Environmental Niche

The Merodon aureus species group (Diptera: Syrphidae: Eristalinae) comprises a number of different sub-groups and species complexes. In this study we focus on resolving the taxonomic status of the entity previously identified as M. cinereus B, here identified as M. atratus species complex. We used an integrative approach based on morphological descriptions, combined with supporting characters that were obtained from molecular analyses of the mitochondrial cytochrome c oxidase I gene as well as from geometric morphometry of wing and surstylus shapes and environmental niche comparisons. All applied data and methods distinguished and supported three morphologically cryptic species: M. atratus stat. nov., M. virgatus sp. nov. and M. balkanicus sp. nov., which constitute the M. atratus species complex. We present an identification key for the sub-groups and species complexes of the M. aureus species group occurring in Europe, describe the taxa and discuss the utility of the applied metho...

The contribution of deterministic and stochastic processes to species coexistence is widely debated. With the introduction of powerful statistical techniques, we can now better characterise different sources of uncertainty when quantifying niche differentiation. The theoretical literature on the effect of stochasticity on coexistence, however, is often ignored by field ecologists because of its technical nature and difficulties in its application. In this review, we examine how different sources of variability in population dynamics contribute ...

Efficient management and prevention of species invasions requires accurate prediction of where species of concern can arrive and persist. Species distribution models provide one way to identify potentially suitable habitat by developing the relationship between climate variables and species occurrence data. However, these models when applied to freshwater invasions are complicated by two factors. The first is that the range expansions that typically occur as part of the invasion process violate standard species distribution model assumptions of data stationarity. Second, predicting potential range of freshwater aquatic species is complicated by the reliance on terrestrial climate measurements to develop occurrence relationships for species that occur in aquatic environments. To overcome these obstacles, we combined a recently developed algorithm for species distribution modeling—range bagging—with newly available aquatic habitat‐specific information from the North American Great Lak...

Aim: The Expansion-Contraction model has been used to explain the responses of species to climatic changes. During periods of unfavourable climatic conditions, species retreat to refugia from where they may later expand. This paper focuses on the palaeoecology of red deer over the past 54 ka across Europe and the Urals, to reveal patterns of change in their range and explore the role of environmental conditions in determining their distribution. Location: Europe and western Asia to 63°E. Taxon: Red deer (Cervus elaphus). Methods: We collected 984 records of radiocarbon-dated red deer subfossils from the Late Pleistocene and the Holocene, including 93 original dates. For each deer sample we compiled climatic and biome type data for the corresponding time intervals. Results: During the last 54 ka changes in red deer range in Europe and the Urals were asynchronous and differed between western and eastern Europe and western Asia due to different environmental conditions in those regions. The range of suitable areas for deer during the Last Glacial Maximum (LGM) was larger than previously thought and covered vast regions not only in southern but also in western and eastern Europe. Throughout the period investigated the majority of specimens inhabited forests in the temperate climatic zone. The contribution of forests in deer localities significantly decreased during the last 4 ka, due to deforestation of Europe caused by humans. Mean January temperature was the main limiting factor for species distribution. Over 90% of the samples were found in areas where mean January temperature was above −10°C. Main conclusions: Red deer response to climatic oscillations are in agreement with the Expansion-Contraction model but in contradiction to the statement of only the southernmost LGM refugia of the species. During the last 54 ka red deer occurred mostly in forests of the temperate climatic zone.

The MarHa Life project coordinated by the Office Français de la Biodiversité aims at restoring and/or maintaining the good ecological status of natural marine habitats in France. As part of this project, my mission was to statistically model the spatial distribution of zostera seagrass beds (Zostera marina and Zostera noltei) along the French Atlantic and English Channel coastline. A first objective was to assess results sensitivity to the modelling approach and in particular to the type of model used (GLM, RF, BRT) so as to characterize the performance of the method and to identify the best-suited models. Then, using the selected models, a second objective was to predict the potential spatial distribution of these two species along the French Atlantic-Channel coast, and to describe their environmental niche. Finally, the last objective was to model the potential impacts of different climate change scenarios on the potential habitat of these two species. Using an ensemble of Random ...

The establishment of cattle ranches throughout the world has prompted the release of dung beetles as biological control agents that reduce pasture fouling and control dung‐breeding flies. One of these beetles, Digitonthophagus gazella (Fabricius) (Coleoptera: Scarabaeidae), that is native to southeast Africa, has been introduced into the Americas, Australia, and New Zealand. Distribution records for this species have been used to develop climate models of potential future establishment. Recent studies, however, identify D. gazella as a complex of seven species. Taking into account this revision, and the clear identification of the records belonging to the actual D. gazella, we developed environmental models to identify factors that have contributed to the establishment of this species across regions and habitats. We compared the environmental conditions of D. gazella in its native range against those in the regions where the species has or has not established. Our results indicate t...

Seed source regions drive fitness differences in invasive macrophytes PREMISE: Worldwide, ecosystems are threatened by global changes, including biological invasions. Invasive species arriving in novel environments experience new climatic conditions that can affect their successful establishment. Determining the response of functional traits and fitness components of invasive populations from contrasting environments can provide a useful framework to assess species responses to climate change and the variability of these responses among source populations. Much research on macrophytes has focused on establishment from clonal fragments; however, colonization from sexual propagules has rarely been studied. Our objective was to compare trait responses of plants generated from sexual propagules sourced from three climatic regions but grown under common environmental conditions, using L. peploides subsp. montevidensis as a model taxon. METHODS: We grew seedlings to reproductive stage in experimental mesocosms under a mediterranean California (MCA) climate from seeds collected in oceanic France (OFR), mediterranean France (MFR), and MCA. RESULTS: Seed source region was a major factor influencing differences among invasive plants recruiting from sexual propagules of L. peploides subsp. montevidensis. Trait responses of young individual recruits from MCA and OFR, sourced from geographically distant and climatically distinct source regions, were the most different. The MCA individuals accumulated more biomass, flowered earlier, and had higher leaf N concentrations than the OFR plants. Those from MFR had intermediate profiles. CONCLUSIONS: By showing that the closer a seedling is from its parental climate, the better it performs, this study provides new insights to the understanding of colonization of invasive plant species and informs its management under novel and changing environmental conditions. KEY WORDS biological invasions; climate change; creeping water primrose; environmental niche; invasion ecology; MERRAclim bioclimatic variables; Onagraceae; plant traits; sexual reproduction.

AimLocally abundant species are usually widespread, and this pattern has been related to properties of the niches and traits of species. However, such explanations fail to account for the potential of traits to determine species niches and often overlook statistical artefacts. Here, we examine how trait distinctiveness determines the abilities of species to exploit either common habitats (niche position) or a range of habitats (niche breadth) and how niche position and breadth, in turn, affect abundance and occupancy. We also examine how statistical artefacts moderate these relationships.LocationSixteen sites in the Neotropics.Time period1993–2014.Major taxa studiedAquatic invertebrates from tank bromeliads.MethodsWe measured the environmental niche position and breadth of each species and calculated its trait distinctiveness as the average trait difference from all other species at each site. Then, we used a combination of structural equation models and a meta‐analytical approach t...

Efficient management and prevention of species invasions requires accurate prediction of where species of concern can arrive and persist. Species distribution models provide one way to identify potentially suitable habitat by developing the relationship between climate variables and species occurrence data. However, these models when applied to freshwater invasions are complicated by two factors. The first is that the range expansions that typically occur as part of the invasion process violate standard species distribution model assumptions of data stationarity. Second, predicting potential range of freshwater aquatic species is complicated by the reliance on terrestrial climate measurements to develop occurrence relationships for species that occur in aquatic environments. To overcome these obstacles, we combined a recently developed algorithm for species distribution modeling—range bagging—with newly available aquatic habitat‐specific information from the North American Great Lak...

In this study, the taxonomic diversity of the Xylodon raduloides species complex (Hymenochaetales, Basidiomycota) is examined. Specimens were studied using an integrative taxonomic approach that includes molecular phylogenetic and morphological analyses, and environmental niche comparisons. Four different species were found inside the Xylodon raduloides complex, with a biogeographic distribution pattern bound by geographic regions: Europe, North America, Patagonia, and Australia-New Zealand. Molecular, morphological, and environmental evidences delimit two lineages within this complex: a Northern Hemisphere clade with longer basidiospores and wider ranges in temperature and precipitation tolerance, and a Southern Hemisphere clade with smaller and more spherical basidiospores, and an isothermal and more humid climate preference. The integrative taxonomic approach used in this study demonstrates congruence between data sets and shows how morphological and environmental characteristics contribute to the differentiation of fungal species complexes. By combining various sources of taxonomic information, three new species are described: Xylodon laurentianus, X. novozelandicus, and X. patagonicus.

Les recherches, menées dans le cadre du projet de recherche ANR « Mammouths », sur « la disparition de la steppe à mammouths : relations hommes/environnements à la fin du Pléniglaciaire en Europe orientale », font l'objet de plusieurs contributions dont une partie est réunie dans ce numéro sous l'intitulé « Hommes et environnements au Paléolithique supérieur en Ukraine continentale et en Crimée », dans la revue L'anthropologie.

European Union forest policy calls for closer-to-nature forest management, but natural disturbances and forest succession are ecological phenomena that are difficult to characterize and integrate into sustainable forest management practices. Therefore, the aim of this study is to explore the adaptive properties of Lithuania’s hemi-boreal forest ecosystems. To accomplish this, we first reviewed (i) the potential natural forest communities, (ii) the successional dynamics, and (iii) adaptive strategies of forest trees, and second, we synthesised the adaptive relationships using these three reviews. The results firstly identified that Lithuania’s potential natural forests are broadly divided into two climatically based zonal formations: (i) mesophytic and hygromesophytic coniferous and broadleaved forests and (ii) mesophytic deciduous broadleaved and coniferous-broadleaved forests. Secondly, the review of successional dynamics showed that each tree species can be categorised into variou...

Aim: The Expansion-Contraction model has been used to explain the responses of species to climatic changes. During periods of unfavourable climatic conditions, species retreat to refugia from where they may later expand. This paper focuses on the palaeoecology of red deer over the past 54 ka across Europe and the Urals, to reveal patterns of change in their range and explore the role of environmental conditions in determining their distribution. Location: Europe and western Asia to 63°E. Taxon: Red deer (Cervus elaphus). Methods: We collected 984 records of radiocarbon-dated red deer subfossils from the Late Pleistocene and the Holocene, including 93 original dates. For each deer sample we compiled climatic and biome type data for the corresponding time intervals. Results: During the last 54 ka changes in red deer range in Europe and the Urals were asynchronous and differed between western and eastern Europe and western Asia due to different environmental conditions in those regions. The range of suitable areas for deer during the Last Glacial Maximum (LGM) was larger than previously thought and covered vast regions not only in southern but also in western and eastern Europe. Throughout the period investigated the majority of specimens inhabited forests in the temperate climatic zone. The contribution of forests in deer localities significantly decreased during the last 4 ka, due to deforestation of Europe caused by humans. Mean January temperature was the main limiting factor for species distribution. Over 90% of the samples were found in areas where mean January temperature was above −10°C. Main conclusions: Red deer response to climatic oscillations are in agreement with the Expansion-Contraction model but in contradiction to the statement of only the southernmost LGM refugia of the species. During the last 54 ka red deer occurred mostly in forests of the temperate climatic zone.

The MarHa Life project coordinated by the Office Français de la Biodiversité aims at restoring and/or maintaining the good ecological status of natural marine habitats in France. As part of this project, my mission was to statistically model the spatial distribution of zostera seagrass beds (Zostera marina and Zostera noltei) along the French Atlantic and English Channel coastline. A first objective was to assess results sensitivity to the modelling approach and in particular to the type of model used (GLM, RF, BRT) so as to characterize the performance of the method and to identify the best-suited models. Then, using the selected models, a second objective was to predict the potential spatial distribution of these two species along the French Atlantic-Channel coast, and to describe their environmental niche. Finally, the last objective was to model the potential impacts of different climate change scenarios on the potential habitat of these two species. Using an ensemble of Random ...

The urgency of predicting future impacts of environmental change on vulnerable populations is advancing the development of spatially explicit habitat models. Continental-scale climate and microclimate layers are now widely available. However, most terrestrial organisms exist within microclimate spaces that are very small, relative to the spatial resolution of those layers. We examined the effects of multi-resolution, multi-extent topographic and climate inputs on the accuracy of hourly soil temperature predictions for a small island, generated at a very high spatial resolution (<1 m 2) using the mechanistic microclimate model in NicheMapR. Achieving an accuracy comparable to lower-resolution, continentalscale microclimate layers (within about 2-3°C of observed values) required the use of daily weather data as well as high resolution topographic layers (elevation, slope, aspect, horizon angles), while inclusion of site-specific soil properties did not markedly improve predictions. Our results suggest that large-extent microclimate layers may not provide accurate estimates of microclimate conditions when the spatial extent of a habitat or other area of interest is similar to or smaller than the spatial resolution of the layers themselves. Thus, effort in sourcing model inputs should be focused on obtaining high resolution terrain data, e.g., via LiDAR or photogrammetry, and local weather information rather than in situ sampling of microclimate characteristics.

Aim: The Expansion-Contraction model has been used to explain the responses of species to climatic changes. During periods of unfavourable climatic conditions, species retreat to refugia from where they may later expand. This paper focuses on the palaeoecology of red deer over the past 54 ka across Europe and the Urals, to reveal patterns of change in their range and explore the role of environmental conditions in determining their distribution. Location: Europe and western Asia to 63°E. Taxon: Red deer (Cervus elaphus). Methods: We collected 984 records of radiocarbon-dated red deer subfossils from the Late Pleistocene and the Holocene, including 93 original dates. For each deer sample we compiled climatic and biome type data for the corresponding time intervals. Results: During the last 54 ka changes in red deer range in Europe and the Urals were asynchronous and differed between western and eastern Europe and western Asia due to different environmental conditions in those regions. The range of suitable areas for deer during the Last Glacial Maximum (LGM) was larger than previously thought and covered vast regions not only in southern but also in western and eastern Europe. Throughout the period investigated the majority of specimens inhabited forests in the temperate climatic zone. The contribution of forests in deer localities significantly decreased during the last 4 ka, due to deforestation of Europe caused by humans. Mean January temperature was the main limiting factor for species distribution. Over 90% of the samples were found in areas where mean January temperature was above −10°C. Main conclusions: Red deer response to climatic oscillations are in agreement with the Expansion-Contraction model but in contradiction to the statement of only the southernmost LGM refugia of the species. During the last 54 ka red deer occurred mostly in forests of the temperate climatic zone.

Aim Analyses of spatial overlap in species distributions are frequently used to test a range of ecological and evolutionary hypotheses, from the role of competition in community assembly to the geography of speciation. Most studies quantify overlap at one spatial resolution. Here we explore the effects of measuring spatial and niche overlap patterns for the same clade (Banksia) at multiple resolutions. Location Australia. Methods We quantify overlap among species using broad overlap of species range polygons, proximity of occurrence points and co-occurrence within small survey plots. We compare overlap patterns with null models using age-range correlations and the frequency of sympatric sister species. We then use similar methods to examine patterns of overlap in environmental niche dimensions. Results Banksia species show a wide range of overlap values based on range polygons and point proximities, but very low levels of co-occurrence at the local scale. Intercepts of age-range correlations point to higher levels of overlap among recently diverged species than expected. However, comparing the frequency of sympatric sister species with an evolutionary null model supports a prevailing allopatric mode of speciation. In many cases, niche overlap between species exceeds that expected from phylogenetic relatedness or spatial overlap alone. Main conclusions Patterns of broad geographical overlap among Banksia species support a predominantly allopatric mode of speciation, combined with post-speciation range drift. There is more evidence for niche conservatism than for rapid niche divergence among closely related species. This pattern is consistent with broad-scale geomorphic and landscape complexity as a driver of plant speciation in southwest Australia. It is less consistent with finer-scale mechanisms of species divergence such as fire mosaics, or with ecological divergence in sympatry. Analysis of species overlap patterns at different resolutions is a useful approach for revealing the multiple ecological and historical factors that influence species distributions.

Species invasions are severe drivers of environmental change. Invasive plants may affect soil dynamics, interactions, and ecosystem functioning, leading to environmental and economic losses. Although species invasion success has been explained by niche conservatism, recent studies have demonstrated that niche shifts may also play a key role in this process. In this study, we tested whether niche shift has occurred during the range expansion of the Yellow Bells, Tecoma stans (Bignoniaceae) and predicted its global risk of invasion. We used Reciprocal Ecological Niche Models techniques and multivariate analyses to test our hypothesis and produce a worldwide invasion risk for this species. Niche spaces of African, Australian, and American exotic populations did not differ substantially from the natural one, although the reciprocal models we fitted for exotic and native occurrences poorly predicted each other. The predictions of the models indicated that T. stans is prone to invade new areas where it has not been recorded yet. Given its competitive abilities, preventive programs in prone-to-be-invaded areas are highly recommended.

The introduction of cattle into different regions of the world has led to dung beetle relocation programs to reduce pasture fouling and to control dung-breeding flies. One of these beetles, Digitonthophagus gazella (Fabricius, 1787) (Coleoptera: Scarabaeidae), is native to southeast Africa and has been introduced into the Americas, Australia, and New Zealand. Distribution records for this species have been used by several authors to develop climate models of potential future establishment. Recent studies, however, identify D. gazella as a complex comprised of seven species. Taking into account this revision, we developed climate models to identify factors contributing to the ability of this species to establish in many different regions. We compared the climatic conditions of D. gazella in its origin with climatic conditions where the species has or has not established. In Africa, Central, and South America, our results indicate that D. gazella is absent in regions where it could potentially establish. We speculate that its African distribution is limited due to competitive exclusion. The introduction of D. gazella in Central and South America is relatively recent, such that the full extent of its distribution may yet to be realized. In Australia and North America, D. gazella is present in regions not predicted by the native climatic conditions. This discrepancy may reflect a lack of competitive exclusion, phenotypic plasticity, and (or) genetic adaptation. Our analyses suggest that the species has the ability to adapt to new conditions and a wide range of climatic regions that are extremely different from those in the native region.

Species invasions are severe drivers of environmental change. Invasive plants may affect soil dynamics, interactions, and ecosystem functioning, leading to environmental and economic losses. Although species invasion success has been explained by niche conservatism, recent studies have demonstrated that niche shifts may also play a key role in this process. In this study, we tested whether niche shift has occurred during the range expansion of the Yellow Bells, Tecoma stans (Bignoniaceae) and predicted its global risk of invasion. We used Reciprocal Ecological Niche Models techniques and multivariate analyses to test our hypothesis and produce a worldwide invasion risk for this species. Niche spaces of African, Australian, and American exotic populations did not differ substantially from the natural one, although the reciprocal models we fitted for exotic and native occurrences poorly predicted each other. The predictions of the models indicated that T. stans is prone to invade new areas where it has not been recorded yet. Given its competitive abilities, preventive programs in prone-to-be-invaded areas are highly recommended.

The introduction of cattle into different regions of the world has led to dung beetle relocation programs to reduce pasture fouling and to control dung-breeding flies. One of these beetles, Digitonthophagus gazella (Fabricius, 1787) (Coleoptera: Scarabaeidae), is native to southeast Africa and has been introduced into the Americas, Australia, and New Zealand. Distribution records for this species have been used by several authors to develop climate models of potential future establishment. Recent studies, however, identify D. gazella as a complex comprised of seven species. Taking into account this revision, we developed climate models to identify factors contributing to the ability of this species to establish in many different regions. We compared the climatic conditions of D. gazella in its origin with climatic conditions where the species has or has not established. In Africa, Central, and South America, our results indicate that D. gazella is absent in regions where it could potentially establish. We speculate that its African distribution is limited due to competitive exclusion. The introduction of D. gazella in Central and South America is relatively recent, such that the full extent of its distribution may yet to be realized. In Australia and North America, D. gazella is present in regions not predicted by the native climatic conditions. This discrepancy may reflect a lack of competitive exclusion, phenotypic plasticity, and (or) genetic adaptation. Our analyses suggest that the species has the ability to adapt to new conditions and a wide range of climatic regions that are extremely different from those in the native region.

Cave shrimps of the Typhlatya genus are common and widespread in fresh, brackish and marine groundwater throughout the Yucatan Peninsula (Mexico). These species are ideal models to test niche partitioning within sympatric species in oligotrophic systems. Nevertheless, their food sources remain unidentified, and despite their frequency and functional importance, distribution and abundance patterns of these species within caves have not been fully recognized. Here, we describe the abundance of three Typhlatya species in different temporal and spatial scales, investigate changes in water conditions, and potential sources of carbon as an indication of food origin. Species composition and abundance varied markedly in space and time revealing patterns that differed from one system to another and in relation to environmental parameters. Isotope analysis showed that each species reflects a particular δ13C and Δ14C fingerprint, suggesting they feed in different proportions from the available...

Se abordan los principios biológicos en el proceso de modelado de nicho ecológico, haciendo algunas consideraciones sobre el concepto de nicho ecológico y el área de distribución. Presentamos una compilación y proponemos una clasificación de los algoritmos utilizados en el proceso del modelado de nichos ecológicos. Hacemos énfasis en que cada algoritmo hace una representación del nicho ecológico de la especie y que no existen nichos buenos o malos, sino representaciones diferentes por lo que es indispensable entender cómo funcionan para tener un mejor criterio informado de lo que se está utilizando.

Mycorrhizal symbiosis has been related to the coexistence and community assembly of coexisting orchids in few studies despite their obligate dependence on mycorrhizal partners to establish and survive. In hyper-diverse environments like tropical rain forests, coexistence of epiphytic orchids may be facilitated through mycorrhizal fungal specialization. However, information on the role of orchid mycorrhizal fungi (OMF) in niche differentiation and coexistence of epiphytic orchids is still scarce. In this study, we sought to identify the variation in fungal preferences of four co-occurring epiphytic orchids in a tropical rainforest in Costa Rica by addressing the identity and structure of their endophytic fungal and OMF communities across species and life stages. We show that the endophytic fungal communities are formed mainly of previously-recognized OMF taxa, and that the coexisting orchid species display distinct (OMF) communities while keeping a base of shared fungi. We also found...

Aim: The Expansion-Contraction model has been used to explain the responses of species to climatic changes. During periods of unfavourable climatic conditions, species retreat to refugia from where they may later expand. This paper focuses on the palaeoecology of red deer over the past 54 ka across Europe and the Urals, to reveal patterns of change in their range and explore the role of environmental conditions in determining their distribution. Location: Europe and western Asia to 63°E. Taxon: Red deer (Cervus elaphus). Methods: We collected 984 records of radiocarbon-dated red deer subfossils from the Late Pleistocene and the Holocene, including 93 original dates. For each deer sample we compiled climatic and biome type data for the corresponding time intervals. Results: During the last 54 ka changes in red deer range in Europe and the Urals were asynchronous and differed between western and eastern Europe and western Asia due to different environmental conditions in those regions. The range of suitable areas for deer during the Last Glacial Maximum (LGM) was larger than previously thought and covered vast regions not only in southern but also in western and eastern Europe. Throughout the period investigated the majority of specimens inhabited forests in the temperate climatic zone. The contribution of forests in deer localities significantly decreased during the last 4 ka, due to deforestation of Europe caused by humans. Mean January temperature was the main limiting factor for species distribution. Over 90% of the samples were found in areas where mean January temperature was above −10°C. Main conclusions: Red deer response to climatic oscillations are in agreement with the Expansion-Contraction model but in contradiction to the statement of only the southernmost LGM refugia of the species. During the last 54 ka red deer occurred mostly in forests of the temperate climatic zone.

Aim: Understanding the mechanisms that allow the coexistence of species is key to preserve full ecosystem functioning. In dynamic environments, the study of ecological niches faces the complexity associated to the three dimensionality of the habitat and requires information that reflects such heterogeneity. Within this context, this study intends to identify the segregation mechanisms behind the co-occurrence of five phylogenetically related pelagic birds by applying a functional perspective based on seabirds' vertical ranges and prey availability features such as depth and body size. Location: Bay of Biscay. Methods: Based on the hypothesis that niche differentiation may occur in any of the three dimensions of the marine environment, we (a) identified the biologically meaningful vertical range affecting seabird species, (b) modelled their environmental and trophic niches, (c) estimated an environmental and trophic overlap index for each pairwise species, and (d) developed a conceptual framework with the most plausible segregation hypotheses. Results: The application of the conceptual framework revealed that in this particular area, pelagic birds coexist through environmental and trophic niche partitioning and potentially through vertical segregation, based on the different biologically meaningful vertical ranges we identified for each species. Indeed, some species responded to prey and oceanographic conditions on the surface (10 m), while others responded to the conditions on deeper waters (above the depth of maximum temperature gradient). These different responses could be interpreted as an additional mechanism to reduce competition, although seabirds diving records would be needed to contrast this hypothesis. Main conclusions: Niche differentiation was found to be primarily driven by trophic and environmental niche partitioning, although species were also influenced by conditions on the vertical dimension. Considering all the dimensions of the niche is essential to fully understand how diving seabirds coexist in dynamic systems and provides insights on species' 3D niches that may help advance into their management. This is an open access article under the terms of the Creative Commons Attribution License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited.

Le gisement d'Eliseevichi 1, situé dans le bassin du Dniepr, plus particulièrement dans la vallée de la Desna, a été découvert en 1930 par K.M. Polikarpovich. Il est contemporain des occupations épigravettiennes de la fin de la seconde moitié du Pléniglaciaire supérieur (20 000-14 000 BP). Comme pour les sites de la culture de Mézine (Mézine, Mezhirich, Gontsy, et Dobranitchevka), il a été interprété comme un campement d'habitat de chasseurs spécialisés, principalement pour l'abattage de mammouths laineux, puis d'animaux à fourrure. En outre, les ossements de mammouth auraient été employés pour réaliser de plus grandes structures que dans les sites méziniens, associées à des fosses de stockage, comme à Timonovka I, Yudinovo, Yourevitchi, Suponevo, et Chulatovo. Cependant, il se différencie de tous les autres sites par la présence de pièces en ivoire gravées de motifs en zigzag et de traits linéaires multiples et la présence de www.em-consulte.com

Aim: The Expansion-Contraction model has been used to explain the responses of species to climatic changes. During periods of unfavourable climatic conditions, species retreat to refugia from where they may later expand. This paper focuses on the palaeoecology of red deer over the past 54 ka across Europe and the Urals, to reveal patterns of change in their range and explore the role of environmental conditions in determining their distribution. Location: Europe and western Asia to 63°E. Taxon: Red deer (Cervus elaphus). Methods: We collected 984 records of radiocarbon-dated red deer subfossils from the Late Pleistocene and the Holocene, including 93 original dates. For each deer sample we compiled climatic and biome type data for the corresponding time intervals. Results: During the last 54 ka changes in red deer range in Europe and the Urals were asynchronous and differed between western and eastern Europe and western Asia due to different environmental conditions in those regions. The range of suitable areas for deer during the Last Glacial Maximum (LGM) was larger than previously thought and covered vast regions not only in southern but also in western and eastern Europe. Throughout the period investigated the majority of specimens inhabited forests in the temperate climatic zone. The contribution of forests in deer localities significantly decreased during the last 4 ka, due to deforestation of Europe caused by humans. Mean January temperature was the main limiting factor for species distribution. Over 90% of the samples were found in areas where mean January temperature was above −10°C. Main conclusions: Red deer response to climatic oscillations are in agreement with the Expansion-Contraction model but in contradiction to the statement of only the southernmost LGM refugia of the species. During the last 54 ka red deer occurred mostly in forests of the temperate climatic zone.

The establishment of cattle ranches throughout the world has prompted the release of dung beetles as biological control agents that reduce pasture fouling and control dung-breeding flies. One of these beetles, Digitonthophagus gazella (Fabricius) (Coleoptera: Scarabaeidae), that is native to southeast Africa, has been introduced into the Americas, Australia, and New Zealand. Distribution records for this species have been used to develop climate models of potential future establishment. Recent studies, however, identify D. gazella as a complex of seven species. Taking into account this revision, and the clear identification of the records belonging to the actual D. gazella, we developed environmental models to identify factors that have contributed to the establishment of this species across regions and habitats. We compared the environmental conditions of D. gazella in its native range against those in the regions where the species has or has not established. Our results indicate that D. gazella is still absent in certain parts of Central and South America and parts of Africa where it could potentially establish. We speculate that its distribution in Africa is limited by competitive exclusion. The introduction of D. gazella in America is relatively recent, such that the full extent of its distribution has probably yet to be realized. In Australia and North America, D. gazella is present in regions not predicted according to its native environmental conditions. This discrepancy may reflect a lack of competitive exclusion, phenotypic plasticity, and/or genetic adaptation. Our analyses suggest that the species has the ability to adapt to a wide range of environmental conditions that are extremely different from those in their native region. The species represents a useful case study to indicate that an introduced species may expand its realised niche beyond what is expected based on apparent environmental limits in the species native range.

We propose the beginnings of a general theory of environments, of the parts or regions of space in which organisms live and move. We draw on two sources: on the one hand on recent work on the ontology of space; and on the other hand on work by ecological scientists on concepts such as territory, habitat, and niche.

Higher δ15N values in bone collagen of mammoth (Mammuthus primigenius) compared with coeval large herbivores is a classic trait of the mammoth steppe. An exception applies to the Epigravettian site of Mezhyrich (ca. 18–17.4 ka cal BP) in the central East European plains, where mammoth bones have δ15N values equivalent to or in a lower range than those of horse specimens (Equussp.). We expanded our preliminary dataset to a larger sampling size of mammoth, other large herbivores, and carnivores from contemporaneous and nearby sites of Buzhanka 2, Eliseevichi, and Yudinovo. The unusual low mammoth δ15N values were confirmed at Buzhanka 2 and for some specimens from Eliseevichi, while most individuals from Yudinovo displayed the expected high δ15N values, meaning similar to those of the large canids. The possibility of a contrast in migration pattern is not supported since the δ34S values, a marker of mobility, do not correlate with the δ15N values of mammoth bone collagen. No clear chr...

This paper presents the outline of a formal ontology of contexts. More specifically, it deals with the ontology of ecological contexts (niches, habitats, environments, ambients) and of the relations between organisms, niches, and the spatial regions they occupy. The first part sets out the basic conceptual background. The second part outlines a semi-formal theory which builds upon notions and principles of mereology, topology, and the theory of spatial location.

The history of evolution is a history of development from less to more complex organisms. This growth in complexity of organisms goes hand in hand with a concurrent growth in complexity of environments and of organism-environment relations. It is a concern with this latter aspect of evolutionary development that motivates the present paper. We begin by outlining a theory of organism-environment relations. We then show that the theory can be applied to a range of different sorts of cases, both biological and non-biological, in which objects are lodged or housed within specific environments, or niches. Biological science is interested in types-for example in genotypes, phenotypes, and environment types-in regularities that can serve as the basis for the formulation of laws or general principles. Types, however, can exist only through their corresponding tokens. Our theory of token environments is meant to plug this gap and to provide a first step towards a general theory of causally relevant spatial volumes.

Cave shrimps of the Typhlatya genus are common and widespread in fresh, brackish and marine groundwater throughout the Yucatan Peninsula (Mexico). These species are ideal models to test niche partitioning within sympatric species in oligotrophic systems. Nevertheless, their food sources remain unidentified, and despite their frequency and functional importance, distribution and abundance patterns of these species within caves have not been fully recognized. Here, we describe the abundance of three Typhlatya species in different temporal and spatial scales, investigate changes in water conditions, and potential sources of carbon as an indication of food origin. Species composition and abundance varied markedly in space and time revealing patterns that differed from one system to another and in relation to environmental parameters. Isotope analysis showed that each species reflects a particular δ13C and Δ14C fingerprint, suggesting they feed in different proportions from the available...

Se abordan los principios biológicos en el proceso de modelado de nicho ecológico, haciendo algunas consideraciones sobre el concepto de nicho ecológico y el área de distribución. Presentamos una compilación y proponemos una clasificación de los algoritmos utilizados en el proceso del modelado de nichos ecológicos. Hacemos énfasis en que cada algoritmo hace una representación del nicho ecológico de la especie y que no existen nichos buenos o malos, sino representaciones diferentes por lo que es indispensable entender cómo funcionan para tener un mejor criterio informado de lo que se está utilizando.

Climate change threatens Earth's biodiversity, although its impacts are variable and depend on the capacity of species and ecosystems to cope with the magnitude and speed of change. Natural protected areas (NPAs) constitute potential refugia for species' persistence and for sustaining the provisioning of ecosystem services. Biosphere reserves are NPAs that are less altered by human actions and provide habitat to endemic, threatened or endangered species. Here, we aim to evaluate the threat imposed by climate change on the network of biosphere reserves in Mexico. Focusing on five bioclimatic variables, we computed the climatic spacemeasured as an n-dimensional hypervolume-of 40 NPAs. Increases in temperature are predicted for all NPAs by 2050, whereas decreases in annual rainfall are predicted for 30 NPAs. By 2050, 31 NPAs that provide habitat to 22,866 recorded species are predicted to lose 100% of their baseline climatic space, shifting to completely novel climates. On average, the other nine NPAs are predicted to lose 55.7% (SD = 26.7%) of their baseline climatic space, while 54.5% (SD = 32.5%) of the future climatic space will be novel. Seventeen NPAs may lose climate variability (homogenization), decreasing species' niches. The extent to which non-analogue conditions will remain within the tolerance of species and ecosystems is currently unknown. Finally, we propose a vulnerability index to categorise NPAs based on their loss of existing climatic space, total geographic area, species richness, and uniqueness of species composition, finding los Tuxtlas and Tiburon Ballena as the most and least vulnerable NPAs, respectively.

Some may recall that 42 was a number that kept popping up in some of Douglas Adams' cult comic/ science fiction novels 'whenever one least expected it.' For those unfamiliar with the significance of this number, it is, as revealed by Adams' computer 'Deep Thought', the Ultimate answer to the Ultimate question of Life, the Universe and Everything (cf. BBC Online, 2002). One might say that the ultimate question asked by biogeographers is: what explains spatial patterns in biodiversity? This has been the Holy Grail at least since Alfred Russel Wallace first speculated on global biodiversity patterns almost 125 years ago (Wallace, 1878). Is the ultimate answer something as simple as the fundamental biodiversity number? In his new book, The unified neutral theory of biodiversity and biogeography, Hubbell asserts that this simple parameter can in fact explain most of the observed spatial and temporal patterns found in species abundances wherever one looks. But what about 42? It turns out that this is the fundamental biodiversity number that might describe a typical tropical rain forest system, such as Hubbell found on Barro Colorado Island, Panama. But the sceptic will still ask: can a single number really capture and explain the pattern and process in biodiversity of a particular system or locality? Many ecologists and biogeographers have spun wheels over the last century trying to explain biodiversity patterns at any spatial scale. Michael Palmer listed 120 different explanations that may account for observed patterns in biodiversity (Palmer, 1996). This is certainly a disconcertingly long laundry list of idiosyncratic possibilities. In the last two years, at least four authors have published on the theme of 'the' universal explanation of geographical patterns in biodiversity. Yet conventional wisdom still holds that there will be no simple, universal explanation. Attempts to develop a synthetic perspective have proven elusive or are quickly dismissed by critics. Indeed, Hubbell remarks on the first page of his book that 'the science of biodiversity is not much further along than medicine was in the Middle Ages.' All of this sets the stage for Hubbell's timely book, a scholarly work that is both impressively creative and thought provoking. It is at the same time mathematically rigorous, yet quite readable. Even if one doesn't follow the maths, the written arguments and interpretations are quite clear. This book represents a culmination of the study of neutral community dynamics on which Hubbell first embarked in the late 1970s. The book is not meant to be a full review of the field. Nevertheless, Hubbell has succeeded in the daunting task of providing an overview of the state of the field, and launching a novel theory. Hubbell begins with a road map of his main objectives in the book: (1) to develop a formal theory of neutral ecological drift; (2) to demonstrate its importance in the assembly and dynamics of ecological communities; and (3) to demonstrate its predictive power in biodiversity and biogeography. This chapter pays homage to the legacy of MacArthur and Wilson's theory of island biogeography (MacArthur & Wilson, 1967). It is easy to show that after 35 years, surprisingly little progress has been made in further developing or advancing island biogeography theory. Hubbell is thus motivated to demonstrate that his neutral ecological drift theory has significantly advanced the field. He does acknowledge that both niche-assembly and dispersal-assembly undoubtedly contribute to community structure (and hence local diversity). But the mission of the book is to demonstrate that most of the patterns can be explained by his neutral theory. Critical to accepting Hubbell's line of argument is accepting the two fundamental assumptions of his theory: (1) that communities are 'biotically saturated at all times', that is, 'any increase [or decrease] in the abundance of one species in a community is matched by a simultaneous decrease [or increase] in the abundance of another'; and (2) that all species are neutral entities with the same per capita probabilities of birth, death, and dispersal. It is important to realize that Hubbell is thinking only of communities consisting of 'trophically similar' species, or more specifically, plants. Hubbell's conception of neutral ecological drift is now apparent. Yet, as he readily admits, falsifying a neutral theory is a non-trivial task. The reader is thus faced with evaluating the significance and generality of the theory and its predictions, given these assumptions. Nevertheless, the diversity of evidence Hubbell presents supporting his theory is indeed impressive. The second chapter provides an exceptionally clear, concise review of theories of species abundance patterns-classically: Fisher's log series, Preston's canonical lognormal, and MacArthur's broken stick SPECIAL BOOK REVIEW

This paper presents a novel approach of population genetics together with environmental and biogeographic data leading to inferences for ecological niche modelling. We used hierarchical lineages obtained using the nested cladistic analysis (NCA) of the mitochondrial DNA (mtDNA) haplotypes of the bark beetle species Tomicus destruens, for modelling the distribution by maximum entropy using environmental and host variables along the whole Mediterranean Basin. The identity and similarity tests were checked in the intraspecific lineages (NCA clades and haplotypes) in order to determine a shift or conservatism niche between them. Also, four indices from nine geographical areas in the Mediterranean Basin were calculated to assess the variability of environmental factors shaping the distribution of haplotype diversity on a large geographic scale. The ecological models developed indicate that minority eastern mtDNA lineages of T. destruens differ in their potential ecological niche according to their relation to extreme climatic variables. By contrast, the most widespread western lineages display a close relationship with their Pinus host tree. Also, higher levels of exclusive and endemic haplotypes were predicted in areas with high temperature variability in the Mediterranean wet period. The eastern group niche seems to be included in part of the range of the ecological space of the two major western clades. This result suggests that a niche shift might have started, being still an early relationship with its host tree Pinus brutia. Alternatively, the temperature variability in the wettest period appears to be related to a high proportion of endemic haplotypes of T. destruens, possibly by involving a balance between the length of the flight reproductive period of T. destruens and the status of the host tree vigour and growth stage. This study illustrates a good example of the benefits that ecological niche modelling provides to understand population genetic and phylogeographic patterns.

Cave shrimps of the Typhlatya genus are common and widespread in fresh, brackish and marine groundwater throughout the Yucatan Peninsula (Mexico). These species are ideal models to test niche partitioning within sympatric species in oligotrophic systems. Nevertheless, their food sources remain unidentified, and despite their frequency and functional importance, distribution and abundance patterns of these species within caves have not been fully recognized. Here, we describe the abundance of three Typhlatya species in different temporal and spatial scales, investigate changes in water conditions, and potential sources of carbon as an indication of food origin. Species composition and abundance varied markedly in space and time revealing patterns that differed from one system to another and in relation to environmental parameters. Isotope analysis showed that each species reflects a particular δ13C and Δ14C fingerprint, suggesting they feed in different proportions from the available...

The distribution and abundance of marine organisms are directly or indirectly a function of biotic and abiotic features such as sediment and water properties. In this study we analyzed the spatial and temporal distribution of Callinectes danae in two distinct littoral areas of the northern coast of the State of São Paulo, Brazil and associated them with local geomorphologic features and environmental factors. We collected specimens on a monthly basis, from July 2001 to June 2003, using a fishing boat equipped with double-rig net, in two locations: Ubatuba (UBA) and Caraguatatuba (CAR). Collecting was carried out in seven transects with different depths, which were further subdivided into two regions: bay region (5, 10, 15 and 20 m deep); and inner shelf region (25, 30 and 35 m deep). Samples from different periods and transects differed significantly in abundance. A positive correlation was found between the abundance of C. danae and the following parameters: temperature at the bott...

Climate change threatens Earth's biodiversity, although its impacts are variable and depend on the capacity of species and ecosystems to cope with the magnitude and speed of change. Natural protected areas (NPAs) constitute potential refugia for species' persistence and for sustaining the provisioning of ecosystem services. Biosphere reserves are NPAs that are less altered by human actions and provide habitat to endemic, threatened or endangered species. Here, we aim to evaluate the threat imposed by climate change on the network of biosphere reserves in Mexico. Focusing on five bioclimatic variables, we computed the climatic spacemeasured as an n-dimensional hypervolume-of 40 NPAs. Increases in temperature are predicted for all NPAs by 2050, whereas decreases in annual rainfall are predicted for 30 NPAs. By 2050, 31 NPAs that provide habitat to 22,866 recorded species are predicted to lose 100% of their baseline climatic space, shifting to completely novel climates. On average, the other nine NPAs are predicted to lose 55.7% (SD = 26.7%) of their baseline climatic space, while 54.5% (SD = 32.5%) of the future climatic space will be novel. Seventeen NPAs may lose climate variability (homogenization), decreasing species' niches. The extent to which non-analogue conditions will remain within the tolerance of species and ecosystems is currently unknown. Finally, we propose a vulnerability index to categorise NPAs based on their loss of existing climatic space, total geographic area, species richness, and uniqueness of species composition, finding los Tuxtlas and Tiburon Ballena as the most and least vulnerable NPAs, respectively.