Variability In Species Distribution Research Articles

Prospective modelling of operational offshore wind farms on the distribution of marine megafauna in the southern North Sea

Intense development of Offshore Wind Farms (OWFs) has occurred in the North Sea with several more farms planned for the near future. These OWFs pose a threat to marine megafauna stressing the need to mitigate the impact of human activities. To help mitigate impacts, the Before After Gradient (BAG) design was proposed. We explored the use of the BAG method on megafauna sightings recorded at different distances from OWFs in the southern North Sea. We predicted intra-annual variability in species distribution, then correlated species distribution with the presence of operational OWFs and investigated the potential impact the operation of prospective OWFs may have on species distribution. Four patterns of intra-annual variability were predicted: species most abundant in spring, in winter, in both spring and winter, or all year round. We recommend that future OWF constructions be planned in summer and early fall to minimise impact on cetaceans and that offshore areas off northern France and Belgium be avoided to minimise impact on seabirds. Our prospective analysis predicted a decreased density for most species with the operation of prospective OWFs. Prospective approaches, using e.g. a BAG design, are paramount to inform species conservation as they can forecast the likely responses of megafauna to anthropogenic disturbances.

Community confounding in joint species distribution models

Joint species distribution models have become ubiquitous for studying species-environment relationships and dependence among species. Accounting for community structure often improves predictive power, but can also affect inference on species-environment relationships. Specifically, some parameterizations of joint species distribution models allow interspecies dependence and environmental effects to explain the same sources of variability in species distributions, a phenomenon we call community confounding. We present a method for measuring community confounding and show how to orthogonalize the environmental and random species effects in suite of joint species distribution models. In a simulation study, we show that community confounding can lead to computational difficulties and that orthogonalizing the environmental and random species effects can alleviate these difficulties. We also discuss the inferential implications of community confounding and orthogonalizing the environmental and random species effects in a case study of mammalian responses to the Colorado bark beetle epidemic in the subalpine forest by comparing the outputs from occupancy models that treat species independently or account for interspecies dependence. We illustrate how joint species distribution models that restrict the random species effects to be orthogonal to the fixed effects can have computational benefits and still recover the inference provided by an unrestricted joint species distribution model.

Erratum: Allergenic Pollen Calendar in Korea Based on Probability Distribution Models and Up-to-Date Observations

This corrects the article on p. 259 in vol. 12, PMID: 32009321.

Allergenic Pollen Calendar in Korea Based on Probability Distribution Models and Up-to-Date Observations.

PurposeThe pollen calendar is the simplest forecasting method for pollen concentrations. As pollen concentrations are liable to seasonal variations due to alterations in climate and land-use, it is necessary to update the pollen calendar using recent data. To attenuate the impact of considerable temporal and spatial variability in pollen concentrations on the pollen calendar, it is essential to employ a new methodology for its creation.MethodsA pollen calendar was produced in Korea using data from recent observations, and a new method for creating the calendar was proposed, considering both risk levels and temporal resolution of pollen concentrations. A probability distribution was used for smoothing concentrations and determining risk levels. Airborne pollen grains were collected between 2007 and 2017 at 8 stations; 13 allergenic pollens, including those of alder, Japanese cedar, birch, hazelnut, oak, elm, pine, ginkgo, chestnut, grasses, ragweed, mugwort and Japanese hop, were identified from the collected grains.ResultsThe concentrations of each pollen depend on locations and seasons due to large variability in species distribution and their environmental condition. In the descending order of concentration, pine, oak and Japanese hop pollens were found to be the most common in Korea. The pollen concentrations were high in spring and autumn, and those of oak and Japanese hop were probably the most common cause of allergy symptoms in spring and autumn, respectively. High Japanese cedar pollen counts were observed in Jeju, while moderate concentrations were in Jeonju, Gwangju and Busan.ConclusionsA new methodology for the creation of a pollen calendar was developed to attenuate the impact of large temporal and spatial variability in pollen concentrations. This revised calendar should be available to the public and allergic patients to prevent aggravation of pollen allergy.

Expansion of Protected Areas under Climate Change: An Example of Mountainous Tree Species in Taiwan

Tree species in mountainous areas are expected to shift their distribution upward in elevation in response to climate change, calling for a potential redesign of existing protected areas. This study aims to predict whether or not the distributions of two high-mountain tree species, Abies (Abies kawakamii) and Tsuga (Tsuga chinensis var. formosana), will significantly shift upward due to temperature change, and whether current protected areas will be suitable for conserving these species. Future temperature change was projected for 15 different future scenarios produced from five global climate models. Shifts in Abies and Tsuga distributions were then predicted through the use of species distribution models (SDMs) which included occurrence data of Abies and Tsuga, as well as seasonal temperature, and elevation. The 25 km × 25 km downscaled General Circulation Model (GCMs) data for 2020–2039 produced by the Taiwan Climate Change Projection and Information Platform was adopted in this study. Habitat suitability in the study area was calculated using maximum entropy model under different climatic scenarios. A bootstrap method was applied to assess the parameter uncertainty of the maximum entropy model. In comparison to the baseline projection, we found that there are significant differences in suitable habitat distributions for Abies and Tsuga under seven of the 15 scenarios. The results suggest that mountainous ecosystems will be substantially impacted by climate change. We also found that the uncertainty originating from GCMs and the parameters of the SDM contribute most to the overall level of variability in species distributions. Finally, based on the uncertainty analysis and the shift in habitat suitability, we applied systematic conservation planning approaches to identify suitable areas to add to Taiwan’s protected area network.

Epidemiology and outcomes of invasive candidiasis due to non-albicans species of Candida in 2,496 patients: data from the Prospective Antifungal Therapy (PATH) registry 2004-2008.

This analysis describes the epidemiology and outcomes of invasive candidiasis caused by non-albicans species of Candida in patients enrolled in the Prospective Antifungal Therapy Alliance (PATH Alliance) registry from 2004 to 2008. A total of 2,496 patients with non-albicans species of Candida isolates were identified. The identified species were C. glabrata (46.4%), C. parapsilosis (24.7%), C. tropicalis (13.9%), C. krusei (5.5%), C. lusitaniae (1.6%), C. dubliniensis (1.5%) and C. guilliermondii (0.4%); 111 infections involved two or more species of Candida (4.4%). Non-albicans species accounted for more than 50% of all cases of invasive candidiasis in 15 of the 24 sites (62.5%) that contributed more than one case to the survey. Among solid organ transplant recipients, patients with non-transplant surgery, and patients with solid tumors, the most prevalent non-albicans species was C. glabrata at 63.7%, 48.0%, and 53.8%, respectively. In 1,883 patients receiving antifungal therapy on day 3, fluconazole (30.5%) and echinocandins (47.5%) were the most frequently administered monotherapies. Among the 15 reported species, 90-day survival was highest for patients infected with either C. parapsilosis (70.7%) or C. lusitaniae (74.5%) and lowest for patients infected with an unknown species (46.7%) or two or more species (53.2%). In conclusion, this study expands the current knowledge of the epidemiology and outcomes of invasive candidiasis caused by non-albicans species of Candida in North America. The variability in species distribution in these centers underscores the importance of local epidemiology in guiding the selection of antifungal therapy.

Epidemiology of Candidemia in Latin America: A Laboratory-Based Survey

BackgroundThe epidemiology of candidemia varies depending on the geographic region. Little is known about the epidemiology of candidemia in Latin America.MethodsWe conducted a 24-month laboratory-based survey of candidemia in 20 centers of seven Latin American countries. Incidence rates were calculated and the epidemiology of candidemia was characterized.ResultsAmong 672 episodes of candidemia, 297 (44.2%) occurred in children (23.7% younger than 1 year), 36.2% in adults between 19 and 60 years old and 19.6% in elderly patients. The overall incidence was 1.18 cases per 1,000 admissions, and varied across countries, with the highest incidence in Colombia and the lowest in Chile. Candida albicans (37.6%), C. parapsilosis (26.5%) and C. tropicalis (17.6%) were the leading agents, with great variability in species distribution in the different countries. Most isolates were highly susceptible to fluconazole, voriconazole, amphotericin B and anidulafungin. Fluconazole was the most frequent agent used as primary treatment (65.8%), and the overall 30-day survival was 59.3%.ConclusionsThis first large epidemiologic study of candidemia in Latin America showed a high incidence of candidemia, high percentage of children, typical species distribution, with C. albicans, C. parapsilosis and C. tropicalis accounting for the majority of episodes, and low resistance rates.

Colonization of the oral cavity by yeasts in patients with chronic renal failure undergoing hemodialysis

To determine the frequency of yeast in the oral cavity of patients with chronic renal failure, undergoing hemodialysis (PCRFH); identification and antifungal susceptibility profile of yeast and demographic profile of patients. We performed mouthwash in 146 PCRFH; the rinse fluid was collected and cultured, yeasts grown were identified by phenotypic and molecular methods. The antifungal susceptibility profile was determined against nystatin, amphotericin B, fluconazole, voriconazole, and caspofungin based in Clinical and Laboratory Standards Institute (document M27-A3). Positive culture was observed in 39% of patients, of whom 53% were women; the median of dialysis time was 2.9 years. The age of the colonized patients varied between 26 and 84 years, with a median of 52.5 years. PCRFH over 45 years were significantly more colonized (P = 0.0108) as well as denture wearers (84.0%). We isolated 81 yeasts, predominantly Candida albicans (63%) followed by Candida glabrata. In general, yeasts were sensitive to the evaluated antifungal agents, but there was significant variation in the minimum inhibitory concentration, especially among non-C. albicans Candida (NCAC) compared to fluconazole, caspofungin, and amphotericin B. NCAC required significantly higher concentrations of fluconazole (P < 0.01). The rate of colonization by yeasts in PCRFH was high, and there was variability in species distribution and antifungal susceptibility profile. These results are little known in this group of patients and are important for controlling the risk of developing invasive fungal infections.

Do vegetation patch spatial patterns disrupt the spatial organization of plant species?

The mechanisms that structure plant diversity and generate long-range correlated spatial patterns have important implications for the conservation of fragmented landscapes. The ability to disperse and persist influences a plant species’ capacity for spatial organization, which can play a critical role in structuring plant diversity in metacommunities. This study examined the spatial patterns of species diversity within a network of patches in Cabo de Gata Natural Park, southeastern Spain. The objectives were to understand how the spatial heterogeneity of species composition (beta diversity) varies in a structured landscape, and how the long-range spatial autocorrelation of plant species is affected by the spatial configuration of patches. The mechanisms underlying the spatial distribution of plants acted at two scales. Between patches, spatial variation in species distributions was greater than that expected based on spatial randomization, which indicated that movement among patches was restricted. Within patches, diffusion processes reduced spatial variability in species distributions, and the effect was more prominent in large patches. Small patch size negatively influenced the long-range spatial autocorrelation of characteristic species, whereas inter-patch distance had a stronger effect on species frequency than it had on the disruption of spatial organized patterns. The long-range spatial autocorrelation was evaluated based on the dispersal abilities of the species. Among the 106 species evaluated, 39% of the woody species, 17% of the forbs, and 12% of the grasses exhibited disrupted long-range spatial autocorrelation where patches were small. The species that are more vulnerable to the effects of fragmentation tended to be those that have restricted dispersal, such as those that have short-range dispersal (atelechoric), e.g., Phlomis purpurea, Cistus albidus, Teucrium pseudochamaepytis, Brachypodium retusum, and the ballistic species, Genista spartioides. Helianthemum almeriense is another vulnerable species that has actively restricted dispersal (antitelechory), which is common in arid regions. Wind dispersers such as Launaea lanifera were less vulnerable to the effects of fragmentation. Long-distance dispersers whose persistence depends on facilitative interactions with other individuals, e.g., allogamous species such as Thymus hyemalis, Ballota hirsuta, and Anthyllis cytisoides, exhibit disrupted long-range spatial autocorrelation when patch size is reduced.

Relationship between benthic insects (Ephemeroptera, Plecoptera, Coleoptera, Trichoptera) and temperature in small and medium-sized streams in Germany: A multivariate study

Benthic insect communities (Ephemeroptera, Plecoptera, Coleoptera, Trichoptera) were studied together with water temperature and environmental parameters in streams between June 2000 and June 2001. The sampling area consisted of 20 sites in small and medium-sized streams located in the lower mountainous area of Central Europe. Temperature was recorded nearly continuously and several physicochemical and environmental variables were assessed. Macroinvertebrates were sampled both in spring and summer. Data-sets of species abundance and occurrence were analysed using multivariate techniques and were correlated to the thermal and environmental conditions of the streams. The temperature preferences of the species were compared to published data-sets on their autecological characteristics. Up to 29% of the variability in the Ephemeroptera, Plecoptera, Trichoptera and Coleoptera community was explained by summer temperature variation in the data-sets for both small and medium-sized streams. A smaller, but significant part of the variability in species distribution was explained by conductivity, substratum type, and the percent coverage of local riparian forest. Compared to small streams, temperature was less important for the macroinvertebrate composition in medium-sized streams. This result is likely due to the more tolerant, eurythermic species composition in larger streams. A total of 33 Ephemeroptera, Plecoptera, Coleoptera and Trichoptera taxa were positively correlated and 28 taxa were negatively correlated to summer temperature patterns. The temperature preferences of taxa considered in this study were related to species traits, such as egg dormancies and life cycle plasticity.

Patterns of liana diversity in tropical evergreen forests of peninsular India

The quantitative liana inventories made in five peninsular Indian independent forest sites, distributed in the Western Ghats, Eastern Ghats and on the Coromandel coast, were examined particularly with reference to site altitude and forest stature. Liana diversity totaled 148 species in 101 genera of 47 families, in a total sample of 47 ha. The coefficient of variability in species distribution among the five sites was used to identify an oligarchy in liana species by taking 55 abundant species from the species pool. Ordination analysis, based on presence–absence as well as relative density of liana species indicated a geographical differentiation among the five sites in both the ordinations with respect to site altitude. Liana density (stems>1.6 cm diameter) decreased with increasing altitude, whereas richness was highest at intermediate elevations. The mean liana density across the forest sites showed a weak negative correlation with forest stature. The lianas encountered in the five study sites fell under six climber types, of which twining was the chief climbing mechanism, both in terms of species diversity and density, and tendril climbers were more abundant in dry evergreen forests than in the wet evergreen forests. In liana diaspore dispersal modes, the majority of evergreen forest species possessed animal dispersal guilds, whereas wind-dispersal was prevalent in semi-evergreen and dry evergreen forests.

Dominance, diversity and distribution of lianas in Yasuní, Ecuador: who is on top?

Lianas of Yasuní National Park and the Huaorani Ethnic Reserve, Ecuador were sampled using 0.2-ha subsamples from 12 1-ha plots. Using surveys and herbarium collections, the total species richness of lianas in the park and reserve is estimated to be close to 500 species. Terra firme habitats are significantly more species rich than floodplain habitats, but density of stems is not significantly different between habitats. The most abundant liana species is Machaerium cuspidatum Kuhlm. &amp; Hoehne (Fabaceae) in both floodplain and terra firme habitats, representing more than 10% of all stems in census plots. Analysis of rarity indicates that none of the liana species encountered on the 12 plots is rare in terms of geographic range, and many species are not rare in terms of population size or habitat specificity. The rank order of abundance, combined with the coefficient of variability in species distribution among plots, is used to identify the 38 species (an oligarchy) that dominate forests in Yasuní.

Variability of zonation patterns in temperate microtidal Uruguayan beaches with different morphodynamic types

MEPS Marine Ecology Progress Series Contact the journal Facebook Twitter RSS Mailing List Subscribe to our mailing list via Mailchimp HomeLatest VolumeAbout the JournalEditorsTheme Sections MEPS 160:197-207 (1997) - doi:10.3354/meps160197 Variability of zonation patterns in temperate microtidal Uruguayan beaches with different morphodynamic types Luis Giménez*, Beatriz Yannicelli Facultad de Ciencias, Sección Oceanografía, Tristán Narvaja 1674, 11200 Montevideo, Uruguay *Present address: Biologische Anstalt Helgoland, Meeresstation Helgoland, Postfach 180, D-27483 Helgoland, Germany Early studies on sandy beach zonation patterns have shown rather rigid schemes. Recent work has suggested that zonation changes with morphodynamic type and, in dissipative beaches, it also changes through time. This last finding leads to the conclusion that at least 1 yr of study is necessary to understand zonation patterns in dissipative sandy beaches. Here we report a 1 yr study (from March 1994 to March 1995) of 4 microtidal beaches with different morphodynamic types situated on the Atlantic coast of Uruguay. We show that zonation patterns (number of zones or belts) can change through time regardless of beach type. However, the morphodynamic characteristics of the beach seem to affect how frequently the zonation pattern can change by fusion or subdivision of zones, and which zones are involved in those processes. In beaches with flat slopes (toward the dissipative extremity), the lower zones were frequently fused and divided. The same occurred with the medium and upper zones in the beaches with steeper slopes (towards the reflective extremity). Our results suggest that spatial variability of the macrofauna is related to variability in the position of the swash zone, which in turn depends on beach slope and width. Variability of species distribution would also depend on morphological adaptations of organisms to move in such environments. We suggest 2 mechanisms of species movement to explain the variability in species distribution observed in this study: Swash Mediated Active Movement (SMAM) and Autonomous Active Movement (AAM). The first mechanism involves both an active and a passive component. AAM is independent of swash movements and affects species distribution on the upper levels of the beach. Sandy beaches · Seasonal variability · Zonation pattern · Morphodynamic types · Uruguay Full text in pdf format PreviousNextExport citation RSS - Facebook - Tweet - linkedIn Cited by Published in MEPS Vol. 160. Publication date: December 15, 1997 Print ISSN:0171-8630; Online ISSN:1616-1599 Copyright © 1997 Inter-Research.

Neutral models for the spatial distribution of organisms: implications for paleoenvironmental interpretation

A fundamental assumption of paleoecology is that spatial variability in species distributions and associations reflect underlying spatial variability in physical environmental parameters. For example, gradients in species composition are usually interpreted as relating to gradients in variables such as water depth, temperature, or soil moisture. Numerous examples support the idea that when an environmental gradient is known to exist, there is a corresponding non-random community gradient. We suggest, however, that the reverse may not necessarily be true; i.e., a community gradient may exist even in the absence of an underlying physical gradient.We have developed a series of models for the spatial distribution of organisms on landscapes (spatially heterogenous areas ranging in size from hectares to many square kilometers). In these models, a landscape is represented by a two-dimensional lattice, where each node of the lattice is a habitat site. Each habitat site is randomly assigned to one of a set of multiple habitat types (generally 3-6). A map of the lattice would thus show a random distribution of habitat types.Habitat sites are competed for by sessile organisms that complete their life cycle in one time step (e.g., annual plants). “Seeds” are spread to a site from its eight next nearest neighbors. Each species' seeds successfully germinate on only a subset of the available habitat types (its “niche”), with one or more types being optimal (highest probability of germination). These subsets can overlap, so that different species can potentially occupy the same site. The probability of a given species taking over a site depends on the number of neighboring sites it occupies and whether the site is optimal. A site can be taken over by a suboptimal species if it locally more abundant.Each organism's niche directly controls its ability to spread (“percolate”) through the landscape. Under the next-nearest neighbor rule, a species must be able to live on &gt;40% of all possible sites in order to spread. Competition, by reducing the number of available sites, may prevent a species from reaching all habitable sites, even those that are optimal.In one model, five habitat types are randomly distributed on a 201 × 201 matrix. Five species, each of which has an optimal habitat corresponding to one of the five habitats but can live on two additional habitats, are randomly introduced at one edge of the map and are allowed to spread. When the resulting distribution maps are examined, preferred species associations and gradients are observed, although there is no underlying habitat gradient. Instead, the observed patterns result from a combination of biotic interactions and historical contingencies, such as founder effects.This and related models show how random processes can produce biotic patterns in the absence of environmental patterns. They provide appropriate neutral models for the interpretation of paleoenvironmental patterns based solely on species distributions.