Potential Geographic Distribution of the Novel Avian-Origin Influenza A (H7N9) Virus

Background In late March 2013, a new avian-origin influenza virus emerged in eastern China. This H7N9 subtype virus has since infected 240 people and killed 60, and has awakened global concern as a potential pandemic threat. Ecological niche modeling has seen increasing applications as a useful tool in mapping geographic potential and risk of disease transmission. Methodology/Principals We developed two datasets based on seasonal variation in Normalized Difference Vegetation Index (NDVI) from the MODIS sensor to characterize environmental dimensions of H7N9 virus. One-third of well-documented cases was used to test robustness of models calibrated based on the remaining two-thirds, and model significance was tested using partial ROC approaches. A final niche model was calibrated using all records available. Conclusions/Significance Central-eastern China appears to represent an area of high risk for H7N9 spread, but suitable areas were distributed more spottily in the north and only along the coast in the south; highly suitable areas also were identified in western Taiwan. Areas identified as presenting high risk for H7N9 spread tend to present consistent NDVI values through the year, whereas unsuitable areas show greater seasonal variation.No current funding sources were specifically designate for this study, however, partial support was from the talent introduction program award to GZ in Tianjin Normal University (5RL127). No additional funding was received for this study. The funder had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript

An evaluation of transferability of ecological niche models

Ecological niche modeling (ENM) is used widely to study species’ geographic distributions. ENM applications frequently involve transferring models calibrated with environmental data from one region to other regions or times that may include novel environmental conditions. When novel conditions are present, transferability implies extrapolation, whereas, in absence of such conditions, transferability is an interpolation step only. We evaluated transferability of models produced using 11 ENM algorithms from the perspective of interpolation and extrapolation in a virtual species framework. We defined fundamental niches and potential distributions of 16 virtual species distributed across Eurasia. To simulate real situations of incomplete understanding of species’ distribution or existing fundamental niche (environmental conditions suitable for the species contained in the study area; N* F ), we divided Eurasia into six regions and used 1–5 regions for model calibration and the rest for model evaluation. The models produced with the 11 ENM algorithms were evaluated in environmental space, to complement the traditional geographic evaluation of models. None of the algorithms accurately estimated the existing fundamental niche (N* F ) given one region in calibration, and model evaluation scores decreased as the novelty of the environments in the evaluation regions increased. Thus, we recommend quantifying environmental similarity between calibration and transfer regions prior to model transfer, providing an avenue for assessing uncertainty of model transferability. Different algorithms had different sensitivity to completeness of knowledge of N* F , with implications for algorithm selection. If the goal is to reconstruct fundamental niches, users should choose algorithms with limited extrapolation when N* F is well known, or choose algorithms with increased extrapolation when N* F is poorly known. Our assessment can inform applications of ecological niche modeling transference to anticipate species invasions into novel areas, disease emergence in new regions, and forecasts of species distributions under future climate conditions

Mapping the potential distribution of the schistosomiasis intermediate host Biomphalaria straminea in China

Biomphalaria straminea is native to Brazil but has established a population in Guangdong Province China. Its potential of expanding and transmitting Schistosoma mansoni is of great concern. We seek to map S. mansoni transmission potential by predicting ecological dimensions and potential distributions of B. straminea using state-of-the-art ecological niche model approaches. Two environmental datasets were selected to fit individual and ensemble niche models, together with the evaluation of niche conservatism during B. straminea invasion in China. A small area is still occupied by the introduced population compared to that in Brazil. A vast space with suitable climate remains unfilled and might be available to B. straminea. Contrasting results of niche conservatism evaluation were attained based on the two environmental datasets. The coastal areas in southern China, together with south-western Yunnan and southern Hainan and Taiwan were consistent supported by multiple model approaches, showing high climate suitability for B. straminea. Attention should be paid to the possibility of S. mansoni epidemic in these identified areas, as high pressure due to propagation and future climate change may further complicate conditions. Our results call for rigorous monitoring and supervising along these areas in China

ENM2020 : A FREE ONLINE COURSE AND SET OF RESOURCES ON MODELING SPECIES NICHES AND DISTRIBUTIONS

The field of distributional ecology has seen considerable recent attention, particularly surrounding the theory, protocols, and tools for Ecological Niche Modeling (ENM) or Species Distribution Modeling (SDM). Such analyses have grown steadily over the past two decades-including a maturation of relevant theory and key concepts-but methodological consensus has yet to be reached. In response, and following an online course taught in Spanish in 2018, we designed a comprehensive English-language course covering much of the underlying theory and methods currently applied in this broad field. Here, we summarize that course, ENM2020, and provide links by which resources produced for it can be accessed into the future. ENM2020 lasted 43 weeks, with presentations from 52 instructors, who engaged with >2500 participants globally through >14,000 hours of viewing and >90,000 views of instructional video and question-and-answer sessions. Each major topic was introduced by an "Overview" talk, followed by more detailed lectures on subtopics. The hierarchical and modular format of the course permits updates, corrections, or alternative viewpoints, and generally facilitates revision and reuse, including the use of only the Overview lectures for introductory courses. All course materials are free and openly accessible (CC-BY license) to ensure these resources remain available to all interested in distributional ecology.Peer reviewe

Potential Geographic Distribution of Brown Marmorated Stink Bug Invasion (Halyomorpha halys)

BACKGROUND: The Brown Marmorated Stink Bug (BMSB), Halyomorpha halys (Stål) (Hemiptera: Pentatomidae), native to Asia, is becoming an invasive species with a rapidly expanding range in North America and Europe. In the US, it is a household pest and also caused unprecedented damage to agriculture crops. Exploring its climatic limits and estimating its potential geographic distribution can provide critical information for management strategies. METHODOLOGY/PRINCIPALS: We used direct climate comparisons to explore the climatic niche occupied by native and invasive populations of BMSB. Ecological niche modelings based on the native range were used to anticipate the potential distribution of BMSB worldwide. Conversely, niche models based on the introduced range were used to locate the original invasive propagates in Asia. Areas with high invasion potential were identified by two niche modeling algorithms (i.e., Maxent and GARP). CONCLUSIONS/SIGNIFICANCE: Reduced dimensionality of environmental space improves native model transferability in the invade area. Projecting models from invasive population back to native distributional areas offers valuable information on the potential source regions of the invasive populations. Our models anticipated successfully the current disjunct distribution of BMSB in the US. The original propagates are hypothesized to have come from northern Japan or western Korea. High climate suitable areas at risk of invasion include latitudes between 30°-50° including northern Europe, northeastern North America, southern Australia and the North Island of New Zealand. Angola in Africa and Uruguay in South America also showed high climate suitability

Known H7N9 virus cases across eastern China (blue dots) overlaid on the bioNDVI layers (left), and principal components analysis visualizations (right) of environmental variation across eastern China.

<p>Simplified province names were overlaid on the map (LN: Liaoning, SD: Shandong, HEN: Henan, JS: Jiangsu, AH: Anhui, HB: Hubei, SH: Shanghai, ZJ: Zhejiang, JX: Jiangxi, HUN: Hunan, FJ: Fujian, GD: Guangdong, TW: Taiwan).</p

Model performance in anticipating the geographic distribution of independent latitude (left) and longitude (right) records using the principal component axes.

<p>Blue dots were sites used to calibrate the niche model, black crosses indicate independent testing records (inner panels), dark red suggests high suitability.</p

Final suitability model predictions for H7N9 across eastern China using principal components (top row) and the bioNDVI dataset (bottom row).

<p>Right-hand panels show greater detail for the areas indicated in the left-hand panels; dark red indicates zones of high suitability.</p

Visualization of year-round trends in MODIS NDVI greenness indices in modeled unsuitable (top) and suitable (bottom) areas for H7N9 virus based on a 10% omission threshold.

<p>Visualization of year-round trends in MODIS NDVI greenness indices in modeled unsuitable (top) and suitable (bottom) areas for H7N9 virus based on a 10% omission threshold.</p