Geographical distribution of two major quarantine fruit flies (Bactrocera minax Enderlein and Bactrocera dorsalis Hendel) in Sichuan Basin based on four SDMs

Both Bactrocera minax and Bactrocera dorsalis are phytophagous insects, and their larvae are latent feeders, which cause great damage and economic losses to agriculture production and trade. This study aimed to provide a scientific reference for researching and developing the feasible countermeasures against these two pests. Based on the distribution data of B. minax and B. dorsalis in China, obtained from the Chinese herbaria, investigation and literature. Four niche models (Garp, Bioclim, Domain, and Maxent) were used to analyze the key environmental factors affecting the distribution of both pests and to build prediction models of the potential distribution in Sichuan Basin. Combined with two statistical standards, area under the receiver operating characteristic curve (AUC) and Kappa, the validity of prediction models were analyzed and compared. The results show that: the average AUC values of the four models are all above 0.90, and the average Kappa values are all above 0.75, indicating that the four models are suitable for predicting the potential distribution area of B. minax and B. dorsalis. The annual range of temperature, the mean temperature in the driest quarter, the mean temperature in the warmest quarter, the annual precipitation, and the precipitation in driest month are the key environmental factors affecting the distribution of B. minax, while the mean diurnal temperature range, the mean temperature in the driest quarter, the seasonal temperature variations and the precipitation in driest month affect the potential distribution of B. dorsalis. The suitable areas for B. minax are mainly concentrated in the eastern of Sichuan Basin, while the suitable areas for B. dorsalis are concentrated in the southeastern. Except for the Bioclim model, the highly-suitable area for both pests predicted by the other three models are all greater than 15.94 × 104 km2 and the moderately-suitable areas are greater than 13.57 × 104 km2. In conclusion, the suitable areas for both pests in Sichuan Basin are quite wide. Therefore, the relevant authorities should be given strengthened monitoring of both pests, especially in areas with high incursion rates.

Conservation genetics and potential geographic distribution modeling of Corybas taliensis, a small 'sky Island' orchid species in China

BACKGROUND

Corybas taliensis is an endemic species of sky islands in China. Its habitat is fragile and unstable, and it is likely that the species is threatened. However, it is difficult to determine the conservation priority or unit without knowing the genetic background and the overall distribution of this species. In this study, we used double digest restriction-site associated DNA-sequencing (ddRAD-seq) to investigate the conservation genomics of C. taliensis. At the same time, we modeled the extent of suitable habitat for C. taliensis in present and future (2030 and 2090) habitat using the maximum-entropy (MaxEnt) model.

RESULTS

The results suggested that the related C. fanjingshanensis belongs to C. taliensis and should not be considered a separate species. All the sampling locations were divided into three genetic groups: the Sichuan & Guizhou population (SG population), the Hengduan Mountains population (HD population) and Himalayan population (HM population), and we found that there was complex gene flow between the sampling locations of HD population. MT was distinct genetically from the other sampling locations due to the unique environment in Motuo. The genetic diversity (π, He) of C. taliensis was relatively high, but its contemporary effective population size (Ne) was small. C. taliensis might be currently affected by inbreeding depression, although its large population density may be able to reduce the effect of this. The predicted areas of suitable habitat currently found in higher mountains will not change significantly in the future, and these suitable habitats are predicted to spread to other higher mountains under future climate change. However, suitable habitat in relatively low altitude areas may disappear in the future. This suggests that C. taliensis will be caught in a 'summit trap' in low altitude areas, however, in contrast, the high altitude of the Himalaya and the Hengduan Mountains are predicted to act as 'biological refuges' for C. taliensis in the future.

CONCLUSIONS

These results not only provide a new understanding of the genetic background and potential resource distribution of C. taliensis, but also lay the foundation for its conservation and management.

Future habitat changes of Bactrocera minax Enderlein along the Yangtze River Basin using the optimal MaxEnt model

Background

Bactrocera minax (Enderlein, 1920) (Diptera: Tephritidae) is a destructive citrus pest. It is mainly distributed throughout Shaanxi, Sichuan, Chongqing, Guizhou, Yunnan, Hubei, Hunan, and Guangxi in China and is considered to be a second-class pest that is prohibited from entering that country. Climate change, new farming techniques, and increased international trade has caused the habitable area of this pest to gradually expand. Understanding the suitable habitats of B. minax under future climate scenarios may be crucial to reveal the expansion pattern of the insect and develop corresponding prevention strategies in China.

Methods

Using on the current 199 distribution points and 11 environmental variables for B. minax, we chose the optimal MaxEnt model to screen the dominant factors that affect the distribution of B. minax and to predict the potential future distribution of B. minax in China under two shared socio-economic pathways (SSP1-2.6, SSP5-8.5).

Results

The current habitat of B. minax is located at 24.1-34.6°N and 101.1-122.9°E, which encompasses the provinces of Guizhou, Sichuan, Hubei, Hunan, Chongqing, and Yunnan (21.64 × 104 km2). Under future climate scenarios, the potential suitable habitat for B. minax may expand significantly toward the lower-middle reaches of the Yangtze River. The land coverage of highly suitable habitats may increase from 21.64 × 104 km2 to 26.35 × 104 × 104 km2 (2050s, SSP5-8.5) ~ 33.51 × 104 km2 (2090s, SSP5-8.5). This expansion area accounts for 29% (2050s, SSP1-2.6) to 34.83% (2090s, SSP1-2.6) of the current habitat. The center of the suitable habitat was predicted to expand towards the northeast, and the scenario with a stronger radiative force corresponded to a more marked movement of the center toward higher latitudes. A jackknife test showed that the dominant variables affecting the distribution of B. minax were the mean temperature of the driest quarter (bio9), the annual precipitation (bio12), the mean diurnal range (bio2), the temperature annual range (bio7), and the altitude (alt).

Discussion

Currently, it is possible for B. minax to expand its damaging presence. Regions with appropriate climate conditions and distribution of host plants may become potential habitats for the insects, and local authorities should strengthen their detection and prevention strategies. Climate changes in the future may promote the survival and expansion of B. minax species in China, which is represented by the significant increase of suitable habitats toward regions of high altitudes and latitudes across all directions but with some shrinkage in the east and west sides.

Buchanania cochinchinensis (Lour.) M.R. Almedia habitat exhibited robust adaptability to diverse socioeconomic scenarios in eastern India

One of the greatest challenges to ecosystems is the rapidity of climate change, and their ability to adjust swiftly will be constrained. Climate change will disrupt the ecological balances, causing species to track suitable habitats for survival. Consequently, understanding the species' response to climate change is crucial for its conservation and management, and for enhancing biodiversity through effective management. This research intends to examine the response of the vulnerable Buchanania cochinchinensis species to climate change. We modeled the potential suitable habitats of B. cochinchinensis for the present and future climatic scenario proxies based on the Shared Socioeconomic Pathways (SSP), i.e. SSP126, 245, 370 and 585. Maxent was used to simulate the potential habitats of B. cochinchinensis. The study found that ~28,313 km2 (~10.7% of the study area) was a potentially suitable habitat of B. cochinchinensis for the current scenario. The majority of the suitable habitat area ~25,169 km2 occurred in the central and southern parts of the study area. The future projection shows that the suitable habitat to largely increase in the range of 10.5-20% across all the SSPs, with a maximum gain of ~20% for SSP 126. The mean temperature of the wettest quarter (Bio_08) was the most influential contributing variable in limiting the distribution of B. cochinchinensis. The majority of the suitable habitat area occurred in the vegetation landscape. The study shows a southward shifting of B. cochinchinensis habitat by 2050. The phytosociological analysis determined B. cochinchinensis as Shorea robusta's primary associate. Our research provides significant insight into the prospective distribution scenario of B. cochinchinensis habitat and its response to diverse socioeconomic scenarios, and offers a solid foundation for management of this extremely important species.

Environmental predictors may change at fine scale habitat suitability modelling: implications for conservation of Kashmir musk deer in three protected areas of Uttarakhand, India

The Kashmir musk deer (Moschus cupreus, hereafter KMD) is one of the top conservation priority species which is facing population decline due to poaching, habitat loss, and climate change. Therefore, the long-term survival and viability of KMD populations in their natural habitat require conservation and management of suitable habitats. Hence, the present study attempted to assess the suitable habitat of KMD in three protected areas (PAs) of the Western Himalayan region of Uttarakhand using the Maxent modelling algorithm. Our results suggest that Kedarnath wildlife sanctuary (KWLS) possesses the maximum highly suitable habitats (22.55%) of KMD, followed by Govind Pashu Vihar National Park & Sanctuary (GPVNP&S; 8.33%) and Gangotri National Park (GNP; 5%). Among the environmental variables, altitude was the major contributing factor governing the distribution of KMD in KWLS. In contrast, human footprint in GPVNP&S and precipitation in GNP were the major contributing factors governing the distribution of KMD in these respective PAs. The response curve indicated that habitats with less disturbance falling in the altitudinal zone of 2000-4000 m were the most suitable habitat range for the distribution of KMD in all three PAs. However, in the case of GNP suitable habitat of KMD increases with an increase in the value of variables bio_13 (precipitation of wettest month). Further, based on our results, we believe that the predictors of suitable habitat change are site specific and cannot be generalized in the entire distribution range of the species. Therefore, the present study will be helpful in making proper habitat management actions at fine scale for the conservation of KMD.

[Prediction of potential suitable habitats of Haemphysalis concinna in Heilongjiang Province based on the maximum entropy model]

OBJECTIVE

To predict the potential suitable habitat of Haemaphysalis concinna in Heilongjiang Province under different climatic scenarios.

METHODS

The geographic locations of ticks in Heilongjiang Province from 1980 to 2022 were captured from literature review and field ticks monitoring data from Harbin Center for Disease Control and Prevention in Heilongjiang Province, and the tick distribution sites with spatial correlations were removed using the software ArcGIS 10.2. The environment data under historical climatic scenarios from 1970 to 2000 and the climatic shared socioeconomic pathways (SSP) 126 scenario model from 2021 to 2040 and from 2041 to 2060 were downloaded from the WorldClim website, and the elevation (1 km, 2010), population (1 km grid population dataset of China, 2010) and annual vegetation index (1 km, 2010) data were downloaded from the Resource and Environmental Science and Data Center, Institute of Geographical Sciences and Natural Resources, Chinese Academy of Sciences. The contribution of environmental factors to H. concinna distribution was evaluated and environmental variables were screened using the software MaxEnt 3.4.1 and R package 4.1.0, and the areas of suitable habitats of H. concinna and changes in center of gravity were analyzed using the maximum entropy model in Heilongjiang Province under different climatic scenarios. In addition, the accuracy of the maximum entropy model for prediction of H. concinna distribution was assessed using the area under curve (AUC) of the receiver operating characteristic curve.

RESULTS

A total of 79 H. concinna distribution sites and 24 environmental variables were collected, and 70 H. concinna distribution sites and 9 environmental factors that contributed to distribution of the potential suitable habitats of H. concinna in Heilongjiang Province were screened. The three most significant contributing factors included precipitation seasonality, annual precipitation, and mean temperature of the driest quarter, with cumulative contributions of 60.7%. The total area of suitable habitats of H. concinna was 29.05 × 10⁴ km² in Heilongjiang Province under historical climatic scenarios, with the center of gravity of suitable habitats located at (47.31° N, 129.16° E), while the total area of suitable habitats of H. concinna reduced by 0.97 × 10⁴ km² in Heilongjiang Province under the climatic SSP126 scenario from 2041 to 2060, with the center of gravity shifting to (47.70° N, 129.28° E).

CONCLUSIONS

The distribution of suitable habitats of H. concinna strongly correlates with temperature and humidity in Heilongjiang Province. The total area of potential suitable habitats of H. concinna may appear a tendency towards a decline with climatic changes in Heilongjiang Province, and high-, medium- and low-suitable habitats may shift.

Prediction of the potential suitable habitat of Echinococcus granulosus, the pathogen of echinococcosis, in the Tibetan Plateau under future climate scenarios

Echinococcosis is a zoonotic parasitic infectious disease caused by human or domestic animals infected with Echinococcus granulosus. China is the country with the heaviest disease burden caused by Echinococcosis in the world. Therefore, it is feasible to evaluate the prevalence and distribution of echinococcosis using relevant ecological methods, combined with environmental factors and human activities. In this study, MaxEnt was used to predict the distribution range of E. granulosus in China under current and future climate scenarios and explain the impact of environmental variables on its distribution. The results showed that elevation (El), annual mean temperature (bio1), human footprint (Hf), annual precipitation (bio12), mean temperature of warmest quarter (bio10), and mean temperature of wettest quarter (bio8) were identified as the dominant environmental variables. In Tibet, the most suitable habitats (25.9 × 10⁴ km²) of E. granulosus were distributed in Nyingchi and Qamdo in the east, Shigatse and Shannan in the south, and Ali in the west. In Sichuan, the most suitable habitat (18.83 × 10⁴ km²) was located in Aba, Ganzi, and Liangshan. In Qinghai, the most suitable habitat (13.05 × 10⁴ km²) mainly included Yushu in the southwest; Guoluo in the southeast; Haidong, Huangnan, Xining, and Hainan in the east; and Haixi in the west. In Gansu, the most suitable habitat (7.36 × 10⁴ km²) was located in Gannan and Linxia in the southwest and Wuwei and Dingxi in the middle. In Yunnan, the most suitable habitat (1.53 × 10⁴ km²) was distributed in Diqing in the northwest. Under future climate scenarios, the area of the most suitable habitat of E. granulosus showed an obvious expansion trend, with an increase of 44.64-70.76%. Trajectory trend of centroids showed that the most suitable habitat would move to the west in the future, and the increased areas were mainly located in the west of the current most suitable habitat. AUC values of the training data and test data were 0.936 ± 0.001 ~ 0.97 ± 0.006 and 0.912 ± 0.006 ~ 0.956 ± 0.015, respectively. The result can provide a theoretical basis for the prevention, monitoring, and early warning of echinococcosis in China.

Assessing the current genetic structure of 21 remnant populations and predicting the impacts of climate change on the geographic distribution of Phoebe sheareri in southern China

Phoebe sheareri is a valuable tree species known as "Golden Nanmu" and is one of the most important protected tree species in China. However, natural populations are decreasing because of climate change and anthropogenic factors. To evaluate the genetic diversity and structure of remnant populations and the impacts of climate change on the distribution of potential suitable habitats, we conducted a field investigation and sampled 21 P. sheareri natural populations to evaluate their genetic diversity and structure using simple sequence repeat (SSR) molecular markers. Then, we predicted the distribution of suitable P. sheareri habitats across China under future scenarios (RCP 2.6 and RCP 8.5) and periods (2050 and 2070) using multivariate modeling methods-the MaxEnt model. The results showed a medium level of genetic diversity and low inbreeding in the 21 P. sheareri natural populations, and genetic differentiation among populations was significant, with 21.2 % genetic variation among populations. The remnant populations of P. sheareri were grouped into four genetic clusters based on genetic structure; five environmental variables involving four temperature variables and precipitation seasonality (Bio12) might determine the distribution of P. sheareri populations. In the future, the suitable habitats of P. sheareri are manifested as northward migration, and the highly suitable habitats are expected to increase. Our results highlight the importance of conservation units in situ, giving priority to populations with higher genetic diversity (e.g., TMS, FJS, and THY populations); sampling strategies for ex situ conservation, breeding and reforestation should consider climate change, especially Bio1 (annual mean temperature) and Bio12 (annual precipitation). Overall, this study may provide useful genetic information for strategies for the protection, management, and utilization of P. sheareri.

Use of Habitat Suitability Model as a Tool to Highlight Best Conservation Area for the Red-bellied Monkey (Cercopithecus erythrogaster erythrogaster) in Southern-Benin, West Africa

Wildlife habitats are increasingly degraded as a result of anthropogenic pressures. The IUCN recently updated the red list category of the red-bellied monkey (Cercopithecus erythrogaster erythrogaster) from Endangered to Critically Endangered due to its population decrease, habitats degradation and various threats to its conservation. It is therefore important to identify areas of great importance for the sustainable conservation of the subspecies. The Species Distribution Model (SDM) is a method increasingly used by conservationists to help find these areas and thus limit areas of intervention. In this study, maximum entropy model was used to identify suitable habitats for the red-bellied monkey in landscape of southern-Benin from occurrence data and selected predictor variables according to ecological habitat requirements of the subspecies. The suitable habitat model for the red-bellied monkey has a good predictive power (AUC = 0.97). The variables that contributed most to the final model, as indicated by the permutation importance, were: Distance to Water (47.7%), Land Cover Class (23.1%), Brightness (17.0%), Wetness (4.7%), Human Population Size (2.8%) and Elevation (2.2%). Thus, using Maximum Training sensitivity and Specificity threshold, 3.62% of the landscape was classified as suitable and 96.38% was classified as unsuitable for the red-bellied monkey. The largest area of suitable habitat is found in protected areas (57.46%), mainly in the Lama Forest Reserve central core (49.5%). The landscape is fragmented and 91.49% of suitable habitats are between 0 and 0.01 km² in size. The mean size of suitable habitats in the landscape is 0.017 ± 0.545 km². Nevertheless, there is no significant difference between the mean size of suitable habitats in protected areas and those in the unprotected area (P = 0.061, Mann-Whitney U tests). The Average Nearest Neighbor Distance of suitable habitats in the landscape is low (0.139 km) and the Average Nearest Neighbor Ratio (R) is less than 1 (R = 0.408, p < 0.001). Those features indicate a clustered pattern of suitable habitats for the red-bellied monkey in the landscape. This makes it possible to foresee the establishment of connections between the isolated suitable habitats and thus allow for the long-term conservation of the species populations.

Predicting the potential distribution of the cattle fever tick Rhipicephalus annulatus (Acari: Ixodidae) using ecological niche modeling

Rhipicephalus annulatus is a tick species of veterinary importance due to its potential to transmit babesiosis to cattle. This species has a Holarctic distribution with some Afrotropical records and is one-host species of veterinary importance. This study was carried out from September 2021 to February 2022 at 6 Egyptian collection sites, and a total of 1150 cattle were scanned randomly to collect ticks. A total of 1095 tick specimens were collected and identified as R. annulatus using taxonomic keys. Males were found on all parts of the cattle except the head and around the eyes, but females were found on all parts; in addition, the highest number of specimens was gathered from the udder, (neck and chest), and belly. Maximum entropy (MaxEnt) modeling was used to predict the potential global distribution of R. annulatus. The MaxEnt model performed better than random with an average test area under the curve (AUC) value of 0.96, and model predictions were significantly better than random and gave (AUC) ratios above the null expectations in the partial receiver operating characteristic (pROC) analyses (P < 0.001). Based on correlation analyses, a set of 9 variables was selected for species from 15 bioclimatic and 5 normalized difference vegetation index (NDVI) variables. The study showed that the current distribution of R. annulatus is estimated to occur across Asia, Africa, Europe, South America, and North America. Annual mean temperature (Bio1) and median NDVI had the highest effect on the distribution of this species. The environmentally suitable habitat for R. annulatus sharply increased with increasing annual mean temperature (Bio1). These results can be used for making effective control planning decisions in areas suitable to this vector of many diseases worldwide.

Prediction of the dynamic distribution for Eucheuma denticulatum (Rhodophyta, Solieriaceae) under climate change in the Indo-Pacific Ocean

Eucheuma is one of the most important commercial red seaweeds in Southeast Asia, and plays an important role in the global seaweed aquaculture. It is expected to exhibit great responses to ocean warming. Here, we used maximum entropy species distribution models (SDMs) to estimate the suitable habitat of Eucheuma denticulatum under present conditions, and to predict the future range dynamics under the four representative concentration pathway (RCP) scenarios. The best marine environmental factors for E. denticulatum distribution modeling were distance to shore, sea surface temperature and currents velocity. Our results showed that E. denticulatum' distributions would contract in the Central Indo-Pacific Ocean, especially the regions of the Sunda Shelf, while expanding poleward along the south coast of Australia in 2100. Our study provided important knowledge for the prediction of the tropical seaweed distribution, conservation and sustainable developments of E. denticulatum in the future.

Potential distribution of Blumea balsamifera in China using MaxEnt and the ex situ conservation based on its effective components and fresh leaf yield

Blumea balsamifera is a famous Chinese Minority Medicine, which has a long history in Miao, Li, Zhuang, and other minority areas. In recent years, due to the influence of natural and human factors, the distribution area of B. balsamifera resources has a decreasing trend. Therefore, it is very important to analyze the suitability of B. balsamifera in China. Following three climate change scenarios (SSP1-2.6, SSP2-4.5, and SSP5-8.5) under 2050s and 2070s, geographic information technology (GIS) and maximum entropy model (MaxEnt) were used to simulate the ecological suitability of B. balsamifera. The contents of L-borneol and total flavonoids of B. balsamifera in different populations were determined by gas chromatography (GC) and ultraviolet spectrophotometry (UV). The results showed that the key environmental variables affecting the distribution of B. balsamifera were mean temperature of coldest quarter (6.18-26.57 ℃), precipitation of driest quarter (22.46-169.7 mm), annual precipitation (518.36-1845.29 mm), and temperature seasonality (291.31-878.87). Under current climate situation, the highly suitable habitat was mainly located western Guangxi, southern Yunnan, most of Hainan, southwestern Guizhou, southwestern Guangdong, southeastern Fujian, and western Taiwan, with a total area of 24.1 × 10⁴ km². The areas of the moderately and poorly suitable habitats were 27.57 × 10⁴ km² and 42.43 × 10⁴ km², respectively. Under the future climate change scenarios, the areas of the highly, moderately, and poorly suitable habitats of B. balsamifera showed a significant increasing trend, the geometric center of the total suitable habitats of B. balsamifera would move to the northeast. In recent years, the planting area of B. balsamifera has been reduced on a large scale in Guizhou, and its ex situ protection is imperative. By comparison, the content of L-borneol, total flavonoids and fresh leaf yield had no significant difference between Guizhou and Hainan (P > 0.05), which indicated that Hainan is one of the best choice for ex situ protection of B. balsamifera.

Mountain frog species losing out to climate change around the Sichuan Basin

Amphibians are particularly vulnerable to climate changes that are expected to cause habitat fragmentation and loss and, ultimately, local extirpations. However, little is known about how the interaction between climate change and fragmentation may impede the ability of amphibians to adapt to climate change. Here, we used the iconic mountain frog Quasipaa boulengeri as an indicator species to extrapolate climate-driven shifts in its habitat availability and connectivity in central and southern China according to the minimum and maximum representative concentration pathways. The models projected an average habitat loss of 36%-71% and the in situ and ex situ climate-change refugia to be 29%-64% and 5%-18% of the present-day suitable habitats, respectively. An increase in habitat fragmentation was reflected in a 51% decrease in core patch size, a 9% increase in the mean least-cost path (LCP) length, and a 19% increase in the cost-weighted distance. These climate-driven shifts varied spatially around the Sichuan Basin, with those in the southeast of the Basin being the most pronounced habitat and connectivity losses and those along the Basin being relatively optimistic. The effectiveness of refugia may only be maintained through a narrow passageway along the southern Sichuan Basin because of the presence of LCPs over time. Our results emphasize the need to understand how climate change and connectivity will jointly affect the distribution of mountain amphibians and to accordingly adopt conservation strategies. Further, our findings highlight the importance of identifying and preserving climate-change refugia and habitat connectivity for species persistence and conservation planning.

[Potential suitable habitats of Haemaphysalis longicornis in China under different climatic patterns]

OBJECTIVE

To evaluate the impact of environmental and climatic factors on the distribution of suitable habitats of Haemaphysalis longicornis, and to predict the potential distribution of H. longicornis under different climate patterns in China.

METHODS

Data pertaining to the distribution of H. longicornis were retrieved from public literatures. The effects of 19 climatic factors (annual mean temperature, annual mean temperature difference between day and night, isothermality, standard deviation of seasonal variation of temperature, maximum temperature of the warmest month, minimum temperature of the coldest month, temperature annual range, mean temperature of the wettest season, mean temperature of the driest season, mean temperature of the warmest season, mean temperature of the coldest season, annual mean precipitation, precipitation of the wettest month, precipitation of the driest month, coefficient of variance of precipitation, precipitation of the wettest season, precipitation of the driest season, precipitation of the warmest season and precipitation of the coldest season) and 4 environmental factors (elevation, slope, slope aspect and vegetation coverage) on the potential distribution of H. longicornis were assessed using the maximum entropy (MaxEnt) model based on the H. longicornis distribution data and climatic and environmental data, and the potential distribution of H. longicornis was predicted under the RCP 2.6 and 8.5 emissions scenarios.

RESULTS

Among the environmental and climatic factors affecting the geographical distribution of H. longicornis in China, the factors contributing more than 10% to the distribution of H. longicornis mainly included the precipitation of the driest month (26.0%), annual mean temperature (11.2%), annual mean precipitation (10.0%) and elevation (24.2%). Under the current climate pattern, the high-, medium- and low-suitable habitats of H. longicornis are 1 231 900, 1 696 200 km² and 1 854 400 km² in China, respectively. The distribution of H. longicornis increased by 336 100 km² and 367 300 km² in 2050 and 2070 under the RCP 2.6 emissions scenario, and increased by 381 000 km² and 358 000 km² in 2050 and 2070 under the RCP 8.5 emissions scenario in China, respectively.

CONCLUSIONS

Climatic and environmental factors, such as precipitation, temperature and elevation, greatly affect the distribution of H. longicornis in China, and the suitable habitats of H. longicornis may expand in China under different climate patterns in future.

[Distribution and suitable habitats of ticks in the Yangtze River Delta urban agglomeration]

OBJECTIVE

To investigate the current distribution of ticks and predict the suitable habitats of ticks in the Yangtze River Delta urban agglomeration in 2017, so as to provide insights into tick control and management of tick-borne diseases in these areas.

METHODS

All publications pertaining to tick and pathogen distribution in the Yangtze River Delta urban agglomeration were retrieved, and the geographical location of tick distribution was extracted. The effects of 19 climatic factors on the distribution of ticks were examined using the jackknife method, including the mean temperature of the wettest quarter, precipitation of the coldest quarter, mean temperature of the driest quarter, maximum temperature of the warmest month, precipitation of the driest month, minimal temperature of the coldest month, annual precipitation, mean daily temperature range, precipitation seasonality, annual temperature range, temperature seasonality, annual mean temperature, mean temperature of the warmest quarter, precipitation of the wettest quarter, isothermality, mean temperature of the coldest quarter, precipitation of the wettest month, precipitation of the driest quarter and precipitation of the warmest quarter. The distribution of ticks was analyzed in 2020 using the maximum entropy (MaxEnt) model, and the potential suitable habitats of ticks were predicted in 2070 using the MaxEnt model based on climatic data.

RESULTS

A total of 380 Chinese and English literatures were retrieved, and 148 tick distribution sites were extracted, with 135 sites included in the subsequent analysis. There were 7 genera (Haemaphysalis, Rhipicephalus, Ixodes, Dermacentor, Boophilus, Hyalomma and Amblyomma) and 27 species of ticks detected in the Yangtze River Delta urban agglomeration. The climatic factors affecting the distribution of ticks in the Yangtze River Delta urban agglomeration mainly included the mean temperature of the wettest quarter and the precipitation of the coldest quarter, with 26.1% and 23.6% contributions to tick distributions. The high-, medium- and low-suitable habitats of ticks were 20 337.08, 40 017.38 km² and 74 931.43 km² in the Yangtze River Delta urban agglomeration in 2020, respectively. The climate changes led to south expansion of the suitable habitats of ticks in the Yangtze River Delta urban agglomeration in 2070, and the total areas of suitable habitats of ticks was predicted to increase by 18 100 km². In addition, the high-, medium- and low-suitable habitats of ticks were predicted to increase to 24 317.84, 45 283.02 km² and 83 766.38 km² in the Yangtze River Delta urban agglomeration in 2070, respectively.

CONCLUSIONS

Multiple tick species are widespread in the Yangtze River Delta urban agglomeration, and the future climate changes may lead to expansion of tick distribution in these areas.

[Effects of climate changes on the distribution of Rhipicephalus microplus in China]

OBJECTIVE

To identify the environmental factors affecting the geographical distribution of Rhipicephalus microplus in China, and to examine the impact of climate changes on the distribution of R. microplus in China.

METHODS

The national and international publications pertaining to the geographical distribution of R. microplus in China were retrieved, and the geographical location was extracted. The suitable habitats of R. microplus and the dominant environmental factors affecting the distribution of suitable habitats of R. microplus were predicted in China based on the geographical data and environmental variables using the ArcGIS 10.7 software and the maximum entropy model.

RESULTS

Among the main climatic factors affecting the geographical distribution of R. microplus in China, the factors contributing more than 10% to the suitable habitats of R. microplus mainly include the annual mean precipitation (38.2%), the average temperature of the coldest quarter (28.4%) and the precipitation of the driest month (14.2%). The current suitable habitats of R. microplus were mainly found in southern China, and the high-, medium- and low-suitable areas accounted for 8.6%, 13.1% and 10.5% of the total land area of China, respectively. The suitable habitats of R. microplus were predicted to increase by 399 800 km² in China using the maximum entropy model under the RCP 4.5 emissions scenario in 2070, and the emerging suitable habitats were mainly distributed in Gansu Province, Ningxia Hui Autonomous Region, Qinghai Province, Hebei Province, Shaanxi Province, Liaoning Province, Inner Mongolia Autonomous Region, Shandong Province, Sichuan Province and Tibeten Autonomous Region. In addition, the suitable habitats of R. microplus were predicted to show an overall expansion towards northward from present to 2070.

CONCLUSIONS

Climate changes affect the distribution of suitable habitats of R. microplus in China, and annual mean precipitation may be a key factor affecting the distribution of suitable habitats of R. microplus.

[Effects of environmental factors on the distribution of suitable habitats of Ixodes ovatus in China]

OBJECTIVE

To identify the environmental factors affecting the distribution of suitable habitats of Ixodes ovatus, and to examine the effects of environmental changes on the distribution of suitable habitats of I. ovatus.

METHODS

Data pertaining to the distribution of I. ovatus in China were captured by literature review. The distribution of suitable habitats of I. ovatus in China was simulated using the maximum entropy model with the environmental variable data and the I. ovatus distribution data. In addition, the potential distribution of suitable habitats of I. ovatus was predicted based on the 2050 and 2070 environmental data.

RESULTS

The current suitable habitats of I. ovatus cover 3.11 million km², accounting for 32.28% of the total land area of China, and they are mainly concentrated in southwestern and northwestern China. Among the screened 16 environmental factors, the standard deviation of seasonal variation of temperature, average annual precipitation and altitude were predominant environmental factors affecting the distribution of suitable habitats of I. ovatus, and these three variables contributed 76.5% to the distribution of suitable habitats of I. ovatus in China. The suitable habitats of I. ovatus were predicted to showing a tendency towards expansion to northwestern and northeastern China in 2050 and 2070, and the proportion of highly suitable habitats of I. ovatus was predicted to increase.

CONCLUSIONS

Moderate climate, adequate precipitation and high altitude are favorable for the survival of I. ovatus. Future climate changes may cause expansion of suitable habitats of I. ovatus in China.

[Prediction of suitable habitats of Ixodes persulcatus in China]

OBJECTIVE

To evaluate the effects of environmental factors the distribution of Ixodes persulcatus, and to predict the future suitable habitats of I. persulcatus in China.

METHODS

The known distribution sites of I. persulcatus in China were captured from national and international published literatures. The effects of 14 environmental factors on the distribution of I. persulcatus were examined using the Jackknife test, including mean annual temperature, mean monthly temperature range, isothermality, temperature seasonality, maximum temperature of the warmest month, minimum temperature of the coldest month, temperature annual range, mean temperature of the wettest quarter, mean temperature of the driest quarter, mean temperature of the wet-test quarter, mean temperature of the coldest quarter, annual mean precipitation, precipitation of the wettest month, precipitation of the driest month, precipitation seasonality, precipitation of the wettest quarter, precipitation of the driest quarter, precipitation of the warmest quarter, precipitation of the coldest quarter, elevation, slope, aspect and vegetation. The suitable habitats of I. persulcatus were predicted in China using the maximum entropy model and ArcGIS 10.7 software with the environmental factors.

RESULTS

Currently, the highly suitable habitats of I. persulcatus covered an area of 886 600 km² in China, which were predominantly located in northeastern China. The environmental factors that contributed more than 10% to the distribution of the suitable habitats of I. persulcatus in China included annual temperature variation range (39.1%), the coldest quarterly precipitation (23.2%), and the annual mean precipitation (11.9%). Based on the maximum entropy model, the suitable habitats of I. persulcatus were predicted to show a shrinking tendency towards northeastern China in 2070.

CONCLUSIONS

The suitable habitat of I. persulcatus strongly correlates with temperature and precipitation, and climate and environmental changes may lead to shrinking of the future suitable habitat of I. persulcatus in China.

Combining the responses of habitat suitability and connectivity to climate change for an East Asian endemic frog

Background

Understanding the impacts of past and contemporary climate change on biodiversity is critical for effective conservation. Amphibians have weak dispersal abilities, putting them at risk of habitat fragmentation and loss. Both climate change and anthropogenic disturbances exacerbate these risks, increasing the likelihood of additional amphibian extinctions in the near future. The giant spiny frog (Quasipaa spinosa), an endemic species to East Asia, has faced a dramatic population decline over the last few decades. Using the giant spiny frog as an indicator to explore how past and future climate changes affect landscape connectivity, we characterized the shifts in the suitable habitat and habitat connectivity of the frog.

Results

We found a clear northward shift and a reduction in the extent of suitable habitat during the Last Glacial Maximum for giant spiny frogs; since that time, there has been an expansion of the available habitat. Our modelling showed that “overwarm” climatic conditions would most likely cause a decrease in the available habitat and an increase in the magnitude of population fragmentation in the future. We found that the habitat connectivity of the studied frogs will decrease by 50–75% under future climate change. Our results strengthen the notion that the mountains in southern China and the Sino-Vietnamese transboundary regions can act as critical refugia and priority areas of conservation planning going forward.

Conclusions

Given that amphibians are highly sensitive to environmental changes, our findings highlight that the responses of habitat suitability and connectivity to climate change can be critical considerations in future conservation measures for species with weak dispersal abilities and should not be neglected, as they all too often are.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12983-021-00398-w.

Climate change may threaten habitat suitability of threatened plant species within Chinese nature reserves

Climate change has the potential to alter the distributions of threatened plant species, and may therefore diminish the capacity of nature reserves to protect threatened plant species. Chinese nature reserves contain a rich diversity of plant species that are at risk of becoming more threatened by climate change. Hence, it is urgent to identify the extent to which future climate change may compromise the suitability of threatened plant species habitats within Chinese nature reserves. Here, we modelled the climate suitability of 82 threatened plant species within 168 nature reserves across climate change scenarios. We used Maxent modelling based on species occurrence localities and evaluated climate change impacts using the magnitude of change in climate suitability and the degree of overlap between current and future climatically suitable habitats. There was a significant relationship between overlap with current and future climate suitability of all threatened plant species habitats and the magnitude of changes in climate suitability. Our projections estimate that the climate suitability of more than 60 threatened plant species will decrease and that climate change threatens the habitat suitability of plant species in more than 130 nature reserves under the low, medium, and high greenhouse gas concentration scenarios by both 2050s and 2080s. Furthermore, future climate change may substantially threaten tree plant species through changes in annual mean temperature. These results indicate that climate change may threaten plant species that occur within Chinese nature reserves. Therefore, we suggest that climate change projections should be integrated into the conservation and management of threatened plant species within nature reserves.

Estimating relative risk of within-lake aquatic plant invasion using combined measures of recreational boater movement and habitat suitability

Effective monitoring, prevention and impact mitigation of nonindigenous aquatic species relies upon the ability to predict dispersal pathways and receiving habitats with the greatest risk of establishment. To examine mechanisms affecting species establishment within a large lake, we combined observations of recreational boater movements with empirical measurements of habitat suitability represented by nearshore wave energy to assess the relative risk of Eurasian watermilfoil (Myriophyllum spicatum) establishment. The model was evaluated using information from a 17 year (1995-2012) sequence of M. spicatum presence and absence monitoring. M. spicatum presence was not specifically correlated with recreational boater movements; however its establishment appears to be limited by wave action in Lake Tahoe. Of the sites in the "High" establishment risk category (n = 37), 54% had current or historical infestations, which included 8 of the 10 sites with the highest relative risk. Of the 11 sites in the "Medium" establishment risk category, 5 had current or historical M. spicatum populations. Most (76%) of the sites in the "Low" establishment risk category were observed in locations with higher wave action. Four sites that received zero boater visits from infested locations were occupied by M. spicatum. This suggests that the boater survey either represents incomplete coverage of boater movement, or other processes, such as the movement of propagules by surface currents or introductions from external sources are important to the establishment of this species. This study showed the combination of habitat specific and dispersal data in a relative risk framework can potentially reduce uncertainty in estimates of invasion risk.