids). The trophic position of YFT decreased slightly in the last 15 years (delta N-15 values decreased by similar to 0.5 parts per thousand), suggesting a change in epipelagic communities, as observed in the eastern Pacific Ocean. Ontogenic changes were limited to BET. For both species, the dietary proportion of the diatom marker 20:5(n-3) increased in the seasonal upwelling area, highlighting the influence of seasonal habitat on the diet of tuna. The relatively lipid-rich muscle (similar to 6% dry mass) of Atlantic tropical tuna suggests a richer diet in this region than that of Indian Ocean tropical tuna and (or) differences in energy allocation strategies.

The objective of this work was to estimate an index of the relative biomass per species, in a medium to large-sized mammal community, as well as to determine how the introduced wild boar (Sus scrofa) fits into this index, and to verify if the occupancy of sites by domestic dogs interferes with those of wild boars and how much the periods of dogs’ activity overlap those of wild boars. The biomass/effort index was measured for each native mammal species and for the introduced wild boar, in two surveyed farms in Brazil’s Western Atlantic Forest range, through the use of camera trappings that were also used to verify if dogs and wild boar overlap in space and activity time. Wild boars seem to dominate the community, just a few years after their presence was first recorded in the region. Surprisingly, several native endangered mammal species persist in the highly modified landscape of the studied areas, but their population trends are still unknown. Wild boars and dogs generally occupy the same areas; however, they do not overlap in activity time, which is an indicative that it is unlikely that the dogs can effectively protect the crops. Resumo: O objetivo deste trabalho foi estimar um índice de biomassa relativa por espécie, em uma comunidade de mamíferos de médio a grande porte, assim como determinar como o javali (Sus scrofa) invasor se ajusta a esse índice, e verificar se a ocupação de locais por cães interfere na ocupação por javalis e quanto o período de atividade dos cães se sobrepõe ao do javali. O índice de biomassa/esforço foi medido para cada espécie de mamífero nativo e também para o javali invasor, em duas fazendas em área de Mata Atlântica do Oeste do Brasil, por meio de armadilhas fotográficas, que também foram usadas para estimar a sobreposição espacial e o período de atividade de cães e javalis. Os javalis parecem dominar a comunidade de mamíferos, poucos anos depois que sua presença na região foi registrada. Surpreendentemente, várias espécies ameaçadas de mamíferos nativos ainda persistem na paisagem altamente modificada das áreas estudadas, porém suas tendências populacionais são ainda desconhecidas. Javalis e cães ocupam em geral as mesmas áreas; no entanto, não se sobrepõem no período de atividade, o que é indicativo de que é improvável que os cães possam efetivamente proteger os cultivos.

Made available in DSpace on 2021-06-25T10:30:28Z (GMT). No. of bitstreams: 0 Previous issue date: 2021-06-01 Ecological Niche Modelling (ENM) is a tool widely used in ecology to determine environmental conditions and the potential distribution of species. In this article we assess the potential distribution, tolerance limits and similarity niche of macroalgae epiphytes and hosts from the Cuba marine shelf. Using different methods (BIOCLIM, Gower, Maxent and SVM) we have modelled the niche for each species. The final prediction map of distribution was made using the ensemble prediction technique. The similarity of ENMs was quantified by Schoener D and Hellinger I distance. The predictive power of all models was reasonable, since the values of the area under the curve (AUC) were greater than 0.9. The host macroalgae most closely related to the spatial distribution pattern of potential abundance of epiphytic macroalgae are Stypopodium zonale (Kendall correlation, r2 = 0.886) and Digenea simplex (Kendall correlation, r2 = 0.777). Environmental variables that contributed mostly (30 %) to the ecological niche models were: the average maximum salinity per year (35.5−36 PSU); the average minimum flow velocity per year (0.2 m·s−1) and the average minimum light at ground level per year (10−60 E·m−2·yr−1). The results show that epiphytic macroalgae and their most common hosts are generalist species (niche width 0.8) with high overlap in their niche (Schoener D > 0.7; Hellinger I distance = I > 0.6). Departamento de Biología y Geografía Universidad de Oriente Patricio Lumumba s/n Santiago de Cuba Instituto de Biociências Departamento de Biociências Laboratório de Análise e Síntese em Biodiversidade Universidade Estadual Paulista (UNESP), Av. 24-A, 1515, Bela Vista Centro de Investigaciones Marinas Universidad de La Habana, Calle 16, No. 114, e/ 1ra y 3ra, Miramar Pennine Water Group University of Sheffield, Sir Frederick Mappin Building, Mappin Street Instituto Universitario de Investigación Marina (INMAR) Universidad de Cádiz (Campus Universitario de Puerto Real, Puerto Real Instituto de Biociências Departamento de Biociências Laboratório de Análise e Síntese em Biodiversidade Universidade Estadual Paulista (UNESP), Av. 24-A, 1515, Bela Vista

Conservation managers and policy makers are often confronted with a challenging dilemma of devising suitable strategies to maintain agricultural productivity while conserving endemic species that at the early stages of becoming pests of agricultural crops. Identification of environmental factors conducive to species range expansion for forecasting species distribution patterns will play a central role in devising management strategies to minimize the conflict between the agricultural productivity and biodiversity conservation. Here, we present results of a study that predicts the distribution of Indrella ampulla, a snail endemic to the Western Ghats biodiversity hotspot, which is becoming a pest in cardamom (Ellettaria cardamomum) plantations. We determined the distribution patterns and niche overlap between I. ampulla and Ellettaria cardamomum using maximum entropy (MaxEnt) niche modeling techniques under current and future (2020–2080) climatic scenarios. The results showed that climatic (precipitation of coldest quarter and isothermality) and soil (cation exchange capacity of soil [CEC]) parameters are major factors that determine the distribution of I. ampulla in Western Ghats. The model predicted cardamom cultivation areas in southern Western Ghats are highly sensitive to invasion of I. ampulla under both present and future climatic conditions. While the land area in the central Western Ghats is predicted to become unsuitable for I. ampulla and Ellettaria cardamomum in future, we found 71% of the Western Ghats land area is suitable for Ellettaria cardamomum cultivation and 45% suitable for I. ampulla, with an overlap of 35% between two species. The resulting distribution maps are invaluable for policy makers and conservation managers to design and implement management strategies minimizing the conflicts to sustain agricultural productivity while maintaining biodiversity in the region.

We analyzed the abundance, distribution and niche overlap of species (Pianka's Ojk index) in tenebrionid beetle communities inhabiting different biotopes in Tyrrhenian and Adriatic sand dunes. The rank abundance distribution of the different species has the form of a geometric series in both communities as predicted by the niche preemption hypothesis for communities in harsh environments. Mean niche overlap values did not deviate significantly from null expectations, which indicates random interspecific interactions. These results, coupled with evidence of species habitat preferences, led us to conclude that the community organization of tenebrionid species inhabiting coastal dunes is determined more by habitat preferences than interspecific competition.

Studies on resource sharing and partitioning generally consider species that occur in the same habitat. However, subsidies between linked habitats, such as streams and riparian zones, create potential for competition between populations which never directly interact. Evidence suggests that the abundance of riparian consumers declines after fish invasion and a subsequent increase in resource sharing of emerging insects. However, diet overlap has not been investigated. Here, we examine the trophic niche of native fish, invasive fish, and native spiders in South Africa using stable isotope analysis. We compared spider abundance and diet at upstream fishless and downstream fish sites and quantified niche overlap with invasive and native fish. Spider abundance was consistently higher at upstream fishless sites compared with paired downstream fish sites, suggesting that the fish reduced aquatic resource availability to riparian consumers. Spiders incorporated more aquatic than terrestrial insects in their diet, with aquatic insects accounting for 45–90% of spider mass. In three of four invaded trout rivers, we found that the average proportion of aquatic resources in web‐building spider diet was higher at fishless sites compared to fish sites. The probability of web‐building and ground spiders overlapping into the trophic niche of invasive brown and rainbow trout was as high as 26 and 51%, respectively. In contrast, the probability of spiders overlapping into the trophic niche of native fish was always less than 5%. Our results suggest that spiders share resources with invasive fish. In contrast, spiders had a low probability of trophic overlap with native fish indicating that the traits of invaders may be important in determining their influence on ecosystem subsidies. We have added to the growing body of evidence that invaders can have cross‐ecosystem impacts and demonstrated that this can be due to niche overlap.

In this study we investigated the group of floral resources that support bee populations from a bee assemblage in a savanna, and the way in which bee species use these food resources, with an emphasis on the breadth and overlap of trophic niches. The interactions between 75 species of bees and 62 species of plants visited to obtain floral resources were recorded on a Brazilian savanna site. The bee species explored a diverse set of plant species, but concentrated the collection of resources in a few plant species. The distribution of the samples over a long period favored a robust characterization of the food niche of the bee populations. Byrsonima sericea, Serjania faveolata, and Stigmaphyllon paralias were the plant species with the highest number of links with bees. In general, the trophic niche overlap was low, with 75% of pairs of bee species having a niche overlap (NO) less than 0.33. Only four pairs showed high overlap (NO>0.70) and all cases were related to the exploitation of floral resources provided by B. sericea, a key resource for the maintenance of the local bee fauna, an oil and pollen provider.

Theoretical and empirical studies have addressed predator-prey relationships, but the relevance of individual prey species, prey species richness and environment on the niche and the distribution of specialist predators have been scarcely tested with a macroecological approach. Here we aim to analyze the niche and spatial distribution of the Magellanic woodpecker (MWP; Campephilus magellanicus), a specialist predator, analyzing the relative importance of its individual prey species, prey species richness and environmental factors. We modeled the niches of the MWP and its five most important long-horned beetle prey species, quantifying their similarity in spatial distribution and niche. Then we evaluated the relative importance of single prey species and prey species richness on the potential distribution of the MWP, which showed a high degree of overlap with the niche and spatial distribution of three prey species. MWP models with each of these three prey species had a better fit than the model with prey species richness, and contributed more than environmental variables. These results suggest that MWP responds to particular prey items rather than prey species richness. These findings highlight the usefulness of ecological niche models to identify behavioral traits, being potentially replicable in other types of interactions such as competition, mutualism, parasitism, and pollination.

Meliponinae eusocial bees are among the most important pollinators in the Neotropics and their beekeeping has been growing as both recreational and economic activity. Information on the pollen preferences and niche overlap among species coexisting in the same location is still scarce. This study focused on the use of pollen resources by three native species of Meliponinae in the Atlantic Forest, Melipona quadrifasciata quadrifasciata (Lepeletier 1836), Scaptotrigona depilis (Moure 1942), and Tetragonisca angustula (Latreille 1811), at two different sites. The use of pollen resources was evaluated from reserves inside hives collected monthly between February 2015 and January 2016. It was also estimated the Mean Minimal Distance (Dm) traveled by the bees to obtain pollen. The bees differed regarding the diversity of pollen types, Dm, and proportion of pollen from different plant life-form. Local factor promoted differences only for Dm. M. q. quadrifasciata foraged a low diversity of pollen species and traveled greater distances with a higher proportion of trees plus palm species. Tetragonisca angustula foraged a higher diversity of pollen and flew shorter distances with a lower proportion of trees and palms. The species factor predominates over the local factor in the clustering pattern, based on pollen profile similarity. Meliponinae eusocial bees are among the most important pollinators in the Neotropics and their beekeeping has been growing as both recreational and economic activity. Information on the pollen preferences and niche overlap among species coexisting in the same location is still scarce. This study focused on the use of pollen resources by three native species of Meliponinae in the Atlantic Forest, Melipona quadrifasciata quadrifasciata (Lepeletier 1836), Scaptotrigona depilis (Moure 1942), and Tetragonisca angustula (Latreille 1811), at two different sites. The use of pollen resources was evaluated from reserves inside hives collected monthly between February 2015 and January 2016. It was also estimated the Mean Minimal Distance (Dm) traveled by the bees to obtain pollen. The bees differed regarding the diversity of pollen types, Dm, and proportion of pollen from different plant life-form. Local factor promoted differences only for Dm. M. q. quadrifasciata foraged a low diversity of pollen species and traveled greater distances with a higher proportion of trees plus palm species. Tetragonisca angustula foraged a higher diversity of pollen and flew shorter distances with a lower proportion of trees and palms. The species factor predominates over the local factor in the clustering pattern, based on pollen profile similarity.

Understanding how functional traits distributed across ecological scales as well as environmental gradients are central issues of trait-based assembly processes. However, whether environmental filters act on individuals or species mean traits remains poorly tested. Here, we measured four functional traits – shoot height, specific leaf area, lamina thickness, and leaf dry mass content – of 4432 individuals from 30 submersed macrophyte species across 26 lakes in south China, covering a broad nutrient gradient. We partitioned trait variances into four nested ecological scales (i.e., region, community, species, individual) and assessed how the internal and external filters structured the submersed macrophyte community, either through acting on individual or on species mean traits, and how these processes related to nutrient enrichment. For the four tested traits, 13–60% of trait variability occurred within species (individual level), while 35–86% occurred among species (species level), followed by community and regional level. Species turnover contributed most to the community-wide variance along the nutrient gradient caused considerable intraspecific variations of shoot height. We found significant strong internal filtering effects on the submersed macrophyte community, which increased towards higher nutrient levels. The external filtering effects were only observed at individual level, with lower shoot height, specific leaf area, and leaf dry mass content than expected at low nutrient levels, and lower lamina thickness than expected at high nutrient levels. Our study provides new insight into the assembly processes by showing that niche overlap (i.e., intraspecific interaction) and niche differentiation (i.e., interspecific interaction) can simultaneously occur in different functional traits, both potentially promoting local species diversity. We conclude that an individual trait-based approach can help to detect assembly processes within and among lakes.

To provide a scientific basis and technical support for agroforestry management practices, such as interrow configuration and soil water and fertilizer management, a stratified excavation method was performed both to explore the fine-root spatial distribution and niche differentiation and to quantify the below-ground interspecific competition status of 3-, 5-, and 7-year-old apple (Malus pumila M.)–soybean (Glycine max L. Merr.) intercropping systems and monocropping systems. The fine roots of older trees occupied a larger soil space and had both a greater fine-root biomass density (FRMD) and a greater ability to reduce the FRMD of soybean, but this ability decreased with the distance from the apple tree row. Similarly, the FRMD of apple trees was also adversely affected by soybean plants, but this effect gradually increased with a decrease in tree age or with the distance from the tree row. Compared with that of the 3- and 5-year-old monocropped apple trees, the FRMD of the 3- and 5-year-old intercropped apple trees increased in the 40–100 cm and 60–100 cm soil layers, respectively. However, compared with that of the 7-year-old apple and soybean monocropping systems, the FRMD of the 7-year-old intercropped apple trees and soybean plants decreased in each soil layer. Compared with that of the corresponding monocropped systems, the fine-root vertical barycenter (FRVB) of the intercropped apple trees displaced deeper soil and that of the intercropped soybean plants displaced shallower soil. Furthermore, the FRVB of both intercropped apple trees and intercropped soybean plants displaced shallower soil with increasing tree age. Intense below-ground interspecific competition in the 3-, 5-, and 7-year-old apple–soybean intercropping systems occurred in the 0–40 cm soil layer at distances of 0.5–0.9, 0.5–1.3, and 0.5–1.7 m from the apple tree row, respectively.

Two dimensions of the ecological niche (diet and habitat) of a snake assemblage from an endemic rich area in east-central Argentina, the Sierras de Ventania mountain chain, were analyzed. Field data collection was performed in 15-week study periods between 2010 and 2014. Snakes were hand-captured using transect surveys. Field observations on diet were analyzed together with stomach content data from museum specimens. Our results supported the partitioning of the snake assemblage by both habitat use and diet into at least three functional groups: species restricted to microhabitats under rocks and with a diet composed exclusively of ants (Epictia australis); species found mostly in stream microhabitats and feeding mainly upon anurans (Erythrolamprus poecilogyrus and Lygophis elegantissimus); and species found mostly in grassland microhabitats, with specialized diets of terrestrial prey items (Philodryas patagoniensis and Bothrops alternatus). Consistent with previous work, diet was more important than habitat in explaining ecological niche partitioning of this snake assemblage. Our results showed that high overlap values of microhabitat use were compensated by low overlap values of the trophic niche dimension, thus matching the traditional complementary niches hypothesis., Facultad de Ciencias Naturales y Museo, Instituto de Limnología "Dr. Raúl A. Ringuelet"

Polar cod (Boreogadus saida) is one of the most studied Arctic marine fishes given its circumpolar distribution and centralised role in the Arctic marine food web. In contrast, relatively little is known about two other Arctic Gadidae: saffron cod (Eleginus gracilis) and Greenland cod (Gadus ogac). Climate change is expected to have an effect on sea ice-associated species, such as polar cod, but due to our lack of knowledge of other arctic gadid species it remains unclear how climate change will impact them and their interactions within the arctic marine ecosystem. Here, we explored the ecology of three Arctic Gadidae that co-occur in the Canadian Beaufort Sea. Stable isotope (SI) (niche overlap) and fatty acid (FA) (correspondence analysis and linear discriminant analysis) biomarkers were used to assess among- and within-species differences and trophic niche. Despite the close habitat proximity of saffron cod and polar cod while on the shelf, trophic niche characterisation revealed only a marginal overlap. Marginal niche overlaps also occurred for the two coastal species with similar diets, saffron cod and Greenland cod, likely reflecting regional-scale differences between two habitats. Within-species, polar cod collected from three habitats (shelf, upper- and lower-slope habitats) were not differentiated likely due to the movement of individuals between habitats. In contrast, Greenland cod had a narrow trophic niche and differentiation occurred between the two collection sites. The comparison of trophic niches defined by stable isotope and fatty acid proved a promising tool for new insights into the ecology of Arctic fishes.

International audience; Closely related syntopic species have been shown to avoid competition by differentiating in the type of food they process. This can be achieved by changes in size or in the masticatory apparatus that produce modifications in bite force. The wood mouse (Apodemus sylvaticus (Linnaeus, 1758)) and Western Mediterranean mouse (Mus spretus Lataste, 1883) are two murid rodent species found in syntopy in the south of France. We measured bite force in wild specimens of both species to test for differences in performance. Despite its greater body mass, the wood mouse showed only slightly higher bite force than the Western Mediterranean mouse. We found no clear sexual dimorphism in either species; however, among the males of the Western Mediterranean mouse, two groups appeared in terms of bite force. This bite force difference may correspond to a hierarchical organization of these males. Overall, it seems that both species have similar bite forces and accordingly overlap in the resources they use. Other factors may exist that create a niche differentiation between the wood mouse and the Western Mediterranean mouse. Another explanation may be a great abundance of food, which would cancel competition for this resource in these species.; Il a été démontré que les espèces proches vivant en syntopie évitent la compétition en différenciant le type de nourriture qu’elles utilisent. Cela peut être permis par des changements de taille ou dans l’appareil masticateur à l’origine de différences dans la force de morsure. Le mulot sylvestre (Apodemus sylvaticus (Linnaeus, 1758)) et la souris d’Afrique du nord (Mus spretus Lataste, 1883) sont deux espèces de rongeurs muridés vivant en syntopie dans le sud de la France. Nous avons mesuré la force de morsure chez des spécimens sauvages des deux espèces pour voir s’il existe des différences de performance. Bien que le mulot sylvestre soit plus gros, sa force de morsure n’est que légèrement plus grande que celle de la souris d’Afrique du nord. Nous n’avons pas détecté de dimorphisme sexuel marqué au sein des deux espèces. Cependant, parmi les souris d’Afrique du nord mâles, deux groupes se distinguent en ce qui concerne la force de morsure, ce qui pourrait refléter une organisation hiérarchique de ces mâles. En général, les deux espèces ont des forces de morsures similaires et, par conséquent, sont en capacité d’accéder aux mêmes ressources alimentaires. D’autres facteurs pourraient être à l’origine d’une différenciation des niches entre le mulot sylvestre et la souris d’Afrique du nord. Une autre explication pourrait être la présence de nourriture en abondance, qui supprimerait la compétition entre les deux espèces.

In this paper, we determined diet composition, reproductive periodicity and fecundity of Astyanax intermedius in a headwater stream of a State Park of an Atlantic rainforest. We also evaluated the influence of rainfall, water temperature and fish size on niche width and niche overlap. Sampling was conducted monthly throughout one year in the Ribeirão Grande stream, southeastern Brazil. Diet consisted of 31 food items with equal contribution of allochthonous and autochthonous items. Females were larger than males, and the mean sizes at first maturation were 4.44 cm and 3.92 cm, respectively. Based on 212 pairs of mature ovaries, the number of oocytes per female ranged from 538 to 6,727 (mean = 2,688.7). Niche width and niche overlap were not related to rainfall nor water temperature and only niche width increased with fish size, suggesting that as fish grow, more items are included in diet. Our results suggested that A. intermedius fit as a typical opportunistic strategist which may explain the prevalence of this species in several isolated headwater basins of vegetated Atlantic forested streams where food resources are abundant and distributed throughout the year. RESUMO Neste trabalho nós determinamos a composição da dieta, periodicidade reprodutiva e fecundidade de Astyanax intermedius em um riacho de cabeceira de um Parque Estadual de Mata Atlântica. Avaliamos também a influência da chuva, temperatura da água e tamanho do peixe na amplitude e sobreposição de nicho. As amostragens foram realizadas mensalmente ao longo de um ano no riacho Ribeirão Grande, sudeste do Brasil. A dieta consistiu de 31 itens, com igual contribuição de itens alóctones e autóctones. As fêmeas foram maiores do que os machos e os comprimentos médios de primeira maturação foram de 4,44 cm e 3,92 cm, respectivamente. Com base nos 212 pares de ovários analisados, o número de ovócitos por fêmea variou de 538 a 6727 (média = 2688,7). A amplitude e a sobreposição de nicho não foram relacionadas à chuva e temperatura da água, e somente a amplitude de nicho aumentou com o tamanho do peixe, sugerindo que conforme o crescimento, mais itens são incluídos na dieta. Nossos resultados sugerem que A. intermedius apresenta um comportamento típico de espécie oportunista, o que pode explicar a prevalência desta espécie em diversos riachos de cabeceiras isolados de Mata Atlântica onde os recursos alimentares são abundantes e distribuídos ao longo do ano.

Adaptation to different thermal environments has the potential to cause evolutionary changes that are sufficient to drive ecological speciation. Here, we examine whether climate‐based niche divergence in lizards of the Plestiodon skiltonianus species complex is consistent with the outcomes of such a process. Previous work on this group shows that a mechanical sexual barrier has evolved between species that differ mainly in body size and that the barrier may be a by‐product of selection for increased body size in lineages that have invaded xeric environments; however, baseline information on niche divergence among members of the group is lacking. We quantified the climatic niche using mechanistic physiological and correlative niche models and then estimated niche differences among species using ordination techniques and tests of niche overlap and equivalency. Our results show that the thermal niches of size‐divergent, reproductively isolated morphospecies are significantly differentiated and that precipitation may have been as important as temperature in causing increased shifts in body size in xeric habitats. While these findings alone do not demonstrate thermal adaptation or identify the cause of speciation, their integration with earlier genetic and behavioral studies provides a useful test of phenotype–environment associations that further support the case for ecological speciation in these lizards.