In urban landscape, amphibians face many challenges in order to sustain their populations, such as road mortality and infection of pathogenic Batrachochytrium dendrobatidis (Bd). Bd infection has been reported to caus...In urban landscape, amphibians face many challenges in order to sustain their populations, such as road mortality and infection of pathogenic Batrachochytrium dendrobatidis (Bd). Bd infection has been reported to cause significant mortality;however, its current distribution in the state of New Jersey remains unknown. In spring, amphibians emerge from their wintering group and migrate to nearby breeding ponds or vernal pools. Their migration pathway is often intercepted by the dense network of human transportation which leads to extirpation. This study aims to investigate potential mortality caused by human transportation and the infected rate of Bd fungus on the amphibian populations at a suburban area in central New Jersey. Twenty-four pitfall traps were installed to collect amphibians. A total of 687 organisms representing 7 amphibian species were recorded during the 73-day study period. Four of the 7 species were selected to test for Bd infection;73.6% of the amphibian skin swabs showed positive results of infection. However, Bd was not detected in water and soil samples collected around the study areas. The results of this study suggested that road mortality and pathogenic Bd might have tremendously impacted the urban amphibian populations and might have been the major causes of the current trend of amphibian population decline, particularly in the urban area.展开更多
For the last decade, chytridiomycosis was considered to be caused by a single species of fungus, Batrachochytrium dendrobatidis （Bd）, but a second chytrid species, Batrachochytrium salamandrivorans （Bs）, was recen...For the last decade, chytridiomycosis was considered to be caused by a single species of fungus, Batrachochytrium dendrobatidis （Bd）, but a second chytrid species, Batrachochytrium salamandrivorans （Bs）, was recently isolated from an in- fected Salamandra salamandra in the Netherlands. To date, Bs has only been found in the Netherlands. To assess whether Bs is present in China, we analyzed a total of 665 samples, including 425 wild samples, 41 preserved specimens, and 199 captive sam- pies, from 30 different species, including both urodeles and anurans. Our sample sites covered 15 provinces in China. All of the samples tested negative for Bs, resulting in a 95% confidence limit for a prevalence of 0.6%. The absence of Bs observed in this large-scale survey in China has significant implications for amphibian conservation and for border trade management strategies intended to control amphibian diseases. We strongly recommend the continued close monitoring of Bs to verify the status of this potentially devastating amphibian fungus in China .展开更多
Chytridiomycosis,an infectious skin disease caused by the chytrid fungi,Batrachochytrium dendrobatidis and B.salamandrivorans,poses a significant threat to amphibian biodiversity worldwide.Antifungal bacteria found on...Chytridiomycosis,an infectious skin disease caused by the chytrid fungi,Batrachochytrium dendrobatidis and B.salamandrivorans,poses a significant threat to amphibian biodiversity worldwide.Antifungal bacteria found on the skin of chytrid-resistant amphibians could potentially provide defense against chytridiomycosis and lower mortality rates among resistant individuals.The Hong Kong newt(Paramesotriton hongkongensis)is native to East Asia,a region suspected to be the origin of chytrids,and has exhibited asymptomatic infection,suggesting a long-term coexistence with the chytrids.Therefore,the skin microbiota of this resistant species warrant investigation,along with other factors that can affect the microbiota.Among the 149 newts sampled in their natural habitats in Hong Kong,China,putative antifungal bacteria were found in all individuals.There were 314 amplicon sequence variants distributed over 25 genera of putative antifungal bacteria;abundant ones included Acinetobacter,Flavobacterium,and Novosphingobium spp.The skin microbiota compositions were strongly influenced by the inter-site geographical distances.Despite inter-site differences,we identified some core skin microbes across sites that could be vital to P.hongkongensis.The dominant cores included the family Comamonadaceae,family Chitinophagaceae,and class Betaproteobacteria.Moreover,habitat elevation and host sex also exhibited significant effects on skin microbiota compositions.The antifungal bacteria found on these newts offer an important resource for conservation against chytridiomycosis,such as developing probiotic treatments for susceptible species.展开更多
Considerable progress has been made in understanding the responses of amphibians to climate change,with successful research carried out on climate change-associated shifts in amphibian phenology,elevational distributi...Considerable progress has been made in understanding the responses of amphibians to climate change,with successful research carried out on climate change-associated shifts in amphibian phenology,elevational distributions and amphibian-parasite interactions.We review and synthesize the literature on this topic,emphasizing acutely lethal,sublethal,indirect and positive effects of climate change on amphibians,and major research gaps.For instance,evidence is lacking on poleward shifts in amphibian distributions and on changes in body sizes and morphologies of amphibians in response to climate change.We have limited information on amphibian thermal tolerances,thermal preferences,dehydration breaths,opportunity costs of water conserving behaviors and actual temperature and moisture ranges amphibians experience.Even when much of this information is available,there remains little evidence that climate change is acutely lethal to amphibians.This suggests that if climate change is contributing to declines,it might be through effects that are not acutely lethal,indirect,or both,but evidence in support of this suggestion is necessary.In fact,evidence that climate change is directly contributing to amphibian declines is weak,partly because researchers have not often ruled out alternative hypotheses,such as chytrid fungus or climate-fungus interactions.Consequently,we recommend that amphibian-climate research shift from primarily inductive,correlational approach as to studies that evaluate alternative hypotheses for declines.This additional rigor will require interdisciplinary collaborations,estimates of costs and benefits of climate change to amphibian fitness and populations,and the integration of correlative field studies,experiments on‘model’amphibian species,and mathematical and functional,physiological models.展开更多
Considerable controversy exists concerning whether or not climate changes(particularly global warming)are causing outbreaks of a lethal amphibian pathogen,the chytrid fungus Batrachochytrium dendrobatidis(Longcore,Pes...Considerable controversy exists concerning whether or not climate changes(particularly global warming)are causing outbreaks of a lethal amphibian pathogen,the chytrid fungus Batrachochytrium dendrobatidis(Longcore,Pessier&D.K.Nichols 1999).In the present study,groups of Panamanian golden frogs(Atelopus zeteki Dunn,1993),a critically endangered amphibian thought to be nearly extinct in Panama,were exposed to varying dosages of zoospores of Batrachochytrium dendrobatidis,temperatures and hydric environments in order to learn whether this species is susceptible to this pathogen and,if so,how environmental factors affect survival.This pathogen proved to be highly lethal for A.zeteki.Frogs exposed to a dosage of 100 Bd zoospores survived significantly(P<0.0001)longer than those that had been exposed to 104 or 106 zoospores.Exposed frogs housed at 23℃survived significantly(P<0.0001)longer than those that were housed at 17℃.Exposed frogs held in dry conditions survived significantly longer than those in wet conditions(P<0.0001).As a laboratory study,these results do not directly test hypotheses about the relation between climate change and the decline of these frogs in the field,but they inform the discussion about how environmental conditions can have an impact on the interaction between a susceptible amphibian and this pathogen.These data do not support the contention that rising global temperatures are necessary to cause the death of amphibians infected with this pathogen because the pathogen was equally lethal at 17 as at 23℃,and frogs at the warmer temperature lived significantly longer than those at the cooler one.展开更多
文摘In urban landscape, amphibians face many challenges in order to sustain their populations, such as road mortality and infection of pathogenic Batrachochytrium dendrobatidis (Bd). Bd infection has been reported to cause significant mortality;however, its current distribution in the state of New Jersey remains unknown. In spring, amphibians emerge from their wintering group and migrate to nearby breeding ponds or vernal pools. Their migration pathway is often intercepted by the dense network of human transportation which leads to extirpation. This study aims to investigate potential mortality caused by human transportation and the infected rate of Bd fungus on the amphibian populations at a suburban area in central New Jersey. Twenty-four pitfall traps were installed to collect amphibians. A total of 687 organisms representing 7 amphibian species were recorded during the 73-day study period. Four of the 7 species were selected to test for Bd infection;73.6% of the amphibian skin swabs showed positive results of infection. However, Bd was not detected in water and soil samples collected around the study areas. The results of this study suggested that road mortality and pathogenic Bd might have tremendously impacted the urban amphibian populations and might have been the major causes of the current trend of amphibian population decline, particularly in the urban area.
基金Acknowledgements We thank Prof. An Martel at Ghent University for providing positive control samples for Bs detection by PCR. We thank Zhiqing Xu at the Chongqing Museum of Natural History for assisting with sampling. This research was supported by grants from The Ministry of Science and Technology of China （2013FYl10300） and the Beijing Natural Science Foundation （code： 5132026）.
文摘For the last decade, chytridiomycosis was considered to be caused by a single species of fungus, Batrachochytrium dendrobatidis （Bd）, but a second chytrid species, Batrachochytrium salamandrivorans （Bs）, was recently isolated from an in- fected Salamandra salamandra in the Netherlands. To date, Bs has only been found in the Netherlands. To assess whether Bs is present in China, we analyzed a total of 665 samples, including 425 wild samples, 41 preserved specimens, and 199 captive sam- pies, from 30 different species, including both urodeles and anurans. Our sample sites covered 15 provinces in China. All of the samples tested negative for Bs, resulting in a 95% confidence limit for a prevalence of 0.6%. The absence of Bs observed in this large-scale survey in China has significant implications for amphibian conservation and for border trade management strategies intended to control amphibian diseases. We strongly recommend the continued close monitoring of Bs to verify the status of this potentially devastating amphibian fungus in China .
基金supported by the Start-Up Fund granted to S.Y.W.S.by the University of Hong KongThis work was approved by the Agriculture,Fisheries and Conservation Department[Permit no.:(29)in AF GR CON 09/51Pt.7]of the HKSAR Government.
文摘Chytridiomycosis,an infectious skin disease caused by the chytrid fungi,Batrachochytrium dendrobatidis and B.salamandrivorans,poses a significant threat to amphibian biodiversity worldwide.Antifungal bacteria found on the skin of chytrid-resistant amphibians could potentially provide defense against chytridiomycosis and lower mortality rates among resistant individuals.The Hong Kong newt(Paramesotriton hongkongensis)is native to East Asia,a region suspected to be the origin of chytrids,and has exhibited asymptomatic infection,suggesting a long-term coexistence with the chytrids.Therefore,the skin microbiota of this resistant species warrant investigation,along with other factors that can affect the microbiota.Among the 149 newts sampled in their natural habitats in Hong Kong,China,putative antifungal bacteria were found in all individuals.There were 314 amplicon sequence variants distributed over 25 genera of putative antifungal bacteria;abundant ones included Acinetobacter,Flavobacterium,and Novosphingobium spp.The skin microbiota compositions were strongly influenced by the inter-site geographical distances.Despite inter-site differences,we identified some core skin microbes across sites that could be vital to P.hongkongensis.The dominant cores included the family Comamonadaceae,family Chitinophagaceae,and class Betaproteobacteria.Moreover,habitat elevation and host sex also exhibited significant effects on skin microbiota compositions.The antifungal bacteria found on these newts offer an important resource for conservation against chytridiomycosis,such as developing probiotic treatments for susceptible species.
基金supported by grants from the Chinese Academy of Sciences(code:kscx2-yw-z-1021)the National Science Foundation of China(code:31172111)+1 种基金supported by grants from the United States Environmental Protection Agency(STAR R833835,RD-83518801-0)the United States Department of Agriculture(NRI 2009-35102-0543).
文摘Considerable progress has been made in understanding the responses of amphibians to climate change,with successful research carried out on climate change-associated shifts in amphibian phenology,elevational distributions and amphibian-parasite interactions.We review and synthesize the literature on this topic,emphasizing acutely lethal,sublethal,indirect and positive effects of climate change on amphibians,and major research gaps.For instance,evidence is lacking on poleward shifts in amphibian distributions and on changes in body sizes and morphologies of amphibians in response to climate change.We have limited information on amphibian thermal tolerances,thermal preferences,dehydration breaths,opportunity costs of water conserving behaviors and actual temperature and moisture ranges amphibians experience.Even when much of this information is available,there remains little evidence that climate change is acutely lethal to amphibians.This suggests that if climate change is contributing to declines,it might be through effects that are not acutely lethal,indirect,or both,but evidence in support of this suggestion is necessary.In fact,evidence that climate change is directly contributing to amphibian declines is weak,partly because researchers have not often ruled out alternative hypotheses,such as chytrid fungus or climate-fungus interactions.Consequently,we recommend that amphibian-climate research shift from primarily inductive,correlational approach as to studies that evaluate alternative hypotheses for declines.This additional rigor will require interdisciplinary collaborations,estimates of costs and benefits of climate change to amphibian fitness and populations,and the integration of correlative field studies,experiments on‘model’amphibian species,and mathematical and functional,physiological models.
基金the ISZS international research program Biological Consequences of Global Change(BCGC)sponsored by Bureau of International Cooperation,Chinese Academy of Sciences(GJHZ200810).
文摘Considerable controversy exists concerning whether or not climate changes(particularly global warming)are causing outbreaks of a lethal amphibian pathogen,the chytrid fungus Batrachochytrium dendrobatidis(Longcore,Pessier&D.K.Nichols 1999).In the present study,groups of Panamanian golden frogs(Atelopus zeteki Dunn,1993),a critically endangered amphibian thought to be nearly extinct in Panama,were exposed to varying dosages of zoospores of Batrachochytrium dendrobatidis,temperatures and hydric environments in order to learn whether this species is susceptible to this pathogen and,if so,how environmental factors affect survival.This pathogen proved to be highly lethal for A.zeteki.Frogs exposed to a dosage of 100 Bd zoospores survived significantly(P<0.0001)longer than those that had been exposed to 104 or 106 zoospores.Exposed frogs housed at 23℃survived significantly(P<0.0001)longer than those that were housed at 17℃.Exposed frogs held in dry conditions survived significantly longer than those in wet conditions(P<0.0001).As a laboratory study,these results do not directly test hypotheses about the relation between climate change and the decline of these frogs in the field,but they inform the discussion about how environmental conditions can have an impact on the interaction between a susceptible amphibian and this pathogen.These data do not support the contention that rising global temperatures are necessary to cause the death of amphibians infected with this pathogen because the pathogen was equally lethal at 17 as at 23℃,and frogs at the warmer temperature lived significantly longer than those at the cooler one.
