Niche Distribution Research Articles

Biocrust ecology: unifying micro- and macro-scales to confront global change.

Biocrust ecology: unifying micro- and macro-scales to confront global change.

Assessing the potential of translocating vulnerable forest birds by searching for novel and enduring climatic ranges.

Hawaiian forest birds are imperiled, with fewer than half the original >40 species remaining extant. Recent studies document ongoing rapid population decline and project complete climate‐based range losses for the critically endangered Kaua'i endemics ‘akeke’e (Loxops caeruleirostris) and ‘akikiki (Oreomystis bairdi) by end‐of‐century due to projected warming. Climate change facilitates the upward expansion of avian malaria into native high elevation forests where disease was historically absent. While intensified conservation efforts attempt to safeguard these species and their habitats, the magnitude of potential loss and the urgency of this situation require all conservation options to be seriously considered. One option for Kaua’i endemics is translocation to islands with higher elevation habitats. We explored the feasibility of interisland translocation by projecting baseline and future climate‐based ranges of ‘akeke’e and ‘akikiki across the Hawaiian archipelago. For islands where compatible climates for these species were projected to endure through end‐of‐century, an additional climatic niche overlap analysis compares the spatial overlap between Kaua’i endemics and current native species on prospective destination islands. Suitable climate‐based ranges exist on Maui and Hawai'i for these Kaua'i endemics that offer climatically distinct areas compared to niche distributions of destination island endemics. While we recognize that any decision to translocate birds will include assessing numerous additional social, political, and biological factors, our focus on locations of enduring and ecologically compatible climate‐based ranges represents the first step to evaluate this potential conservation option. Our approach considering baseline and future distributions of species with climatic niche overlap metrics to identify undesirable range overlap provides a method that can be utilized for other climate‐vulnerable species with disjointed compatible environments beyond their native range.

Light Absorption in Coralline Algae (Rhodophyta): A Morphological and Functional Approach to Understanding Species Distribution in a Coral Reef Lagoon

Red coralline algae are a cosmopolitan group with the ability to precipitate CaCO3 within the walls of their vegetative cells. The resultant carbonate structure is key for explaining their ecological success, as it provides protection against herbivores and resistance to water motion. However, its potential contribution to enhance thallus light absorption efficiency through multiple light scattering on algal skeleton, similar to the effect documented for scleractinian corals, has not been yet investigated. Here, we initiate this analysis, characterizing thallus optical properties of three coralline species, which differed in pigment content and thallus mass area (TMA, gDW m-2). The three species, the rhodolith Neogoniolithon sp., the crustose coralline alga (CCA), Lithothamnion sp., and the articulated alga Amphiroa tribulus, represent the more distinctive coralline growth-forms and were able to colonize contrasting light environments in Caribbean coral reefs. The thicker thalli of the rhodoliths were the most efficient light collectors, as evidenced by their higher pigment absorption efficiency (a*Chla; m2 mgChla-1) and photosynthetic rates per unit area. This could explain rhodolith success in oligotrophic, highly illuminated reef environments. In contrast, the thinner thalli of the CCA, a low-light specialist, showed the highest metabolic rates normalized to mass and the highest light absorption efficiencies per unit mass (a*M; m2 gdw-1). Therefore, the ecological success of the CCA in cryptic habitats within the reef cannot be explained only by its low-light physiology, but also by its capacity to reduce the structural costs of their thalli, and thus of its new growth. Lastly, the ecological success of Amphiroa tribulus, which displayed intermediate values for the efficiency of light absorption, metabolic rates and TMA, was explained by its ability to construct the largest light collectors (algal canopies) thanks to the presence of flexible, non-calcified segments (genicula). This ability enables enhanced photosynthetic and carbonate production at the organism/canopy level. The resulting fragile canopy survives best within the protection provided by colonies of the lettuce coral Agaricia agaricites. In conclusion, our study demonstrates the utility of optical traits as powerful tools to investigate differences in the competitive abilities, abundances and niche distribution among algal species and/or growth-forms.

Range expansion potential of two co-occurring invasive vines to marginal habitats in Turkey

Niche distribution models accurately predict the potential distribution range of invasive plants into new habitats based on their climatic requirements in the native regions. However, these models usually ignore the marginal habitats which can limit the distribution of exotic plants. We therefore tested the seedling survival, growth and nutrient acquisition capabilities of two co-occurring invasive vines [Persicaria perfoliata (L.) H. Gross and Sicyos angulatus L.] in three different manipulative greenhouse experiments to infer their range expansion potential to marginal habitats in Turkey. First experiment included five different moisture availability regimes (100, 75, 50, 25 and 12.5% available water), second experiment consisted of four different salinity levels (0, 3, 6 and 12 dSm−1 soil salinity) and third experiment had four different soil textures (clay-1, clay-2, sandy loam and silt-clay-loam). Seedling mortality was only observed under extreme moisture deficiency in both plant species, while most of the transplanted seedlings of both species did not survive under 6 and 12 dSm−1 salinity levels. Soil textures had no effect on seedling survival. POLPE better tolerated low moisture availability and high salinity compared to SIYAN. Biomass production in both plant species was linearly reduced with increasing salinity and moisture deficiency. SIYAN invested more resources towards shoot, accumulated higher K and P, whereas POLPE maintained higher root-to-shoot ratio under all experimental conditions. Both plant species employed different strategies to cope with adverse environmental conditions, but failed to persist under high soil salinity and moisture deficiency. Our study suggest that both plant species have limited potential of range expansion to marginal habitats and will be limited to moist and humid areas only. Therefore, further research activities should be concentrated in these regions to develop effective management strategies against both species.

The pathological structure of the perivascular niche in different microvascular patterns of glioblastoma.

The perivascular niche is critical for intercellular communication between resident cell types in glioblastoma (GBM), and it plays a vital role in maintaining the glioma stem cell (GSC) microenvironment. It is shown in abundant research that different microvascular patterns exist in GBM; and it can be implied that different microvascular patterns are associated with different pathological structures in the perivascular niche. However, the pathological structure of the perivascular niche is still not clear. Here, we investigated the distribution and biological characteristics of different microvascular pattern niches (MVPNs) in GBM by detecting the expression of CD34, CD133, Nestin, α-SMA, GFAP and CD14 in the perivascular niche using multiple -fluorescence. The four basic microvascular patterns are microvascular sprouting (MS), vascular cluster (VC), vascular garland (VG), and glomeruloid vascular proliferation (GVP). By analyzing the proportion of the area of each marker in four types of formations, the results indicated that the expression of CD34, CD133 and Nestin in MS and VC was significantly lower than that in VG and GVP (P<0.05). Furthermore, the results showed that α-SMA expression different in the MS, VC, VG and GVP (P<0.05). However, the expression of GFAP and CD14 in each type of formation exhibited no significant difference (P>0.05). According to the area distributions of different markers, we mapped four precise simulation diagrams to provide an effective foundation for the accurate simulation of glioblastoma in vitro.

A comprehensive framework for the study of species co‐occurrences, nestedness and turnover

Binary presence–absence matrices (rows = species, columns = sites) are often used to quantify patterns of species co‐occurrence, and to infer possible biotic interactions from these patterns. Previous classifications of co‐occurrence patterns as nested, segregated, or modular have led to contradictory results and conclusions. These analyses usually do not incorporate the functional traits of the species or the environmental characteristics of the sites, even though the outcomes of species interactions often depend on trait expression and site quality. Here we address this shortcoming by developing a method that incorporates realized functional and environmental niches, and relates them to species co‐occurrence patterns. These niches are defined from n‐dimensional ellipsoids, and calculated from the n eigenvectors and eigenvalues of the variance–covariance matrix of measured environmental or trait variables. Average niche overlap among species and the spatial distribution of niches define a triangle plot with vertices of species segregation (low niche overlap), nestedness (high niche overlap), and modular co‐occurrence (clusters of overlapping niches). Applying this framework to temperate understorey plant communities in southwest Poland, we found a consistent modular structure of species occurrences, a pattern not detected by conventional presence–absence analysis. These results suggest that, in our case study, habitat filtering is the most important process structuring understorey plant communities. Furthermore, they demonstrate how incorporating trait and environmental data into co‐occurrence analysis improves pattern detection and provides a stronger theoretical framework for understanding community structure.

Potential distribution of mosquito vector species in a primary malaria endemic region of Colombia.

Rapid transformation of natural ecosystems changes ecological conditions for important human disease vector species; therefore, an essential task is to identify and understand the variables that shape distributions of these species to optimize efforts toward control and mitigation. Ecological niche modeling was used to estimate the potential distribution and to assess hypotheses of niche similarity among the three main malaria vector species in northern Colombia: Anopheles nuneztovari, An. albimanus, and An. darlingi. Georeferenced point collection data and remotely sensed, fine-resolution satellite imagery were integrated across the Urabá –Bajo Cauca–Alto Sinú malaria endemic area using a maximum entropy algorithm. Results showed that An. nuneztovari has the widest geographic distribution, occupying almost the entire study region; this niche breadth is probably related to the ability of this species to colonize both, natural and disturbed environments. The model for An. darlingi showed that most suitable localities for this species in Bajo Cauca were along the Cauca and Nechí river. The riparian ecosystems in this region and the potential for rapid adaptation by this species to novel environments, may favor the establishment of populations of this species. Apparently, the three main Colombian Anopheles vector species in this endemic area do not occupy environments either with high seasonality, or with low seasonality and high NDVI values. Estimated overlap in geographic space between An. nuneztovari and An. albimanus indicated broad spatial and environmental similarity between these species. An. nuneztovari has a broader niche and potential distribution. Dispersal ability of these species and their ability to occupy diverse environmental situations may facilitate sympatry across many environmental and geographic contexts. These model results may be useful for the design and implementation of malaria species-specific vector control interventions optimized for this important malaria region.

Within outlying mean indexes: refining the OMI analysis for the realized niche decomposition.

The ecological niche concept has regained interest under environmental change (e.g., climate change, eutrophication, and habitat destruction), especially to study the impacts on niche shift and conservatism. Here, we propose the within outlying mean indexes (WitOMI), which refine the outlying mean index (OMI) analysis by using its properties in combination with the K-select analysis species marginality decomposition. The purpose is to decompose the ecological niche into subniches associated with the experimental design, i.e., taking into account temporal and/or spatial subsets. WitOMI emphasize the habitat conditions that contribute (1) to the definition of species’ niches using all available conditions and, at the same time, (2) to the delineation of species’ subniches according to given subsets of dates or sites. The latter aspect allows addressing niche dynamics by highlighting the influence of atypical habitat conditions on species at a given time and/or space. Then, (3) the biological constraint exerted on the species subniche becomes observable within Euclidean space as the difference between the existing fundamental subniche and the realized subniche. We illustrate the decomposition of published OMI analyses, using spatial and temporal examples. The species assemblage’s subniches are comparable to the same environmental gradient, producing a more accurate and precise description of the assemblage niche distribution under environmental change. The WitOMI calculations are available in the open-access R package “subniche.”

Modeling and mapping the current and future climatic-niche of endangered Himalayan musk deer

Identification of geographical space enveloped by suitable climatic conditions (i.e., climatic niche) that support species survival over space and time is crucial in conservation biogeography. Numerous algorithms (e.g., Maxent, GARP) with increasing accuracy have been devised and are being employed to overcome the challenges of forecasting climatic niche of species with incomplete information. The current study was conducted to map the distribution of current and future climatic niche of endangered Himalayan musk deer, a species endemic to Asia. Maxent and GARP modeling algorithms were individually employed to forecast current and future climatic niche of the species using randomly collected occurrence records of the species and bioclimatic variables with 30″ resolution from ‘WorldClim’ datasets. Both the modeling processes performed optimally with regard to AUC and TSS values and forecasted an increase/expansion of climatically-suitable geographical space in the future. A final climatic niche distribution map was produced by combining the binary maps generated from each of the processes to produce a relatively realistic and potentially accurate distribution of climatic niche of the species over space and time. Conservation of forecasted suitable geographical space is recommended and future survey efforts for potentially unexplored populations of the species in the forecasted suitable area are suggested.

Evaluating Ecological Niche Models: A Comparison Between Maxent and GARP for Predicting Distribution of Hevea brasiliensis in India

Selection of appropriate ecological niche model for predicting species niche distribution has been a challenge considering the type of species and input variables. Therefore, two ecological niche modelling approaches (Maxent and GARP) are employed to predict the present distribution of a planted species (Hevea brasiliensis Muell. Arg.) in two bio-geographical regions of India: Western Ghats (WG) and North east (NE) regions. The difference between two approaches is in the algorithm and kinds of species data (presence-only or presence and absence) used for model training. GARP over-estimates were observed more in NE as compared to that of WG. Maxent predicts Hevea distribution more accurately in both regions as it considers presence-only data, which appears to be more accurate for this species. The over-prediction of Hevea niche distribution by GARP especially in NE may be attributed to inaccurate and insufficient ‘absence data’ as compared to ‘presence data’. The model accuracy estimator, AUC failed to attribute the difference in model predictability between Maxent and GARP, whereas partial-AUC is found to be better estimator of model spatial accuracy. Therefore, Maxent is found to be more appropriate model for predicting the niche distribution of a plantation species like Hevea.

Predicting American Oystercatcher (Haematopus palliatus) Breeding Distribution in an Urbanized Coastal Ecosystem Using Maximum Entropy Modeling

Abstract. Species distribution modeling has seen widespread use in ecology and conservation over the past two decades, and as a result many questions regarding the predictive capabilities of new techniques have been raised. One modeling approach that has gained popularity is Maxent, which uses presence-only data to model species distributions. Although Maxent is ordinarily used to model a species' fundamental niche at large scales (e.g., continental-scale), this technique was used to develop a predictive model for the realized niche and local breeding distribution of American Oystercatchers (Haematopus palliatus) in coastal New Jersey, USA. The transferability of the predictive model to locations outside training areas was examined in an effort to locate new breeding populations in previously unsurveyed areas. Initial model validation indicated that Maxent performed well, exhibiting good discrimination ability based on analyses of both training data (AUC = 0.95) and test data (AUC = 0.91). Ground surveys ...

Climatic niche shift of aquatic plant invaders between native and invasive ranges: a test using 10 species across different biomes on a global scale

Environmental niche conservatism defines a concept, stating that species could live in the same environmental condition in both native and invasive ranges. Niche modeling often used this as basis for the prediction of the range of invasive plants. However, it is debatable whether environmental niches of invasive plant species are conserved or shift between native and invasive ranges. Only few studies have investigated such a shift in aquatic plant invaders (APIs) on a meaningful global scale. Environmental niche modeling was used to project climatic niche distributions of 10 APIs based both on the native range and the invasive range of species. We found that niche shifts of APIs between native and invasive ranges may occur throughout the world. Moreover, we found niche shifts of APIs between native and invasive ranges across different biomes. The largest climatic niche shift was detected for Najas minor and the smallest for Alternanthera philoxeroides . For all 10 APIs, overlap between both ranges was maximal for large river deltas, while overlap was minimal for temperate floodplain rivers and wetlands. For APIs, the suitability of the climatic habitat was highest in temperate coastal rivers for invasive models in invasive ranges. More importantly, based on invasive models, climatic suitability was significantly higher for temperate coastal rivers and temperate floodplain rivers and wetlands in invasive ranges and compared to native models. We suggest to integrate climatic niches of both native and invasive ranges into projections of the global climatic niche distribution of APIs.

Twenty-first century approaches to ancient problems: Climate and society

By documenting how humans adapted to changes in their environment that are often much greater than those experienced in the instrumental record, archaeology provides our only deep-time laboratory for highlighting the circumstances under which humans managed or failed to find to adaptive solutions to changing climate, not just over a few generations but over the longue durée. Patterning between climate-mediated environmental change and change in human societies has, however, been murky because of low spatial and temporal resolution in available datasets, and because of failure to model the effects of climate change on local resources important to human societies. In this paper we review recent advances in computational modeling that, in conjunction with improving data, address these limitations. These advances include network analysis, niche and species distribution modeling, and agent-based modeling. These studies demonstrate the utility of deep-time modeling for calibrating our understanding of how climate is influencing societies today and may in the future.

Glacial refugia and the prediction of future habitat coverage of the South American lichen species Ochrolechia austroamericana.

The biogeographic history of lichenized fungi remains unrevealed because those organisms rarely fossilize due to their delicate, often tiny and quickly rotting thalli. Also the ecology and factors limiting occurrence of numerous taxa, especially those restricted in their distribution to tropical areas are poorly recognized. The aim of this study was to determine localization of glacial refugia of South American Ochrolechia austroamericana and to estimate the future changes in the coverage of its habitats using ecological niche modeling tools. The general glacial potential range of the studied species was wider than it is nowadays and its niches coverage decreased by almost 25% since last glacial maximum. The refugial areas were covered by cool and dry grasslands and scrubs and suitable niches in South America were located near the glacier limit. According to our analyses the further climate changes will not significantly influence the distribution of the suitable niches of O. austroamericana.

Transnational cult and/as neoliberalism: the liminal economies of anime fansubbers

This article will consider how two contested terms – the ‘transnational’ and ‘cult’ – can be brought into dialogue via a focus on English-language fansubbing labour. Testifying to translation’s ‘transformative’ cultifying capacities, anime fansubbers in the West operate in an imagined space between Japan and the United States. A third space of imagination rather than transnational flow per se becomes vital here. I will expand on this by considering how anime fansubbers’ labour can be conceptualized as liminal, intersecting ‘informal’ and ‘formal’ economies whilst at the same time performing transnational cult as a neoliberal supplement to industry practices. Rather than straightforwardly enacting ‘anti-mainstream’ difference, this imagined space is potentially one of competitive entrepreneurial practice and fan-branding, suggesting that aspects of fansubbing can be aligned with neoliberalism. The implication is that we need to consider transnational cult status more significantly in relation to niche and fan distribution, where both can be commercialized and/or linked to ‘mainstream’ values of branding and entrepreneurialism.

Ecological niche and species distribution modelling of sea stars along the Pacific Northwest continental shelf

AbstractAimPopulations of several sea star species were devastated by a disease in 2013–2014 from Alaska to Baja California. However, their exact distributions and ecological requirements are unknown and better knowledge could help identify populations that are at risk. This study aimed to assess patterns of distribution and determine ecological requirements of several sea star species affected by the disease.LocationContinental shelf from southern Washington State to northern California, USA.MethodsA large occurrence dataset (5385 data points) of 11 taxa was gathered from bottom trawl surveys and underwater video footage, along with data for 13 oceanographic and seafloor environmental parameters. Species distribution modelling (Maxent) and ecological niche (outlying mean index) analyses were applied to these biotic and abiotic datasets.ResultsEach species showed contrasting ecological niches and modelled distributions, the main explanatory factors being depth, temperature, salinity, sediment mean grain size and the presence of rocky outcrops. Despite these species being recorded from Alaska to California, some sea stars showed very narrow distributions, whereas other taxa were widely distributed in the whole area.Main conclusionsThe modelled ecological niches and distributions of these 11 sea star taxa showed a high degree of differentiation. Because intertidal and shallow subtidal populations were drastically affected by the 2013–2014 disease, recovery will depend on health of subtidal populations and the ability of the species to disperse and recolonize shallower areas. Our study will serve as a useful reference of the species distributions before the disease started. This distributional data and assessment of influential environmental factors will be valuable for future predictions or studies of the effects of bottom‐contact ocean‐use activities on sea star species as well as the effects of climate change. Understanding habitat conditions favourable for these species may be helpful in managing population recovery following disease outbreaks or other catastrophic events.

Распределение экологических ниш иксодофауны Canis lupus familiaris на территории Ульяновской области

Распределение экологических ниш иксодофауны Canis lupus familiaris на территории Ульяновской области

The impact of seasonality on niche breadth, distribution range and species richness: a theoretical exploration of Janzen's hypothesis.

Being invoked as one of the candidate mechanisms for the latitudinal patterns in biodiversity, Janzen's hypothesis states that the limited seasonal temperature variation in the tropics generates greater temperature stratification across elevations, which makes tropical species adapted to narrower ranges of temperatures and have lower effective dispersal across elevations than species in temperate regions. Numerous empirical studies have documented latitudinal patterns in species elevational ranges and thermal niche breadths that are consistent with the hypothesis, but the theoretical underpinnings remain unclear. This study presents the first mathematical model to examine the evolutionary processes that could back up Janzen's hypothesis and assess the effectiveness of limited seasonal temperature variation to promote speciation along elevation in the tropics. Results suggest that trade-offs in thermal tolerances provide a mechanism for Janzen's hypothesis. Limited seasonal temperature variation promotes gradient speciation not due to the reduction in gene flow that is associated with narrow thermal niche, but due to the pleiotropic effects of more stable divergent selection of thermal tolerance on the evolution of reproductive incompatibility. The proposed modelling approach also provides a potential way to test a speciation model against genetic data.

Realized climate niche breadth varies with population trend and distribution in North American birds

AbstractAimEcological niche theory states that realized niche breadth should increase with population growth. This relationship has been studied extensively in the context of density‐dependent habitat selection, and there is evidence that animal populations at higher density occupy a wider range of vegetation types. To our knowledge, no previous studies have investigated the relationship between population growth and climate niche breadth (i.e. the range of climatic conditions occupied). Here we aim to estimate the influence of population trend, as well as changes in distribution, on realized climate niche breadth.LocationNorth America.MethodsWe estimated changes in realized climate niche breadth and distribution between 1980 and 2012 for 46 bird species using data from the North American Breeding Bird Survey (BBS) and standard ecological niche modelling techniques. We analysed changes in niche breadth in relation to population trends and distributional changes from the BBS for these same species.ResultsChanges in realized climate niche breadth were significantly and positively associated with population growth, as reflected by BBS population trends, and with changes in distributional extent. Using variance partitioning, we showed that 44.2% of the variation in change in niche breadth can be explained by population trend, and that roughly half of this was independent of changes in distribution.ConclusionsRealized climate niche breadth is variable on an ecological time‐scale as a function of population trend. Mechanisms associated with changes in distribution and those acting within current species range limits appear to be equally important in driving this relationship. Observed changes in niche breadth may violate distribution modelling assumptions of niche conservatism. Studying how population growth influences realized climate niche breadth is therefore important for understanding dynamic species distributions, responses to climate change and our ability to model future species distributions.

Climate Change Influences on the Global Potential Distribution of Bluetongue Virus.

The geographic distribution of arboviruses has received considerable attention after several dramatic emergence events around the world. Bluetongue virus (BTV) is classified among category “A” diseases notifiable to the World Organization of Animal Health (OIE), and is transmitted among ruminants by biting midges of the genus Culicoides. Here, we developed a comprehensive occurrence data set to map the current distribution, estimate the ecological niche, and explore the future potential distribution of BTV globally using ecological niche modeling and based on diverse future climate scenarios from general circulation models (GCMs) for four representative concentration pathways (RCPs). The broad ecological niche and potential geographic distribution of BTV under present-day conditions reflected the disease’s current distribution across the world in tropical, subtropical, and temperate regions. All model predictions were significantly better than random expectations. As a further evaluation of model robustness, we compared our model predictions to 331 independent records from most recent outbreaks from the Food and Agriculture Organization Emergency Prevention System for Transboundary Animal and Plant Pests and Diseases Information System (EMPRES-i); all were successfully anticipated by the BTV model. Finally, we tested ecological niche similarity among possible vectors and BTV, and could not reject hypotheses of niche similarity. Under future-climate conditions, the potential distribution of BTV was predicted to broaden, especially in central Africa, United States, and western Russia.