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The suite of factors that drives where and under what conditions a species occurs has become the focus of intense research interest. Three general categories of methods have emerged by which researchers address questions in this area: mechanistic models of species’ requirements in terms of environmental conditions that are based on first principles of biophysics and physiology, correlational models based on environmental associations derived from analyses of geographic occurrences of species, and process-based simulations that estimate occupied distributional areas and associated environments from assumptions about niche dimensions and dispersal abilities. We review strengths and weaknesses of these sets of approaches, and identify significant advantages and disadvantages of each. Rather than identifying one or the other as ‘better,’ we suggest that researchers take great care to use the method best-suited to each specific research question, and be conscious of the weaknesses of any method, such that inappropriate interpretations are avoided.

Despite a broad distribution, general habitat requirements, and a large dispersal potential, bobcats (Lynx rufus) exhibit a genetic division that longitudinally transects central North America. We investigated (1) whether the climate of the Last Glacial Maximum (LGM; 21 kya) isolated bobcats into refugia and also whether the current climate influences gene flow between the segregate populations and (2) whether the geographical patterns in cranial morphology reflect population identity. We created ecological niche models (ENMs) to evaluate climatic suitability and to estimate distributions of the disparate populations under both historical (LGM) and contemporary conditions. We used two-dimensional geometric morphometric methods to evaluate variations in the cranium and mandible. These variations were then regressed across geographical variables to assess morphological differences throughout the range of the bobcat. ENMs projected onto LGM climate provided evidence of refugia during the LGM via increased suitability in the north-west and south-east portions of this species' range. Contemporarily, our models suggest that the Great Plains may be restricting bobcat migration and gene flow, effectively maintaining disparate populations. Morphological analyses identified a significant linear trend in shape variation across latitudinal and longitudinal gradients rather than distinct morphological divergence between lineages. Similar shape variations, however, did converge in approximate locations of assumed refugia. The findings of the present study provide a robust assessment of the biogeographical considerations for the population genetic structure of bobcats.

Background Autochthonous transmission of Borrelia burgdorferi, the primary agent of Lyme disease in dogs and people in North America, commonly occurs in the northeastern United States, including the New York City metropolitan area, a region with a large human and pet population and broadly diverse demographics and habitats. Methods We evaluated results from a specific, C6-based serologic assay performed on 234,633 canine samples to compare evidence of past or current infection with B. burgdorferi (sensu stricto) in dogs to county-wide social and environmental factors, as well as to reported cases of Lyme disease in people. Results The data revealed a wide range of county level percent positive canine test results (1.2–27.3%) and human case reports (0.5–438.7 case reports/100,000 people). Dogs from highly (> 50%) forested areas and counties with lower population density had the highest percent positive test results, at 21.1% and 17.9%, respectively. Canine percent positive tests correlated with population-adjusted human case reports (R2 = 0.48, P < 0.0001), as well as population density, development intensity, temperature, normalized difference vegetation index, and habitat type. Subsequent multiple regression allowed an accurate prediction of infection risk in dogs (R2 = 0.90) but was less accurate at predicting human case reports (R2 = 0.74). Conclusion In areas where Lyme disease is endemic, canine serology continues to provide insight into risk factors for transmission to both dogs and people although some differences in geographic patterns of canine infection and human disease reports are evident. Electronic supplementary material The online version of this article (10.1186/s13071-018-2774-z) contains supplementary material, which is available to authorized users.

International audience; Aim: To examine the combined effect of abiotic and biotic factors on species distri-butions in a marine environment. Specifically, we aim to account for the effects of trophic interactions at broad scales in ecological niche models (ENMs) of sea kraits (Laticauda: Reptilia) by including the potential distribution of food resources as pre-dictor variables.Location: Oceania and Southeast Asia.Methods: First, we outline a simple method to generate biotic interaction variables for ENMs. We then test whether ENMs that include biotic interactions perform bet-ter than ENMs based on abiotic variables only.Results: The models based on biotic interactions (i.e. trophic interactions) and abi-otic variables slightly outperformed the models informed only by abiotic variables. We found a strong relationship between prey species richness and probability of distribution of predator (sea kraits). The models that included potential distributions of prey species as predictor variables showed an increase in proportion of pixels predicted present and a decrease in omission error, compared with models based only on abiotic variables.Main conclusions: Distribution estimates of predator species at broad scales are more accurate if calibration of ENMs includes relevant biotic variables (prey species richness, in this study). Hence, when data are available, biotic variables should be included in ENMs.

Landscapes and their structure are important in shaping the distribution of species and the composition of communities. Since a landscape contains elements that are less permeable to dispersal, species use corridors of habitat suitable to movements that maintain the genetic flow among populations. Corridors have been widely used in conservation biology, but less often to study the connectivity between species’ allopatric ranges. In this study, we analyzed the distribution and connectivity patterns of the Danube Crested Newt (Triturus dobrogicus), a species found in the Danube river basin and whose range is separated by the Carpathian Mountains in two regions, eastern and western. Despite the geographical barrier and clear morphological differentiation between the populations of the two regions, recent genetic analyses suggest maintenance of genetic flow. The aims of our study were (1) to estimate the dispersal ability of the Danube Crested Newt and the connectivity (via corridors) between populations and (2) to identify possible pathways used by the species to cross the Carpathian Mountains barrier. We found that the landscape facilitates a higher population connectivity in the western range than in the eastern range of the species. Moreover, we identified two major migration pathways, along the Iron Gate Canyon and the Timis – Cerna Gap, that may connect all known occurrences from the two regions separated by the Carpathian Mountains. As an alternative dispersal hypothesis, we also discussed the possibility that the Danube Crested Newt is passively dispersed by water, down the Danube river flow direction. Our study provides support for the assertion that even when a species’ distribution is separated in two ranges by a geographical barrier, connectivity between populations via corridors can persist.

According to recent phylogeographical evidence, the common genet (Genetta genetta) and the Egyptian mongoose (Herpestes ichneumon) have dissimilar dispersal histories from Maghreb to south-western Europe. Through comparative ecological niche modelling based on >1100 occurrences, we assessed whether the niche dynamics (i.e. niche shift versus conservatism) of the two species in their European ranges reflected DNA-based demographic scenarios. Sensitivity analyses and projections of climatic niche models from the species' native ranges (Africa and Middle East) to Europe yielded support for (1) partial climatic niche shift in the northern European range of the common genet and (2) climatic niche conservatism in the Egyptian mongoose. Our results were consistent with demographic scenarios that predicted multiple introductions and demographic expansion in the common genet and long-term, stable historical demography in the Egyptian mongoose. Our models further predicted a range expansion of the common genet in north-western France and Italy, and progression of the Egyptian mongoose into Europe from the Near East. Overall, our study suggested a scenario of different niche dynamics in Europe for these two species of African carnivores, supporting the view that historical factors such as dispersal and demographic history may shape niche dynamics and thus distribution potential in colonized ranges. © 2015 The Linnean Society of London, Biological Journal of the Linnean Society, 2015, 114, 737–751.

The distribution of the nine banded armadillo (Dasypus novemcinctus), the only species in the family Dasypodidae found in the USA, has expanded greatly since the species was first recorded in southern Texas in 1849. Currently, the range of D. novemcinctus includes 15 states in the USA. Previous studies on the geographical expansion of this species, based on physiological experiments and distribution surveys, revealed a possible western moisture limit, a northern temperature limit, and potential north-eastward range expansion in the USA. We applied an ecological niche modelling approach and produced a potential distribution map of D. novemcinctus with comparable western (102 °W) and northern (40 °N) limits, and confirmed the possibility of further north-east range expansion to climatically suitable areas in the USA.

Fluvial fishes face increased imperilment from anthropogenic activities, but the specific factors contributing most to range declines are often poorly understood. For example, the range of the fluvial-specialist shoal bass (Micropterus cataractae) continues to decrease, yet how perceived threats have contributed to range loss is largely unknown. We used species distribution models to determine which factors contributed most to shoal bass range loss. We estimated a potential distribution based on natural abiotic factors and a series of currently occupied distributions that incorporated variables characterizing land cover, non-native species, and river fragmentation intensity (no fragmentation, dams only, and dams and large impoundments). We allowed interspecific relationships between non-native congeners and shoal bass to vary across fragmentation intensities. Results from the potential distribution model estimated shoal bass presence throughout much of their native basin, whereas models of currently occupied distribution showed that range loss increased as fragmentation intensified. Response curves from models of currently occupied distribution indicated a potential interaction between fragmentation intensity and the relationship between shoal bass and non-native congeners, wherein non-natives may be favored at the highest fragmentation intensity. Response curves also suggested that100 km of interconnected, free-flowing stream fragments were necessary to support shoal bass presence. Model evaluation, including an independent validation, suggested that models had favorable predictive and discriminative abilities. Similar approaches that use readily available, diverse, geospatial data sets may deliver insights into the biology and conservation needs of other fluvial species facing similar threats.

Of the four species encompassing the genus Pelobates, only two overlap along a narrow contact zone, i.e., Pelobates fuscus and Pelobates syriacus. Our study investigated the shifts in niche similarity of these two closely related species from the Last Interglacial towards the end of the twenty-first century. We computed climatic suitability models using Maxent and projected them onto future and past climates. We used fossil occurrences to test the predictive accuracy of past projections. Niche similarity was assessed between the studied species using Schoener’s D index and a background similarity test. Finally, we evaluated niche differentiation by contrasting the species occurrences using a logistic regression analysis. The ecological niches are slightly extended outside the present geographical ranges in the Caucasus and the Balkans, south for P. fuscus and north and west for P. syriacus, suggesting that their present distribution is not at equilibrium with the climate. The Last Interglacial distribution of P. fuscus included British Isles and broad areas in western, central, and northern Europe, while P. syriacus extended northwards in the Balkans. The validation with fossil records revealed good predictive performance (omission error = 4.1 % for P. fuscus and 16.6 % for P. syriacus). During the Last Glacial Maximum, climatic suitability persisted in refugia in southern Europe, Pannonian Basin, and Caucasus for P. fuscus, and Israel, southern Balkans, and Caucasus for P. syriacus. Present potential distributions revealed a low similarity of species’ ecological niches, comparable with Last Interglacial, but projections towards 2080 revealed a sharp increase.

Past climates experienced by fossil plant species have often been inferred based on the environmental requirements of their evolutionarily nearest living relatives (NLR). Here we have combined paleoclimatic estimation using NLRs with ecolological niche modeling (ENM) and have demonstrated the combined approach by inferring the Eocene environment of Aesculus L. (Hippocastanoideae, Sapindaceae), a genus of woody eudicots with extant species generally preferring temperate climates. Specifically, we applied ENM-NLR to four Eocene floras in which Aesculus fossils are known to occur: McAbee and Princeton (British Columbia), Republic (Washington State), and Spitsbergen (European Arctic Circle). Additionally, we used ENM-NLR to estimate whether paleoenvironmental conditions were suitable for Aesculus at a fifth flora, Copper Basin (Nevada), where the fossil record of the genus is less clear. We generated models for all NLRs in Genetic Algorithm for Rule Set Production using georeferenced data from the Global Biodiversity Information Facility and Bioclim environmental parameters. For each fossil flora, the best models of individual NLRs were summarized into composite community models, which were taken to represent climatically analogous modern communities and used to infer the paleoclimates of the fossil localities. Our results are generally consistent with previous studies that used other methods to estimate paleoclimates and suggest that McAbee, Princeton, Republic, and Spitsbergen had temperate environments. For the Copper Basin flora, our results show ranges of environmental variables that may be too broad for predicting whether Aesculus was present. Our study appears to be the first to combine the NLR approach and ENM to infer paleoclimates.

Conservation of rare or endemic species is a multifaceted matter, especially whenever knowledge gaps in species' distribution and anthropogenic pressures converge. We combined Geographic Information Systems and ecological niche modeling tools with field data to characterize the habitat types used for different behavioral activities and to identify important areas for conservation of a charismatic bird endemic to northeast South America, the Guianan cock-of-the-rock (Rupicola rupicola). Using species' occurrences and climatic, topographic, and remotely sensed vegetation variables we developed potential distribution models at two scales: (1) broad geographic scale (northern South America), based on georeferenced occurrences obtained from literature and natural history museum specimens, and (2) local scale, based on precise occurrences (GPS coordinates) recorded in the field (Caverna do Maroaga Protected Area, Amazonas, Brazil). We identified six priority areas for the conservation of the cock-of-the-rock corresponding to high environmental suitability and lowest anthropogenic pressure, measured as distance from urban areas and highways (>5 km). Protecting the areas identified in this study from anthropogenic threats such as hunting and selective logging will help to preserve not only the cock-of-the-rock, but also the biodiversity of the whole mosaic of habitats in the region. Our results were incorporated in a regional management plan developed by state agencies and non-governmental organizations. Geographic Information Systems and ecological niche modeling techniques combined with on the ground, local surveys can be useful in species conservation efforts, for planning new inventories, prioritizing areas to be protected, and for creating ecological corridors.

Emergent aquatic insects can provide inputs to terrestrial ecosystems near lentic and lotic waterbodies, producing ecosystem linkages at the aquatic–terrestrial interface. Although aquatic insect emergence has been examined for individual sites, the magnitude and spatial distribution of this phenomenon has not been examined at regional spatial scales. Here, we characterize this cross-habitat linkage for the state of Wisconsin, USA (169,639 km2). We combined GIS hydrological data with empirical data and predictive models of aquatic insect production to estimate annual aquatic emergence for the state of Wisconsin. Total emergence (lentic + lotic) was estimated to be about 6,800 metric tons of C y−1. Lentic systems comprised 79% of total estimated insect emergence, primarily due to the large amount of lake surface area relative to streams. This is due to both basic ecosystem geometry and the overall abundance of lakes in Wisconsin. Spatial variation was high: insect emergence in southwestern Wisconsin was dominated by streams, whereas for most of the rest of the state insect emergence was dominated by lakes. Lentic inputs to land were highly concentrated (relative to lotic inputs) because lakes have a high ratio of surface area to buffer area. Although less concentrated, the spatial extent of lotic influence was greater: statewide, four times more land area fell within the 100 m buffer zones of streams compared to lakes. Large waterbodies (almost all of which were lakes) were hotspots of insect emergence and input to land. Aquatic insect inputs exceed estimated terrestrial secondary production in 13% of buffer area, and by a factor of 100 or more adjacent to large lakes (>50,000 ha). The model sensitivity analysis showed that the simplifying assumptions and sources of potential error in the input variables had a minor impact on the overall results.

Recent technological and methodological advances in the field of imaging spectroscopy (or hyperspectral imaging) make possible new approaches to studying regional ecosystem processes and structure. We use Earth Observing-1 Hyperion satellite hyperspectral imagery to test our ability to identify tree species in a lowland Peruvian Amazon forest, and to investigate seasonal variation in species detections related to phenology. We obtained four images from 2006-2008, and used them to spectrally differentiate crowns of 42 individual trees of 5 taxa using linear discriminant analysis. Temporal variation of tree spectra was assessed using three methods, based on 1) position of spectra in a two-dimensional canonical variable space, 2) a broadband, multispectral dataset derived from sets of narrow bands identified as informative to spectrally separate taxa, and 3) narrow band vegetation indices (photochemical reflectance index and anthocyanin reflectance index) sensitive to leaf pigments. We obtained high classification success with a reduced set of trees (28 individuals) whose crowns were well represented on Hyperion 30 m resolution pixels. Temporal variability of spectra was confirmed by each of the three methods employed. Understanding seasonality of spectral characteristics of tropical tree crowns has implications in spectral based multi-seasonal species mapping and studying ecosystem processes.

Survival and reproduction are the two primary life-history traits essential for species' persistence; however, the environmental conditions that support each of these traits may not be the same. Despite this, reproductive requirements are seldom considered when estimating species' potential distributions. We sought to examine potentially limiting environmental factors influencing the distribution of an oviparous reptile of conservation concern with respect to the species' survival and reproduction and to assess the implications of the species' predicted climatic constraints on current conservation practices. We used ecological niche modeling to predict the probability of environmental suitability for the alligator snapping turtle (Macrochelys temminckii). We built an annual climate model to examine survival and a nesting climate model to examine reproduction. We combined incubation temperature requirements, products of modeled soil temperature data, and our estimated distributions to determine whether embryonic development constrained the northern distribution of the species. Low annual precipitation constrained the western distribution of alligator snapping turtles, whereas the northern distribution was constrained by thermal requirements during embryonic development. Only a portion of the geographic range predicted to have a high probability of suitability for alligator snapping turtle survival was estimated to be capable of supporting successful embryonic development. Historic occurrence records suggest adult alligator snapping turtles can survive in regions with colder climes than those associated with consistent and successful production of offspring. Estimated egg-incubation requirements indicated that current reintroductions at the northern edge of the species' range are within reproductively viable environmental conditions. Our results highlight the importance of considering survival and reproduction when estimating species' ecological niches, implicating conservation plans, and benefits of incorporating physiological data when evaluating species' distributions.

Aim Regional movements of tropical birds are among the least understood patterns of migration, generally assumed to be related to seasonality of vegetation and food resources. We used readily available remotely sensed data to analyse this relationship in the three-wattled bellbird (Procnias tricarunculatus), an IUCN Vulnerable canopy frugivorous bird that undergoes localized altitudinal and latitudinal movements between several non-breeding and breeding ranges. Location Central America. Methods We generated ecological niche models (GARP and Maxent) based on remotely sensed vegetation indices (enhanced vegetation index, EVI; red index, RI; and normalized difference water index, NDWI) that were used as proxies for canopy characteristics and phenological changes between seasons. The variation in EVI was also analysed in relation to known bellbird seasonal migration patterns. Results Remotely sensed summaries of intra-annual vegetation variation could not explain known movement patterns of bellbirds breeding in Monteverde Cloud Forest Reserve, Costa Rica. The ecological niche modelling (ENM) framework used for exploring potential movement patterns of another population of bellbirds, observed in March 2004 in Corcovado National Park, Costa Rica, showed that the Atlantic and Pacific lowlands are suitable for the bellbirds year-round, while middle elevations, where breeding may occur, have limited suitability. Main conclusions Our findings suggest that: (1) the Corcovado population tracks similar environmental conditions during the non-breeding season; (2) migration to middle elevation breeding sites might be related to factors other than vegetation seasonality or breeding might not be restricted to these elevation ranges; and (3) the lowlands comprising most of the suitable areas for bellbirds are where anthropogenic pressure is highest, so conservation status should consider this threat, and conservation planning should emphasize these areas.

As zebra mussels (Dreissena polymorpha) continue to spread among inland lakes of the United States and Canada, there is growing interest from professionals, citizens, and other stakeholders to know which lakes are likely to be colonized by zebra mussels. Thus, we developed a classification of lake suitability for zebra mussels on the basis of measured or estimated concentrations of dissolved calcium in lake water and applied the classification to >11,500 lakes in Wisconsin and the Upper Peninsula of Michigan. The majority of lakes (58%) were classified as unsuitable (

Aim Geographic distributions of species are constrained by several factors acting at different scales, with climate assumed to be a major determinant at broad extents. Recent studies, however, have challenged this statement and indicated that climate may not dominate among the factors governing geographic distributions of species. Here, we argue that these results are misleading due to the lack of consideration of the geographic area that has been accessible to the species. Location North America. Methods We generated null distributions for 75 North American endemic and 19 non-endemic bird species. For each species, climatic envelopes of observed and null distributions were modelled using neural networks and generalized linear models, and seven climatic predictors. Values of the area under the receiver–operating characteristic curve (AUC) based on models of observed distributions were compared with corresponding AUC values for the null distributions. Results More than 82% of the endemic species showed AUC higher for the observed than for the null distributions, while 63% of the non-endemic species showed such a pattern. Main conclusions We demonstrate a dominant climatic signal in shaping North American bird distributions. Our results attest to the importance of climate in determining species distributions and support the use of climate-envelope models for estimating potential distributional areas at the appropriate spatial scales.

Human-lion conflict is one of the leading threats to lion populations and while livestock loss is a source of conflict, the degree to which livestock depredation is tolerated by people varies between regions and across cultures. Knowledge of local attitudes towards lions and identification of drivers of human-lion conflict can help formulate mitigation measures aimed at promoting coexistence of humans with lions. We assessed locals’ attitudes towards lions in and around Gambella National Park and compared the findings with published data from Kafa Biosphere Reserve, both in western Ethiopia. We used household interviews to quantify livestock loss. We found that depredation was relatively low and that disease and theft were the top factors of livestock loss. Remarkably, however, tolerance of lions was lower around Gambella National Park than in Kafa Biosphere Reserve. Multivariate analysis revealed that education level, number of livestock per household, livestock loss due to depredation, and livestock loss due to theft were strong predictors of locals’ attitude towards lion population growth and conservation. We show that the amount of livestock depredation alone is not sufficient to understand human-lion conflicts and we highlight the importance of accounting for cultural differences in lion conservation. The low cultural value of lions in the Gambella region corroborate the findings of our study. In combination with growing human population and land-use change pressures, low cultural value poses serious challenges to long-term lion conservation in the Gambella region. We recommend using Arnstein’s ladder of participation in conservation education programs to move towards proactive involvement of locals in conservation.

Questions: Understanding distributions of tree species at landscape scales in tropical forests is a difficult task that could benefit from the recent development of satellite imaging spectroscopy. We tested an application of the EO-1 Hyperion satellite sensor to spectrally detect the location of five important tree taxa in the lowland humid tropical forests of southeastern Peru. Location: Peru, Departamento de Madre de Dios. Methods: We used linear discriminant analysis with a stepwise selection procedure to analyze two Hyperion datasets (July and December 2006) to choose the most informative narrow bands for classifying trees. Results: Optimal channels selected were different between the two seasons. Classification was 100% successful for the five taxa when using 25 narrow bands and pixels that represented >40% of tree crowns. We applied the discriminant functions developed separately for the two seasons to the entire study area, and found significantly nonrandom overlap in the anticipated distributions of the five taxa between seasons. Conclusions: Despite known issues, such as signal-to-noise ratio and spatial resolution, Hyperion imaging spectroscopy has potential for developing regional mapping of large-crowned tropical trees.

Birds concentrated in riparian habitats are poorly sampled by traditional survey methods because of the difficulties associated with accessing these habitats. Our objectives were to test the effectiveness of river-based surveys to determine the status, distribution, and relative abundance for riparian bird species in Missouri and northern Arkansas, with special emphasis on Dendroica cerulea (Cerulean Warbler). Our canoe-based surveys revealed an average of 2.3 and 0.8 singing male Cerulean Warblers/river km along the Current River (128 river km surveyed), MO, and the Buffalo National River (96 river km), AR. Nonparametric estimates for repeated surveys of the same river stretches indicate that 69–79% of singing male Cerulean Warblers were detected. However, the bias associated with the estimate methodology and independent song rate data suggest those are conservative estimates. In comparison with land-based point-counts, this river-based protocol offers a quick and efficient assessment of Cerulea...

We assessed song rates among male Cerulean Warblers (Dendroica cerulea) in Ozark riparian forest in southeastern Missouri to characterize song rate variation and estimate how many males may be missed during censuses. Average (± SD) songs per 5-min intervals for continuous 4-hr observation periods varied from 3.1 ± 4.8 (mated males) to 36.0 ± 18.7 (unmated males; n = 24 males). Unmated males averaged twice the number of songs per 5-min periods than mated males. Considerable song rate variation existed even among mated males. Song rates slightly declined over the 4-hr observation period. Song rate differences between Cerulean Warblers in Ontario and southeastern Missouri suggest caution when making assumptions about breeding status based on auditory surveys. Average male Cerulean Warbler territory size (n = 20) was 0.9 ± 0.1 ha with 27 of 31 males having at least one abutting conspecific territory. All males (n = 24) were silent for 32.7 ± 21.5 and 21.8 ± 17.4% of the 5-min and 10-min periods, resp...

The area under the curve (AUC) of the receiver operating characteristic (ROC) has become a dominant tool in evaluating the accuracy of models predicting distributions of species. ROC has the advantage of being threshold-independent, and as such does not require decisions regarding thresholds of what constitutes a prediction of presence versus a prediction of absence. However, we show that, comparing two ROCs, using the AUC systematically undervalues models that do not provide predictions across the entire spectrum of proportional areas in the study area. Current ROC approaches in ecological niche modeling applications are also inappropriate because the two error components are weighted equally. We recommend a modification of ROC that remedies these problems, using partial-area ROC approaches to provide a firmer foundation for evaluation of predictions from ecological niche models. A worked example demonstrates that models that are evaluated favorably by traditional ROC AUCs are not necessarily the best when niche modeling considerations are incorporated into the design of the test.

The virus family Filoviridae includes 2 genera, the Marburg viruses and the Ebola viruses. The ecology of the filoviruses is poorly known, and indeed their host relationships remain completely unknown. An earlier effort prioritized mammalian taxa as to their possible status as the long-term coevolved reservoir of the filoviruses based on a coarse, regional classification of occurrences; here, we greatly refine the geographic data set for the mammalian taxa based on rich occurrence data sets and range interpolations from ecological niche models for each species involved. This improved detail permits a much more detailed inspection of distributional overlap patterns, and consequently a shorter list of candidate taxa-geographic analysis of 124 mammalian clades led to identification of 55 groups of interest that coincide spatially with known filovirus outbreaks, and fulfill the requirements of several additional assumptions. We discuss implications of our results for the search for the filovirus reservoir, and for research in African mammalogy.

We compared predictive success in two common algorithms for modeling species' ecological niches, GARP and Maxent, in a situation that challenged the algorithms to be generalthat is, to be able to predict the species' distributions in broad unsampled regions, here termed transferability. The results were strikingly different between the two algorithmsMaxent models reconstructed the overall distributions of the species at low thresholds, but higher predictive levels of Maxent predictions reflected overfitting to the input data; GARP models, on the other hand, succeeded in anticipating most of the species' distributional potential, at the cost of increased (apparent, at least) commission error. Receiver operating characteristic (ROC) tests were weak in discerning models able to predict into broad unsampled areas from those that were not. Such transferability is clearly a novel challenge for modeling algorithms, and requires different qualities than does predicting within densely sampled landscapesin this case, Maxent was transferable only at very low thresholds, and biases and gaps in input data may frequently affect results based on higher Maxent thresholds, requiring careful interpretation of model results.

The conservation of poorly known species is difficult because of incomplete knowledge on their biology and distribution. We studied the contribution of two ecological niche modelling tools, the Genetic Algorithm for Rule-set Prediction (GARP) and maximum entropy (Maxent), in assessing potential ranges and distributional connectivity among 12 of the least known African and Asian viverrids. The level of agreement between GARP and Maxent predictions was low when < 15 occurrences were available, probably indicating a minimum number below that necessary to obtain models with good predictive power. Unexpectedly, our results suggested that Maxent extrapolated more than GARP in the context of small sample sizes. Predictions were overlapped with current land use and location of protected areas to estimate the conservation status of each species. Our analyses yielded range predictions generally contradicting with extents of occurrence established by the IUCN. We evidenced a high level of disturbance within predicted distributions in West and East Africa, Sumatra, and South-East Asia, and identified within West African degraded lowlands four relatively preserved areas that might be of prime importance for the conservation of rainforest taxa. Knowing whether these species of viverrids may survive in degraded or alternative habitats is of crucial importance for further conservation planning. The level of coverage of species suitable ranges by existing and proposed IUCN reserves was low, and we recommend that the total surface of protected areas be substantially increased on both continents.

Comprehensive biodiversity surveys are unavailable for most Central and Eastern European countries. Although birds in general are well-studied, distributional information in the region is sparse and largely out-of of-date; I used museum specimen locality records and raster GIS data layers summarizing environmental dimensions to produce distributional hypotheses for the 36 threatened and endangered bird species in the region using ecological niche modeling. These ecological niche models were also used to predict likely future (2055) distributional shifts owing to global climate change. The entire suite of distributional information that resulted was used to evaluate strategies for conservation via simple heuristic place-prioritization algorithms based on complementarity and rarity considerations. These analyses identified priority areas in southern and eastern Romania, as well as other areas across the region, as priority targets for conservation action in the region.

The demands of a growing human population dictates that expansion of energy infrastructure, roads, and other development frequently takes place in native rangelands. Particularly, transmission lines and roads commonly divide rural landscapes and increase fragmentation. This has direct and indirect consequences on native wildlife that can be mitigated through thoughtful planning and proactive approaches to identifying areas of high conservation priority. We used nine years (2003–2011) of Greater Prairie-Chicken (Tympanuchus cupido) lek locations totaling 870 unique leks sites in Kansas and seven geographic information system (GIS) layers describing land cover, topography, and anthropogenic structures to model habitat suitability across the state. The models obtained had low omission rates (0.81), indicating high model performance and reliability of predicted habitat suitability for Greater Prairie-Chickens. We found that elevation was the most influential in predicting lek locations, contributing three times more predictive power than any other variable. However, models were improved by the addition of land cover and anthropogenic features (transmission lines, roads, and oil and gas structures). Overall, our analysis provides a hierarchal understanding of Greater Prairie-Chicken habitat suitability that is broadly based on geomorphological features followed by land cover suitability. We found that when land features and vegetation cover are suitable for Greater Prairie-Chickens, fragmentation by anthropogenic sources such as roadways and transmission lines are a concern. Therefore, it is our recommendation that future human development in Kansas avoid areas that our models identified as highly suitable for Greater Prairie-Chickens and focus development on land cover types that are of lower conservation concern.

Natural history collections are crucial resources for conservation biology, particularly given the development of the ecological niche modeling (ENM) approach. We combined ENM with taxonomic investigations to address ecological, geographic, and phenotypic variation in the poorly known central African rainforest genets (Genetta cristata, Genetta servalina, Genetta victoriae) to provide new insights into their conservation status. Taxonomic identification was based on four discrete morphological characters. ENMs were developed using the Genetic Algorithm for Rule-Set Prediction (GARP), 10 environmental data layers and 310 georeferenced localities extracted from 667 museum specimens and 22 literature sources. Re-assessed taxonomic identifications allowed us to expand significantly the known range and ecological limits of the three genets. We suggested limited hybridization between G. cristata and G. servalina, in a zone of sympatry likely to cover central Cameroon, northwestern Gabon and Congo. ENM showed that almost all known occurrences were connected geographically by suitable ecological conditions, suggesting continuous potential distributions between supposedly isolated populations of the three genets. Our investigations indicated that G. cristata is distinct from G. servalina in morphology, geographic ranges and ecological niches, indicating species status for G. cristata, which, as such, should be the subject of appropriate conservation attention. Areas of predicted connectivity and actual zones of occurrence falling outside current forest cover should be surveyed to re-assess the status of the rainforest genets. Our study shows that combining ENM and taxonomic investigations can substantially improve data utilization from natural history collections, especially in the case of poorly known species.

African giant pouched rats (Cricetomys) are native to tropical Africa, where they range from Senegal and Gambia east across West Africa and the Congo Basin to the Indian Ocean coast of East Africa. Ecological niche models show that Cricetomys species differ in their invasive potential. Although neither of the presently recognized Cricetomys species appears to have genuinely broad distributional potential in North America, models predict that C. emini would have extremely restricted distributional potential, whereas C. gambianus would have a broader potential across the southeastern United States.

Ecological niche models (ENMs) have increasingly been used to estimate the potential effects of climate change on species’ distributions worldwide. Recently, predictions of species abundance have also been obtained with such models, though knowledge about the climatic variables affecting species abundance is often lacking. To address this, we used a well-studied guild (temperate North American quail) and the Maxent modeling algorithm to compare model performance of three variable selection approaches: correlation/variable contribution (CVC), biological (i.e., variables known to affect species abundance), and random. We then applied the best approach to forecast potential distributions, under future climatic conditions, and analyze future potential distributions in light of available abundance data and presence-only occurrence data. To estimate species’ distributional shifts we generated ensemble forecasts using four global circulation models, four representative concentration pathways, and two time periods (2050 and 2070). Furthermore, we present distributional shifts where 75%, 90%, and 100% of our ensemble models agreed. The CVC variable selection approach outperformed our biological approach for four of the six species. Model projections indicated species-specific effects of climate change on future distributions of temperate North American quail. The Gambel’s quail (Callipepla gambelii) was the only species predicted to gain area in climatic suitability across all three scenarios of ensemble model agreement. Conversely, the scaled quail (Callipepla squamata) was the only species predicted to lose area in climatic suitability across all three scenarios of ensemble model agreement. Our models projected future loss of areas for the northern bobwhite (Colinus virginianus) and scaled quail in portions of their distributions which are currently areas of high abundance. Climatic variables that influence local abundance may not always scale up to influence species’ distributions. Special attention should be given to selecting variables for ENMs, and tests of model performance should be used to validate the choice of variables.

Ecological niche modeling (ENM) uses species’ known occurrences and environmental variables to estimate potential geographic distributions. The potential distribution of a species can be updated and refined after new occurrences are collected; therefore, we developed an online application (Armadillo Mapper [AM]) that automatically updates the ecological niche model for the hairy long-nosed armadillo (Dasypus pilosus) with new observations and provides a revised potential distribution map. AM can be used by researchers and conservation practitioners without a deep knowledge of geographic information system (GIS) techniques and ENM. Here, we introduce this online application and demonstrate the use of our application with a new observation of D. pilosus. AM has the potential to be extended to other species and to bridge the gap between distributional knowledge synthesized in a computer lab and conservation efforts carried out in the field.

The hairy long-nosed armadillo (Dasypus pilosus) is endemic to the Andes in Peru and rarely studied, thus more investigations are needed. To gain a better understanding of this species’ distributio...

Invasive species are leading drivers of environmental change. Their impacts are often linked to their population size, but surprisingly little is known about how frequently they achieve high abundances. A nearly universal pattern in ecology is that species are rare in most locations and abundant in a few, generating right-skewed abundance distributions. Here, we use abundance data from over 24,000 populations of 17 invasive and 104 native aquatic species to test whether invasive species differ from native counterparts in statistical patterns of abundance across multiple sites. Invasive species on average reached significantly higher densities than native species and exhibited significantly higher variance. However, invasive and native species did not differ in terms of coefficient of variation, skewness, or kurtosis. Abundance distributions of all species were highly right skewed (skewness>0), meaning both invasive and native species occurred at low densities in most locations where they were present. The average abundance of invasive and native species was 6% and 2%, respectively, of the maximum abundance observed within a taxonomic group. The biological significance of the differences between invasive and native species depends on species-specific relationships between abundance and impact. Recognition of cross-site heterogeneity in population densities brings a new dimension to invasive species management, and may help to refine optimal prevention, containment, control, and eradication strategies.

In this study, we sampled aquatic snails for the presence of hairworm cysts from 46 streams in Payne County, Oklahoma. Gordiid cysts were found at 70 % (32/46) of sites examined. Based on cyst morphology, we were able to identify three morphological types of gordiid cysts, including Paragordius, Gordius, and Chordodes/Neochordodes. Using our gordiid cyst presence data in conjunction with environmental variables, we developed an ecological niche model using Maxent to identify areas suitable for snail infections with gordiids. The model successfully predicted all presence localities of gordiid cysts in snails over a geographic area of 1,810 km2. We used this information, along with arthropod host infections and crowdsourcing, citizen scientists sampling for adult free-living worms during peak emergent times in areas predicted suitable by the model, to document Paragordius varius, Chordodes morgani, and a new species of gordiid (Gordius n. sp.). To our knowledge, this is the first ecological niche model attempted on such a narrow geographic scale (county level) that recovered known locations successfully. We provide new scanning electron micrographs and molecular data for these species. Our field data and ecological niche model clearly indicate that gordiid cysts are easy to detect in the environment and together these sampling techniques can be useful in discovering new species of gordiids, even in relatively well sampled areas for these cryptic parasites.

The ecological distribution of Cytauxzoon felis, an often-fatal tick-borne apicomplexan that infects domestic cats, has not been evaluated or identified despite its continued emergence. Infection of C. felis is characterized by lethargy, icterus, fever, anorexia, anemia, and death. The natural vertebrate reservoir of C. felis is the bobcat (Lynx rufus). To determine the possible distribution of C. felis in three states where infection is common (Oklahoma, Missouri, and Arkansas), two separate approaches to ecological niche modeling were implemented. First, a model relating several different climatic layers to geographic locations where cases of C. felis infection were confirmed in domestic cats was developed to predict the possible distribution of the parasite. The second model incorporated occurrences of bobcats with environmental layers and land cover suitable for tick vectors to identify areas of overlap where C. felis transmission was likely. Results of both models indicated a high probability of C. felis from central Oklahoma to south-central Missouri. However, other predicted areas of C. felis occurrence varied between the two modeling approaches. Modeling the vertebrate reservoir and the tick vector predicted a broader possible distribution compared to modeling cases of C. felis infection in domestic cats. Our results suggest that C. felis is likely to extend beyond areas predicted by case modeling due to the presence of both the vector and reservoir.

Success of the cattle industry in Latin America is impeded by the common vampire bat, Desmodus rotundus, through decreases in milk production and mass gain and increased risk of secondary infection and rabies. We used ecological niche modeling to predict the current potential distribution of D. rotundus and the future distribution of the species for the years 2030, 2050, and 2080 based on the A2, A1B, and B1 climate scenarios from the Intergovernmental Panel on Climate Change. We then combined the present day potential distribution with cattle density estimates to identify areas where cattle are at higher risk for the negative impacts due to D. rotundus. We evaluated our risk prediction by plotting 17 documented outbreaks of cattle rabies. Our results indicated highly suitable habitat for D. rotundus occurs throughout most of Mexico and Central America as well as portions of Venezuela, Guyana, the Brazilian highlands, western Ecuador, northern Argentina, and east of the Andes in Peru, Bolivia, and Paraguay. With future climate projections suitable habitat for D. rotundus is predicted in these same areas and additional areas in French Guyana, Suriname, Venezuela and Columbia; however D. rotundus are not likely to expand into the U.S. because of inadequate 'temperature seasonality.' Areas with large portions of cattle at risk include Mexico, Central America, Paraguay, and Brazil. Twelve of 17 documented cattle rabies outbreaks were represented in regions predicted at risk. Our present day and future predictions can help authorities focus rabies prevention efforts and inform cattle ranchers which areas are at an increased risk of cattle rabies because it has suitable habitat for D. rotundus.

Most spiders use venom to paralyze their prey and are commonly feared for their potential to cause injury to humans. In North America, one species in particular, Loxosceles reclusa (brown recluse spider, Sicariidae), causes the majority of necrotic wounds induced by the Araneae. However, its distributional limitations are poorly understood and, as a result, medical professionals routinely misdiagnose brown recluse bites outside endemic areas, confusing putative spider bites for other serious conditions. To address the issue of brown recluse distribution, we employ ecological niche modeling to investigate the present and future distributional potential of this species. We delineate range boundaries and demonstrate that under future climate change scenarios, the spider's distribution may expand northward, invading previously unaffected regions of the USA. At present, the spider's range is centered in the USA, from Kansas east to Kentucky and from southern Iowa south to Louisiana. Newly influenced areas may include parts of Nebraska, Minnesota, Wisconsin, Michigan, South Dakota, Ohio, and Pennsylvania. These results illustrate a potential negative consequence of climate change on humans and will aid medical professionals in proper bite identification/treatment, potentially reducing bite misdiagnoses.

The past two decades have seen major outbreaks of influenza viruses and flaviviruses that are spread at least in part by migratory birds. Although much new information has accumulated on the natural history of the viruses, and on the geography of migration by individual bird species, no synthesis has been achieved regarding likely patterns of spread of such pathogens by migratory birds, which constitutes a large-scale challenge in understanding the geography of bird migration. We here present a first step in this direction: a summary of seasonal (breeding, wintering) distributions of all 392 North American bird species that show marked seasonal migratory movements and that meet a series of conditions for inclusion in our analyses. We use species-level interseasonal connectivity among distributional areas to make initial forecasts of patterns of spread of bird-borne diseases via bird migration. We identify key next steps towards improved forecasting of spread patterns of bird-borne pathogens in North America, which will require substantial improvements in knowledge of the geography of bird migration.

The plant family Orobanchaceae includes many parasitic weeds that are also impressive invaders and aggressive crop pests with several specialized features (e.g. microscopic seeds, parasitic habits). Although they have provoked several large-scale eradication and control efforts, no global evaluation of their invasive potential is as yet available. We use tools from ecological niche modeling in combination with occurrence records from herbarium specimens to evaluate the global invasive potential of each of 10 species in this assemblage, representing several of the worst global invaders. The invasive potential of these species is considerable, with all tropical and subtropical countries, and most temperate countries, vulnerable to invasions by one or more of them.

Given the possibility of highly pathogenic H5N1 avian influenza arriving in North America and monitoring programs that have been established to detect and track it, we review intercontinental movements of birds. We divided 157 bird species showing regular intercontinental movements into four groups based on patterns of movement-one of these groups (breed Holarctic, winter Eurasia) fits well with the design of the monitoring programs (i.e., western Alaska), but the other groups have quite different movement patterns, which would suggest the importance of H5N1 monitoring along the Pacific, Atlantic, and Gulf coasts of North America.

Climate warming is one of the most important threats to biodiversity. Ectothermic organisms such as amphibians and reptiles are especially vulnerable as climatic conditions affect them directly. Ecological niche models (ENMs) are increasingly popular in ecological studies, but several drawbacks exist, including the limited ability to account for the dispersal potential of the species. In this study, we use ENMs to explore the impact of global climate change on the Caspian whip snake (Dolichophis caspius) as model for organisms with low dispersal abilities and to quantify dispersal to novel areas using GIS techniques. Models generated using Maxent 3.3.3 k and GARP for current distribution were projected on future climatic scenarios. A cost-distance analysis was run in ArcGIS 10 using geomorphological features, ecological conditions, and human footprint as “costs” to dispersal of the species to obtain a Maximum Dispersal Range (MDR) estimate. All models developed were statistically significant (P

Rabies remains a disease of significant public health concern. In the Americas, bats are an important source of rabies for pets, livestock, and humans. For effective rabies control and prevention, identifying potential areas for disease occurrence is critical to guide future research, inform public health policies, and design interventions. To anticipate zoonotic infectious diseases distribution at coarse scale, veterinary epidemiology needs to advance via exploring current geographic ecology tools and data using a biological approach. We analyzed bat-borne rabies reports in Chile from 2002 to 2012 to establish associations between rabies occurrence and environmental factors to generate an ecological niche model (ENM). The main rabies reservoir in Chile is the bat species Tadarida brasiliensis; we mapped 726 occurrences of rabies virus variant AgV4 in this bat species and integrated them with contemporary Normalized Difference Vegetation Index (NDVI) data from the Moderate Resolution Imaging Spectroradiometer (MODIS). The correct prediction of areas with rabies in bats and the reliable anticipation of human rabies in our study illustrate the usefulness of ENM for mapping rabies and other zoonotic pathogens. Additionally, we highlight critical issues with selection of environmental variables, methods for model validation, and consideration of sampling bias. Indeed, models with weak or incorrect validation approaches should be interpreted with caution. In conclusion, ecological niche modeling applications for mapping disease risk at coarse geographic scales have a promising future, especially with refinement and enrichment of models with additional information, such as night-time light data, which increased substantially the model’s ability to anticipate human rabies. Electronic supplementary material The online version of this article (doi:10.1186/s13567-015-0235-7) contains supplementary material, which is available to authorized users.