Application of eDNA Metabarcoding for Detecting Anura in North China

eDNA metabarcoding is an advanced method formonitoring biodiversityproposed in recent years.By analyzing DNA in water,soil and sediment samples,the technology obtains species distribution and population quantity information.It was found that macrobarcode technology is more accurate than the traditional method in measuring the species richness of some groups.In Europe,America and South America,the relia bility of this technology in monitoring amphibian diversity in the wild was studied,and it was found to be better than traditional biodiversity monitoring methods in detecting species diversity.At present,amphibian monitoring mainly depends on various traditional methods,such as transects,drift fence traps,artificial shelters and mark-recapture.These monitoring techniques have many shortcomings,such as low accuracy and strong subjectivity of study results.These technologies have poor effects on rare,invasive and endangered species with strong concealment ability,low density and strong seasonality and are difficult to implement in sites inaccessible to people.Traditional monitoring technology also requires considerable investment of human and material resources,and the economic cost is relatively high,while eDNA metabarcoding ismore efficient and less costly,so it is important to use eDNA meta barcoding in amphibian monitoring in China.In this study,the eDNA meta barcoding and traditional line transect method(TLTM)were used to study the characteristics of the two methods in the Beijing-Tianjin-Hebeiregion.Repeated samplingwas conducted on 58 waterbodies in July 2019 and June 2020.After sequencing the samples using highthroughput sequencing technology,the differences between metabarcoding and commonly used TLTM surveys in detecting the diversity of four amphibians in North China were assessed.Our results showed that eDNA meta barcoding is more sensitive to the detection of the four amphibian species in the sampling area,and the combined use of eDNA metabarcoding and TLTM can improve the survey results of amphibians in the survey area to the greatest extent.In addition,in the process of species classification and identification of metabarcoding results,7 species of reptiles were detected,indicating that eDNA metabarcoding is also useful to detect reptiles.The results of this study indicate that metabarcoding in combination with TLTM can accurately estimate the diversityof amphibians in a short-term survey in North China and is also useful in reptile species detection.

Characterization of Skin Symbiotic Bacteria of Sympatric Amphibians in Southeastern China

The fungal infection called chytridiomycosis,caused by Batrachochytrium dendrobatidis(Bd),has given rise to dramatic declines or extinctions of many amphibian species around the world;however,in Asia,this disease has shown a low zoospore load or scant mortality.One potential reason for this may be that certain unique community structures of amphibian skin symbiosis contribute to the outcome of the disease;nevertheless,we know very little about the microbiota in this region. In this study,we used skin swabs of five sympatric amphibian species that have various habitat preferences in Lishui,Zhejiang Province,a place in southeastern China,to explore the skin bacterial communities by using 16 S rRNA amplicon sequencing.We detected a total of 1020 OTUs,belonging to 17 phyla,among which Proteobacteria,Firmicutes,Actinobacteria and Bacteroidetes dominated all five host species.Enterobacteriaceae and Exiguobacteraceae and the genera Escherichia and Exiguobacterium belonging to these two families were identified as the most abundant taxa on our focal species.The alpha diversity was significantly lower on the terrestrial species,and also the highly enriched Proteobacteria was found on the terrestrial species,Rana zhenhaiensis,whereas Actinobacteria,Bacteroidetes,Cyanobacteria and Firmicutes were more abundant on aquatic species than on the terrestrial species.Our results suggest that both host species and habitat sites are important factors driving skin microbial diversity and composition and that amphibians in China may harbour unique skin bacterial communities.This study helps elucidate amphibian skin microbial ecology,and with further efforts,the specific mechanism of the interaction between Bd and host amphibians in China could be elucidated.

Sheep grazing causes shift in sex ratio and cohort structure of Brandt’s vole:Implication of their adaptation to food shortage

Livestock grazing has been demonstrated to affect the population abundance of small rodents in grasslands,but the causative mechanism of grazing on demographic parameters,particularly the age structure and sex ratio,is rarely investigated.In this study,we examined the effects of sheep grazing on the cohort structure and sex ratio of Brandt’s vole(Lasiopodomys brandtii)in Inner Mongolia of China by using large manipulative experimental enclosures during 2010-2013.Our results indicated that sheep grazing significantly decreased the proportion of the spring-born cohort,but increased the proportion of the summer-born cohort.Grazing increased the proportion of males in both spring and summer cohorts.In addition,we found a negative relation between population density and the proportion of the overwinter cohort.Our results suggest that a shift in the cohort structure and the sex ratio may be an important strategy for small rodents to adapt to changes in food resources resulting from livestock grazing.