Amphibians Testing Negative for Batrachochytrium dendrobatidis and Batrachochytrium salamandrivorans on the Qinghai-Tibetan Plateau,China

A disease caused by the fungi Batrachochytrium dendrobatidis（Bd） and Batrachochytrium salamandrivorans（Bsal） is responsible for recent worldwide declines and extinctions of amphibian populations.The Qinghai-Tibetan Plateau（QTP） is aglobal biodiversity hotspot,yet little is known about the prevalence of Bd and Bsal in this region.In this study,we collected 336 non-invasive skin swabs from wild amphibians（including an exotic amphibian species） on the QTP.In addition,to assess the historical prevalence of Bd and Bsal on the QTP,we collected 117 non-invasive skin swabs from museum-archived amphibian samples（from 1964-1982） originating from the QTP.Our results showed all samples to be negative for Bd and Bsal.The government should ban the potentially harmful introduction of non-native amphibian species to the QTP and educate the public about the impacts of releasing exotic amphibians from chytridinfected areas into native environments of the QTP.

The origin of invasion of an alien frog species in Tibet, China

Identifying the origins of alien species has important implications for effectively controlling the spread of alien species. The black-spotted frog Pelophylax nigromaculatus, originally from East Asia, has become an alien species on the Tibetan Plateau （TP）. In this study, we collected 300 individuals of P. nigromaculatus from 13 native regions and 2 invasive regions （including Nyingchi and Lhasa） on the TP. To identify the source region of the TP introductions, we sequenced portions of the mitochondrial cyt b gene. We sequenced a -600-bp portion of the mitochondrial cyt b gene to identify 69 haplotypes （124 polymorphic sites） in all sampled populations. According to the network results, we suggest that the P. nigromaculatus found on the TP was most likely originated from Chongqing by human introduction. Furthermore, we found that the genetic diversity was significantly lower for invasive than for native sites due to founder effects. Our study provides genetic evidence that this alien species invaded the cold environment of high elevations and expanded the distribution of P. nigromaculatus in China.

A survey for Batrachochytrium salamandrivorans in Chinese amphibians

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 .

Effects of temperature and hydric environment on survival of the Panamanian Golden Frog infected with a pathogenic chytrid fungus

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.