Global and endemic Asian lineages of the emerging pathogenic fungus Batrachochytrium dendrobatidis widely infect amphibians in China

Aim Panzootic chytridiomycosis caused by the chytrid fungus Batrachochytrium dendrobatidis (Bd) is the proximate cause of rapid amphibian declines across diverse biomes. While the origin of Bd remains unclear, increasingly the global trade in amphibians is associated with the spread of the infection. Global samples of Bd genotypes from previously unsampled regions are essential to test this hypothesis. In this paper, we present a study of the prevalence and phylogeny of Bd in both invasive and native amphibian species in markets and in the wild in ten provinces of China. Location China. Method We used a nested PCR assay to amplify the ribosomal internal transcribed spacer region of Bd followed by sequencing. Result Our results showed 246 of 2734 amphibians testing positive for Bd, with 157 positive samples in the wild (7.6%) and 89 in markets (13.5%). 30 haplotypes of Bd were identified, including 20 first detections. Introduced Lithobates catesbeianus had the highest prevalence of infection and the largest number of Bd haplotypes in both the wild and markets. Phylogenetic analysis based on 73 haplotypes (57 from Asia and 16 from other continents) showed that a unique, well‐supported, basal haplotype is present in Asia. Phylogeographical analyses revealed that some geographical structure exists amongst a subset of global haplotypes. Main conclusions Strains of the basal haplotype infected Babina pleuraden, an amphibian that is endemic to China, and Andrias japonicus, endemic to Japan, showing that Southeast Asia harbours a novel endemic lineage of amphibian‐associated Bd. Our data suggest that Bd in Asia pre‐dates the expansion of a globalized lineage of Bd, a finding that is indicative of a broader association of amphibians and chytrids than has previously been recognized. More genetic data from Bd isolates are needed to reveal the phylogenetic relationship of Bd in China compared to that found elsewhere.     

Novel,panzootic and hybrid genotypes of amphibian chytridiomycosis associated with the bullfrog trade

Global amphibian declines are linked with the presence of specific, highly virulent genotypes of the emerging fungal disease chytridiomycosis caused by Batrachochytrium dendrobatidis (Bd) known as the global panzootic lineage (Bd‐GPL). The global trade in amphibians for human consumption is suspected to have facilitated emergence of the disease, but evidence to support this is largely lacking. Here, we investigated the role the Lithobates catesbeianus (North American bullfrog) trade in spreading Bd genotypes by comparing strains associated with L. catesbeianus to a global panel using 36 sequenced loci from multiple chromosomal regions. Most bullfrogs were infected with Bd‐GPL genotypes, but we also detected novel, highly divergent Bd genotypes (Bd‐Brazil) from a live bullfrog in a US market and from native Brazilian anurans in the Atlantic Forest where bullfrogs are widely farmed. Sexual reproduction was also detected for the first time in Bd in the form of a hybrid genotype between the Bd‐GPL and Bd‐Brazil lineages in the Atlantic Forest. Despite the demonstration that ribosomal RNA types in Bd fail to undergo concerted evolution (over 20 sequence types may be found in a single strain), the Bd‐GPL and Bd‐Brazil lineages form largely separate clusters of related internal transcribed spacer (ITS) RNA sequences. Using ITS sequences, we then demonstrate the presence of Bd‐Brazil in Japan, primarily on invasive L. catesbeianus. The finding that Bd is capable of sexual reproduction between panzootic and endemic genotypes emphasizes the risk of international wildlife trade as a source of additional Bd epizootics owing to hybridization.     

Amphibian chytridiomycosis in Japan: distribution,haplotypes and possible route of entry into Japan

A serious disease of amphibians caused by the chytrid fungus Batrachochytrium dendrobatidis was first found in Japan in December 2006 in imported pet frogs. This was the first report of chytridiomycosis in Asia. To assess the risk of pandemic chytridiomycosis to Japanese frogs, we surveyed the distribution of the fungus among captive and wild frog populations. We established a nested PCR assay that uses two pairs of PCR primers to amplify the internal transcribed spacer (ITS) region of a ribosomal RNA cassette to detect mild fungal infections from as little as 0.001 pg (1 fg) of B. dendrobatidis DNA. We collected swab samples from 265 amphibians sold at pet shops, 294 bred at institutes and 2103 collected at field sites from northern to southwestern Japan. We detected infections in native and exotic species, both in captivity and in the field. Sequencing of PCR products revealed 26 haplotypes of the B. dendrobatidis ITS region. Phylogenetic analysis showed that three of these haplotypes were specific to the Japanese giant salamander (Andrias japonicus) and appeared to have established a commensal relationship with this native amphibian. Many other haplotypes were carried by alien amphibians. The highest genetic diversity of B. dendrobatidis was found in the American bullfrog (Rana catesbeiana). Some strains of B. dendrobatidis appeared to be endemic to Japanese native amphibians, but many alien strains are being introduced into Japan via imported amphibians. To improve chytridiomycosis risk management, we must consider the risk of B. dendrobatidis changing hosts as a result of anthropogenic disturbance of the host‐specific distribution of the fungus.     

Early-spring survey for Batrachochytrium dendrobatidis in wild Rana dybowskii in Heilongjiang Province, China

Batrachochytrium dendrobatidis has been investigated worldwide because of its importance in population declines in multiple species of amphibians; however, little is known regarding the disease status of all native amphibian species in China. The present study is the first survey of chytridiomycosis in free-ranging amphibian populations in China, and it examined the possible presence of B. dendrobatidis in Rana dybowskii in northeastern China (Heilongjiang Province). R. dybowskii is mainly distributed in the northeast part of China and is intensively hunted for human consumption, making populations vulnerable to extirpation in the event of additional stresses from disease epidemics. The survey was performed in early spring of 2008, using a PCR assay, histological examination of skin samples, and zoospore culture. In total, 191 frogs were examined; thus, a 95% confidence limit for prevalence of 1.57% was selected. Our results demonstrate that R. dybowskii is currently free from chytridiomycosis in Heilongjiang, even though the natural conditions of the sampling sites are suitable for the occurrence of B. dendrobatidis. Central and local governments should implement strict management measures to prevent the escape of non-native commercial amphibian species into this area, which might endanger local populations of native species.     

Dr Jekyll and Mrs Hyde: Risky hybrid sex by amphibian‐parasitizing chytrids in the Brazilian Atlantic Forests

In their article in this issue of Molecular Ecology, Jenkinson et al. ( 2016 ) and colleagues address a worrying question—how could arguably the most dangerous pathogen known to science, Batrachochytrium dendrobatidis (Bd), become even more virulent? The answer: start having sex. Jenkinson et al. present a case for how the introduction into Brazil of the globally invasive lineage of Bd, BdGPL, has disrupted the relationship between native amphibians and an endemic Bd lineage, BdBrazil. BdBrazil is hypothesized to be native to the Atlantic Forest and so have a long co‐evolutionary history with biodiverse Atlantic Forest amphibian community. The authors suggest that this has resulted in a zone of hybrid Bd genotypes which are potentially more likely to cause fatal chytridiomycosis than either parent lineage. The endemic–nonendemic Bd hybrid genotypes described in this study, and the evidence for pathogen translocation via the global amphibian trade presented, highlights the danger of anthropogenic pathogen dispersal. This research emphasizes that biosecurity regulations may have to refocus on lineages within species if we are to mitigate against the danger of new, possibly hypervirulent genotypes of pathogens emerging as phylogeographic barriers are breached.     

First Record of Batrachochytrium dendrobatidis Infecting Four Frog Families from Peninsular Malaysia

The fungal pathogen Batrachochytrium dendrobatidis (Bd) infects amphibians on every continent where they occur and is linked to the decline of over 200 amphibian species worldwide. At present, only three published Bd surveys exist for mainland Asia, and Bd has been detected in South Korea alone. In this article, we report the first survey for Bd in Peninsular Malaysia. We swabbed 127 individuals from the six amphibian families that occur on Peninsular Malaysia, including two orders, 27 genera, and 47 species. We detected Bd on 10 out of 127 individuals from four of five states and five of 11 localities, placing the 95% confidence interval for overall prevalence at 4–14%. We detected no variation in Bd prevalence among regions, elevations, or taxonomic groups. The infection intensity ranged from 1 to 157,000 genome equivalents. The presence of Bd infections in native species without clinical signs of disease suggests that Bd may be endemic to the region. Alternately, Bd may have been introduced from non-native amphibians because of the substantial amphibian food trade in Peninsular Malaysia. Under both scenarios, management efforts should be implemented to limit the spread of non-native Bd and protect the tremendous amphibian diversity in Peninsular Malaysia.     

Endemic Asian Chytrid Strain Infection in Threatened and Endemic Anurans of the Northern Western Ghats,India

The Western Ghats of India harbors a rich diversity of amphibians with more than 77% species endemic to this region. At least 42% of the endemic species are threatened due to several anthropogenic stressors. However, information on amphibian diseases and their impacts on amphibian populations in this region are scarce. We report the occurrence of Batrachochytridium dendrobatidis (Bd), an epidermal aquatic fungal pathogen that causes chytridiomycosis in amphibians, from the Western Ghats. In the current study we detected the occurrence of a native Asian Bd strain from three endemic and threatened species of anurans, Bombay Night Frog Nyctibatrachus humayuni, Leith''s Leaping Frog Indirana leithii and Bombay Bubble Nest Frog Raorchestes bombayensis, for the first time from the northern Western Ghats of India based on diagnostic nested PCR, quantitative PCR, DNA sequencing and histopathology. While, the Bd infected I. leithii and R. bombayensis did not show any external symptoms, N. humayuni showed lesions on the skin, browning of skin and sloughing. Sequencing of Bd 5.8S ribosomal RNA gene, and the ITS1 and ITS2 regions, revealed that the current Bd strain is related to a haplotype endemic to Asia. Our findings confirm the presence of Bd in northern Western Ghats and the affected amphibians may or may not show detectable clinical symptoms. We suggest that the significance of diseases as potential threat to amphibian populations of the Western Ghats needs to be highlighted from the conservation point of view.     

浙江东部牛蛙的自然种群及潜在危害

牛蛙(Rana catesbeiana)的入侵已成为一些本地两栖类种群数量下降或灭绝的主要因素之一。1959年牛蛙被引入中国大陆,但直到1990年才开始在国内大范围饲养。牛蛙的自然种群在国内一直未见报道。我们于2003年9—11月调查了浙江省东部5区3县的牛蛙种群,发现在岱山、秀山、六横及佛渡岛上有牛蛙分布,共捕获23只牛蛙,包括4只成年个体,18个亚成体和1只蝌蚪。于2004年1月和2月在岱山捕获28只蝌蚪。结果显示：(1)牛蛙的蝌蚪能在当地越冬成活,说明牛蛙在上述4岛成功地建立了自然种群;(2)牛蛙主要分布于水库、池塘和溪流,牛蛙的生境与6种当地蛙有部分重叠;(3)养殖时管理不善造成的牛蛙逃逸,以及牛蛙价格过低而导致养殖户将牛蛙弃置野外可能是牛蛙入侵的主要原因。牛蛙对当地蛙的潜在威胁很大,开展牛蛙的分布、食性和种群动态研究是当务之急。     

Immmunological Clearance of <Emphasis Type="Italic">Batrachochytrium dendrobatidis</Emphasis> Infection at a Pathogen-optimal Temperature in the Hylid Frog <Emphasis Type="Italic">Hypsiboas crepitans</Emphasis>

Amphibian declines worldwide have been linked to the fungal disease chytridiomycosis. Its causative agent (Batrachochytrium dendrobatidis, hereafter Bd), however, also infects many nondeclining species. Experimental infections have shown species-specific and temperature-dependent frog responses to Bd infection. Although Bd infection may be eliminated by housing amphibians at temperatures above those tolerated by the fungus, the question of whether frogs can eliminate infection under more favorable conditions remains unanswered. Repeated diagnostics using real-time polymerase chain reaction (rt–PCR) assays of postmetamorphic individuals at 28, 38, 45, 53, and 62 days after exposure demonstrated that Hypsiboas crepitans is able to clear infection within a few weeks at 23°C. Thus, we demonstrate a temperature-independent and likely immunological mechanism for the clearance of Bd in a resistant amphibian species. Future studies are needed to determine the generality of this mechanism among amphibians and to describe the immune factors affecting different outcomes of Bd exposure including resistance to infection, tolerance of infection, and clearance of infection.     

High Prevalence of Batrachochytrium dendrobatidis in Wild Populations of Lowland Leopard Frogs Rana yavapaiensis in Arizona

Batrachochytrium dendrobatidis (Bd) is a fungus that can potentially lead to chytridiomycosis, an amphibian disease implicated in die-offs and population declines in many regions of the world. Winter field surveys in the last decade have documented die-offs in populations of the lowland leopard frog Rana yavapaiensis with chytridiomycosis. To test whether the fungus persists in host populations between episodes of observed host mortality, we quantified field-based Bd infection rates during nonwinter months. We used PCR to sample for the presence of Bd in live individuals from nine seemingly healthy populations of the lowland leopard frog as well as four of the American bullfrog R. catesbeiana (a putative vector for Bd) from Arizona. We found Bd in 10 of 13 sampled populations. The overall prevalence of Bd was 43% in lowland leopard frogs and 18% in American bullfrogs. Our results suggest that Bd is widespread in Arizona during nonwinter months and may become virulent only in winter in conjunction with other cofactors, or is now benign in these species. The absence of Bd from two populations associated with thermal springs (water >30°C), despite its presence in nearby ambient waters, suggests that these microhabitats represent refugia from Bd and chytridiomycosis.     

Mitigating amphibian chytridiomycosis with bioaugmentation: characteristics of effective probiotics and strategies for their selection and use

Probiotic therapy through bioaugmentation is a feasible disease mitigation strategy based on growing evidence that microbes contribute to host defences of plants and animals. Amphibians are currently threatened by the rapid global spread of the pathogen, Batrachochytrium dendrobatidis (Bd), which causes the disease chytridiomycosis. Bioaugmentation of locally occurring protective bacteria on amphibians has mitigated this disease effectively in laboratory trials and one recent field trial. Areas still naïve to Bd provide an opportunity for conservationists to proactively implement probiotic strategies to prevent further amphibian declines. In areas where Bd is endemic, bioaugmentation can facilitate repatriation of susceptible amphibians currently maintained in assurance colonies. Here, we synthesise the current research in amphibian microbial ecology and bioaugmentation to identify characteristics of effective probiotics in relation to their interactions with Bd, their host, other resident microbes and the environment. To target at‐risk species and amphibian communities, we develop sampling strategies and filtering protocols that result in probiotics that inhibit Bd under ecologically relevant conditions and persist on susceptible amphibians. This filtering tool can be used proactively to guide amphibian disease mitigation and can be extended to other taxa threatened by emerging infectious diseases.     

Known and estimated distribution in Mexico of Batrachochytrium dendrobatidis,a pathogenic fungus of amphibians

Chytridiomycosis caused by fungus Batrachochytrium dendrobatidis (Bd) is one of the decline global causes of amphibians. Currently, it is distributed throughout a broad range of climates and ecosystems around the world. An epidemic wave of chytridiomycosis began in North America, resulting in population decline and local extinction of many species, reconfiguring species composition of amphibian communities in the Americas. In Mexico, Bd has caused an amphibian population decrease, and its potential distribution area has not been determined. We reviewed the number of species infected, obtaining Bd frequency of infection by land use and vegetation type, and by elevation range. We examined the known distribution of Bd, estimated the potential distribution, and obtained the bioclimate variables relevant for Bd. Our results indicate that in Mexico, Bd has been detected in 78 species of amphibians in 10 families, from 29 different land use and vegetation types, with cloud forest having the highest number of cases (139) and infected species (15). Bd occurs over an elevation range of 1–3,300 m asl and is most frequent at 1,200–1,500 m asl (36%). In addition to the regions previously described as suitable for Bd, our model included desert, coastal, and tropical forest regions, revealing an increase in the area where amphibians could be at risk of infection. Distribution of Bd is mainly associated with temperature of the wettest quarter and potential evapotranspiration of the warmer quarter. We offer an estimate of the ideal conditions for Bd in Mexico, also information for future studies on Bd and the conservation of amphibians. Abstract in Spanish is available with online material.     

Retrospective Survey of Museum Specimens Reveals Historically Widespread Presence of Batrachochytrium dendrobatidis in China

Chytridiomycosis, caused by the chytrid fungus Batrachochytrium dendrobatidis (Bd), has been implicated in amphibian population declines worldwide. However, no amphibian declines or extinctions associated with Bd have been reported in Asia. To investigate the history of this pathogen in China, we examined 1,007 museum-preserved amphibian specimens of 80 species collected between 1933 and 2009. Bd was detected in 60 individuals (6.0%), with the earliest case of Bd infection occurring in one specimen of Bufo gargarizans and two Fejervarya limnocharis, all collected in 1933 from Chongqing, southwest China. Although mainly detected in non-threatened native amphibians, Bd was also found in four endangered species. We report the first evidence of Bd for Taiwan and the first detection of Bd in the critically endangered Chinese giant salamander (Andrias davidianus). Bd appears to have been present at a low rate of infection since at least the 1930s in China, and no significant differences in prevalence were detected between decades or provinces, suggesting that a historical steady endemic relationship between Bd and Chinese amphibians has occurred. Our results add new insights on the global emergence of Bd and suggest that this pathogen has been more widely distributed in the last century than previously believed.     

Diet and Prey Selection of the Invasive American Bullfrog(Lithobates catesbeianus) in Southwestern China

Invasive predators have been widely regarded as one of the principle drivers of the global decline of amphibians, which are among the most threatened vertebrate taxon on Earth. The American bullfrog(Lithobates catesbeianus) is identified as one of the most successful vertebrate invaders and has caused the decline or extinction of some native amphibians in many regions and countries including China. Based on field surveys and stomach content analyses, we examined the diet composition of the invasive bullfrog for the first time in two invaded populations in Yunnan Province, southwestern China, a region of global conservation priority, during the breeding season from 2008 to 2014. Additionally, we conducted the first quantitative study on the prey selection of this global invader among their invaded ranges after controlling for the local anuran assemblage and other aquatic preys in the environment. Our results showed that the range of food items in the stomachs of bullfrogs spanned more than 30 species belonging to ten taxonomic classes. Both of post-metamorphosis individuals and juveniles preyed upon native frogs, independent of the bullfrog's body size and mouth width. Importantly, Jacobs' selection index showed a bullfrog preference for the Yunnan pond frog(Babina pleuraden), one native endemic anuran with population decline, in terms of both food volume and occurrence. We therefore provided direct evidence on the predation impact of the invasive bullfrog on an endemic anuran and urged further efforts to prevent the dispersal of this invader into more fragile habitats to reduce their negative impacts on native amphibians.     

昆明地区滇蛙与昭觉林蛙同域分布种群的生境利用比较

现有两栖类生境研究报道多局限于定性描述,缺乏定量数据和统计分析支撑。以蛙的发现点为圆心,作半径1m的样圆,测量12个生态因子。调查共记录滇蛙(Ranapleuraden)133只和昭觉林蛙(Ranachaochiaoensis)62只。采用两独立样本t-检验和非参数Mann-WhitneyU-检验比较两种蛙对同一生境的利用,结果表明,在干燥草地生境仅最高植物高度差异显著;湿润草地生境至水源距离和水百分比差异极显著,水草百分比和湿泥百分比差异显著;水体生境各种生态因子的差异均不显著。主成分分析结果显示,在不同生境中滇蛙和昭觉林蛙所选择的因子往往相同或者顺序颠倒,但这些因子的值几乎均是反向分离的,即小生境不相同。两种蛙的生境利用各有偏好。滇蛙日间活动主要在水体,而昭觉林蛙则在湿润草地和干燥草地。两种蛙对泥地生境利用都少。不同体长的滇蛙对水体生境利用度均较高。昭觉林蛙随着体长增加,对隐蔽条件好的湿润草地和干燥草地生境利用度增加,对水体的利用度减少。     

Assessing the Threat of Amphibian Chytrid Fungus in the Albertine Rift: Past,Present and Future

Batrachochytrium dendrobatidis (Bd), the cause of chytridiomycosis, is a pathogenic fungus that is found worldwide and is a major contributor to amphibian declines and extinctions. We report results of a comprehensive effort to assess the distribution and threat of Bd in one of the Earth’s most important biodiversity hotspots, the Albertine Rift in central Africa. In herpetological surveys conducted between 2010 and 2014, 1018 skin swabs from 17 amphibian genera in 39 sites across the Albertine Rift were tested for Bd by PCR. Overall, 19.5% of amphibians tested positive from all sites combined. Skin tissue samples from 163 amphibians were examined histologically; of these two had superficial epidermal intracorneal fungal colonization and lesions consistent with the disease chytridiomycosis. One amphibian was found dead during the surveys, and all others encountered appeared healthy. We found no evidence for Bd-induced mortality events, a finding consistent with other studies. To gain a historical perspective about Bd in the Albertine Rift, skin swabs from 232 museum-archived amphibians collected as voucher specimens from 1925–1994 were tested for Bd. Of these, one sample was positive; an Itombwe River frog (Phrynobatrachus asper) collected in 1950 in the Itombwe highlands. This finding represents the earliest record of Bd in the Democratic Republic of Congo. We modeled the distribution of Bd in the Albertine Rift using MaxEnt software, and trained our model for improved predictability. Our model predicts that Bd is currently widespread across the Albertine Rift, with moderate habitat suitability extending into the lowlands. Under climatic modeling scenarios our model predicts that optimal habitat suitability of Bd will decrease causing a major range contraction of the fungus by 2080. Our baseline data and modeling predictions are important for comparative studies, especially if significant changes in amphibian health status or climactic conditions are encountered in the future.     

Invasive North American bullfrogs transmit lethal fungus <Emphasis Type="Italic">Batrachochytrium dendrobatidis</Emphasis> infections to native amphibian host species

Invasive species can be a threat to native species in several ways, including transmitting lethal infections caused by the parasites they carry. However, invasive species may also be plagued by novel and lethal infections they acquire when invading, making inferences regarding the ability of an invasive host to vector disease difficult from field observations of infection and disease. This is the case for the pathogenic fungus Batrachochytrium dendrobatidis (Bd) in Europe and one invasive host species, the North American bullfrog Lithobates catesbeianus, hypothesized to be responsible for vectoring lethal infection to European native amphibians. We tested this hypothesis experimentally using the alpine newt Ichthyosaura alpestris as our model native host. Our results show that infected bullfrog tadpoles are effective vectors of Bd. Native adult newts co-housed with experimentally infected bullfrog tadpoles became Bd infected (molecular and histological tests). Moreover, the exposed adult newts suffered mortality while the majority of infected bullfrog tadpoles survived until metamorphosis. These results cannot resolve the historical role of alien species in establishing the distribution of Bd across Europe or other regions in the world where this species was introduced, but they show its potential role as a Bd reservoir capable of transmitting lethal infections to native amphibians. Finally, our results also suggest that the removal of infected bullfrogs from aquatic environments may serve to reduce the availability of Bd in European amphibian communities, offering another justification for bullfrog eradication programmes that are currently underway or may be considered.     

Landscape epidemiology of Batrachochytrium dendrobatidis in central California

Amphibian chytridiomycosis (caused by Batrachochytrium dendrobatis; Bd) was first identified in 1998 and has since been implicated in numerous amphibian declines worldwide. Most researchers have since investigated broad‐scale geographic and taxonomic occurrences of the pathogen in tropical lotic or cool montane systems. In this study, we analyzed how environmental factors, land use practices, and landscape structure may affect the dynamics of the pathogen's distribution in a landscape dominated by lentic systems within a region of Mediterranean climate. We quantified the occurrence of Bd testing the six resident amphibian species that occur in 54 isolated perennial and ephemeral ponds in central California between May and June annually from 2004 to 2007. The geographic distribution of Bd within the landscape varied markedly between years. Inter‐annual variation in climate affected the pond landscape structure indicating that climate conditions indirectly influence the distribution of the pathogen. Fourteen ponds, 12 perennial and 2 ephemeral, were positive for Bd≥3 yr of the study and were treated as Bd hotpots for comparative purposes. Occurrences of Bd within the landscape were spatially autocorrelated and ponds within ~1000–1500 m of Bd hotspots were more likely to test positive. Local land use, (presence/absence of grazing or recreational activity and developed lands), did not influence Bd status of a pond, indicating that the most likely means of Bd transmission between ponds may be waterfowl and/or amphibians.     

Endemic and introduced haplotypes of Batrachochytrium dendrobatidis in Japanese amphibians: sink or source?

The global emergence of the amphibian chytrid pathogen Batrachochytrium dendrobatidis (Bd) is one of the most compelling, and troubling, examples of a panzootic. Only discovered in 1998, Bd is now recognized as a proximate driver of global declines in amphibian diversity and is now widely acknowledged as a key threatening process for this ancient class of vertebrates. Moreover, Bd has become a member of a small group of highly virulent multihost pathogens that are known to have had effects on entire vertebrate communities and the ecosystem‐level effects of Bd‐driven amphibian declines are starting to emerge as a consequence of regional decreases in amphibian diversity. Despite the speed at which this species of aquatic chytrid has become a focus of research efforts, major questions still exist about where Bd originated, how it spreads, where it occurs and what are Bd’s effects on populations and species inhabiting different regions and biomes. In this issue, Goka et al. (2009 ) make an important contribution by publishing the first nationwide surveillance for Bd in Asia. Although previous data had suggested that amphibians in Asia are largely uninfected by Bd, these surveys were limited in their extent and few firm conclusions could be drawn about the true extent of infection. Goka et al. herein describe a systematic surveillance of Japan for both native and exotic species in the wild, as well as amphibians housed in captivity, using a Bd‐specific nested PCR reaction on a sample of over 2600 amphibians. Their results show that Bd is widely prevalent in native species across Japan in at least three of the islands that make up the archipelago, proving for the first time that Asia harbours Bd.     

Amphibian richness patterns in Atlantic Forest areas invaded by American bullfrogs

The relationship between invasion success and native biodiversity is central to biological invasion research. New theoretical and analytical approaches have revealed that spatial scale, land‐use factors and community assemblages are important predictors of the relationship between community diversity and invasibility and the negative effects of invasive species on community diversity. In this study we assess if the abundance of Lithobates catesbeianus, the American bullfrog, negatively affects the richness of native amphibian species in Atlantic Forest waterbodies in Brazil. Although this species has been invading Atlantic Forest areas since the 1930s, studies that estimate the invasion effects upon native species diversity are lacking. We developed a model to understand the impact of environmental, spatial and species composition gradients on the relationships between bullfrogs and native species richness. We found a weak positive relationship between bullfrog abundance and species richness in invaded areas. The path model revealed that this is an indirect relationship mediated by community composition gradients. Our results indicate that bullfrogs are more abundant in certain amphibian communities, which can be species‐rich. Local factors describing habitat heterogeneity were the main predictors of amphibian species richness and composition and bullfrog abundance. Our results reinforce the important role of habitats in determining both native species diversity and potential invasibility.