Next‐generation monitoring of aquatic biodiversity using environmental DNA metabarcoding

Global biodiversity in freshwater and the oceans is declining at high rates. Reliable tools for assessing and monitoring aquatic biodiversity, especially for rare and secretive species, are important for efficient and timely management. Recent advances in DNA sequencing have provided a new tool for species detection from DNA present in the environment. In this study, we tested whether an environmental DNA (eDNA) metabarcoding approach, using water samples, can be used for addressing significant questions in ecology and conservation. Two key aquatic vertebrate groups were targeted: amphibians and bony fish. The reliability of this method was cautiously validated in silico, in vitro and in situ. When compared with traditional surveys or historical data, eDNA metabarcoding showed a much better detection probability overall. For amphibians, the detection probability with eDNA metabarcoding was 0.97 (CI = 0.90–0.99) vs. 0.58 (CI = 0.50–0.63) for traditional surveys. For fish, in 89% of the studied sites, the number of taxa detected using the eDNA metabarcoding approach was higher or identical to the number detected using traditional methods. We argue that the proposed DNA‐based approach has the potential to become the next‐generation tool for ecological studies and standardized biodiversity monitoring in a wide range of aquatic ecosystems.     

Environmental DNA metabarcoding of wild flowers reveals diverse communities of terrestrial arthropods

Terrestrial arthropods comprise the most species‐rich communities on Earth, and grassland flowers provide resources for hundreds of thousands of arthropod species. Diverse grassland ecosystems worldwide are threatened by various types of environmental change, which has led to decline in arthropod diversity. At the same time, monitoring grassland arthropod diversity is time‐consuming and strictly dependent on declining taxonomic expertise. Environmental DNA (eDNA) metabarcoding of complex samples has demonstrated that information on species compositions can be efficiently and non‐invasively obtained. Here, we test the potential of wild flowers as a novel source of arthropod eDNA. We performed eDNA metabarcoding of flowers from several different plant species using two sets of generic primers, targeting the mitochondrial genes 16S rRNA and COI. Our results show that terrestrial arthropod species leave traces of DNA on the flowers that they interact with. We obtained eDNA from at least 135 arthropod species in 67 families and 14 orders, together representing diverse ecological groups including pollinators, parasitoids, gall inducers, predators, and phytophagous species. Arthropod communities clustered together according to plant species. Our data also indicate that this experiment was not exhaustive, and that an even higher arthropod richness could be obtained using this eDNA approach. Overall, our results demonstrate that it is possible to obtain information on diverse communities of insects and other terrestrial arthropods from eDNA metabarcoding of wild flowers. This novel source of eDNA represents a vast potential for addressing fundamental research questions in ecology, obtaining data on cryptic and unknown species of plant‐associated arthropods, as well as applied research on pest management or conservation of endangered species such as wild pollinators.     

BIODIVERSITY RESEARCH: Geographical linkages between threats and imperilment in freshwater fish in the Mediterranean Basin

Aim The level of imperilment of mediterranean freshwater fish is among the highest recorded for any group of organisms evaluated to date. Here, we describe the geographical patterns in the incidence of threats affecting mediterranean freshwater fish and test whether the effects of specific threats are spatially related to the degree of imperilment of fish faunas. Location The Mediterranean Basin Biome. Methods From the IUCN Red List, we recorded the six main threats to 232 endemic freshwater fish species. We used data on fish distributions from IUCN to characterize the spatial patterns in the incidence of threats (as percentage of species affected) through multivariate statistics. We studied the relationships between threat incidence and two estimators of imperilment (proportion of species threatened and an index of extinction risk) at two spatial scales (10 × 10 km and basins) using partial least squares regressions (PLSR) that incorporated the effects of species richness and mean range size. Results The main axis of variation in the incidence of threats to freshwater fish split areas mainly affected by invasive species from those areas where species are threatened by pollution and agriculture. Wherever invasive species and water extraction were predominant threats, fish assemblages consistently tended to be more imperilled. Main conclusions As far as we know, this is the first large‐scale analysis on the spatial relationships between the incidence of threats and level of imperilment of any taxonomic group. Our results highlight the primary role of invasive species and water extraction as drivers of native fish declines in the Mediterranean Basin. Large‐scale patterns described here should be generated by local‐scale impacts of both threats on fish biodiversity, widely reported in Mediterranean areas. Because all the species under concern are endemic, control of invasive species and reducing overexploitation of freshwater resources should be conservation priorities for mediterranean freshwater systems.     

Neglected taxonomy of rare desert fishes: congruent evidence for two species of leatherside chub

Conservation biologists rely heavily on taxonomy to set the scope for biological monitoring and recovery planning of rare or threatened species. Yet, taxonomic boundaries are seldom evaluated as falsifiable hypotheses that can be statistically tested. Here, we examine species boundaries in leatherside chub (Teleostei, Cyprinidae), an imperiled desert fish native to the Bonneville Basin and upper Snake River drainages of western North America. Recent molecular data hint that this fish could be composed of two distinct taxa that are geographically separated into northern and southern species. To formally test this hypothesis, we evaluated leatherside chub using several different categories of species concepts, including criteria dependent on phylogenetic, morphological, and ecological data. We found that leatherside chub is composed of two reciprocally monophyletic clades (candidate species) characterized by numerous fixed genetic differences for both mitochondrial and nuclear DNA markers; mtDNA sequence divergence between the two clades approached 8%. The candidate species also showed significant differences in cranial shape, revealed by morphometric analysis. Finally, controlled growth and foraging experiments using representative populations from each clade show that candidate species appear to be locally adapted to the thermal environments where they now occur. Combined, these three lines of evidence support the hypothesis that leatherside chub is composed of two species. Moreover, all lines of evidence place these two species within the genusLepidomeda, a group consisting of three additional species of endangered spinedace fishes, and one extinct species, all native to the Colorado River system. Hence, we elevate the two clades of leatherside chub to distinct species status (Lepidomeda copeiin the north andL. aliciaein the south), and argue that each warrants independent conservation and recovery action.     

Living quarters of a living fossil—Uncovering the current distribution pattern of the rediscovered Hula painted frog (Latonia nigriventer) using environmental DNA

One of the greatest challenges of effective conservation measures is the correct identification of sites where rare and elusive organisms reside. The recently rediscovered Hula painted frog (Latonia nigriventer) has not been seen for many decades and was therefore categorized extinct. Since its rediscovery in 2011, individuals from the critically endangered species have been found, with great effort, only in four restricted sites. We applied the environmental DNA (eDNA) approach to search for new populations of the Hula painted frog in suitable aquatic habitats. We further used the eDNA data to classify the landscape factors associated with the species distribution and to predict its suitable habitats. We sampled 52 aquatic sites in the Hula Valley during the spring of 2015 and 2016 and amplified the samples with a species‐specific qPCR assay. DNA of the Hula painted frog was detected in 22 of the sites, all of which clustered within three main areas. A boosting classification model showed that soil type, vegetation cover and the current and former habitats are all key predictors of the frog's current distribution. Intriguingly, the habitat suitability models reveal a high affinity of the species to its long‐lost habitat of the historical wetlands. Our findings encourage a series of informed searches for new populations of this threatened frog and provide guidance for future conservation management programmes. In the era of global conservation crisis of amphibians, developing the eDNA approach, a reliable detection method for many critically endangered and elusive amphibians, is of particular importance.     

Conservation tool or threatening process? management implications of interactions of cattle with vegetation and land at the Vale of Belvoir reserve

A recently purchased private reserve of high conservation value has been grazed in summer by cattle since the early nineteenth century. We ask whether the cattle are causing continuing damage and whether they are necessary to maintain any conservation values. We used five‐year‐old exclosures to determine the effects of cattle on wetland vegetation, mapped damage to soils and landforms and mapped cattle dung deposition in relation to the distributions of rare and threatened plant species. Cattle impacts on wetland plants were minor. Cattle damage to landforms by pugging and bank collapse was frequent near unfenced water bodies. Rare and threatened species were largely on well‐drained ground, while cattle dung was concentrated in wetlands and near water bodies. We conclude that cattle grazing is impacting some conservation values and is not necessary for conservation purposes. Destocking should be accompanied by careful monitoring of threatened plant populations. If necessary, alternative planned disturbances can provide regeneration niches for rare and threatened plants.     

Age and size at maturity: A quantitative review of diet‐induced reaction norms in insects

Optimality models predict that diet‐induced bivariate reaction norms for age and size at maturity can have diverse shapes, with the slope varying from negative to positive. To evaluate these predictions, we perform a quantitative review of relevant data, using a literature‐derived database of body sizes and development times for over 200 insect species. We show that bivariate reaction norms with a negative slope prevail in nearly all taxonomic and ecological categories of insects as well as in some other ectotherm taxa with comparable life histories (arachnids and amphibians). In insects, positive slopes are largely limited to species, which feed on discrete resource items, parasitoids in particular. By contrast, with virtually no meaningful exceptions, herbivorous and predatory insects display reaction norms with a negative slope. This is consistent with the idea that predictable resource depletion, a scenario selecting for positively sloped reaction norms, is not frequent for these insects. Another source of such selection—a positive correlation between resource levels and juvenile mortality rates—should similarly be rare among insects. Positive slopes can also be predicted by models which integrate life‐history evolution and population dynamics. As bottom‐up regulation is not common in most insect groups, such models may not be most appropriate for insects.     

Multi-species monitoring of rare wetland fishes should account for imperfect detection of sampling devices

Accuracy in estimating occupancy of a threatened species is important for conservation but false absences bias many monitoring programs. Imperfect detection is especially relevant to surveys of rare wetland fishes which are often small-bodied and cryptic. Many factors influence probability of detection, including fish size and abundance, habitat characteristics and sampling devices. Imperfect detection can be addressed by accounting for probability of detection when estimating occupancy by modelling detection/non-detection data collected in replicate surveys. Three ecological specialists were once common in habitats associated with Lake Alexandrina at the terminus of the Murray–Darling Basin, Australia. The threatened Murray Hardyhead (Craterocephalus fluviatilis), Southern Pygmy Perch (Nannoperca australis) and Yarra Pygmy Perch (N. obscura) are now rare in the region following population collapses during a prolonged drought, and ongoing monitoring aims to assess their statuses for management purposes. This study compares probability of detection of the rare wetland fishes and cohabiting species during 2 years of multi-species monitoring using contrasting sampling devices (fyke and seine). The findings suggest large variations in estimated probability of detection can occur between devices for Murray Hardyhead and Southern Pygmy Perch. Yarra Pygmy Perch was undetected during the study. Overall, the findings show multi-species monitoring programs using a single sampling device may wrongly estimate the occupancy of a target fish. By accounting for imperfect detection, multi-species monitoring programs will improve inferences regarding population status, recovery and habitat quality of fishes to more accurately inform wetland management.     

Genome size and extinction risk in vertebrates

The hypothesis of 'selfish DNA' is tested for the case of animals using the relation between genome size and conservation status of a given species. In contrast to plants, where the larger genome was previously shown to increase the likelihood of extinction, the picture is more complicated in animals. At the within-families and within-orders levels, the larger genome increases the risk of extinction only in reptiles and birds (which have the smallest genomes among tetrapods). In fishes and amphibians, the effect is caused by the higher taxonomic levels (above order). In several phylogenetic lineages of anamniotes, there is a correlation between a higher fraction of threatened species and a lower number of extant species in a lineage with the larger genome. In mammals, no effect was observed at any taxonomic level. The obtained data support the concept of hierarchical selection. It is also shown that, in plants and reptiles, the probability of being threatened increases from less than 10% to more than 80% with the increase in genome size, which can help in establishing conservation priorities.     

Fish communities diverge in species but converge in traits over three decades of warming

Describing the spatial and temporal dynamics of communities is essential for understanding the impacts of global environmental change on biodiversity and ecosystem functioning. Trait‐based approaches can provide better insight than species‐based (i.e. taxonomic) approaches into community assembly and ecosystem functioning, but comparing species and trait dynamics may reveal important patterns for understanding community responses to environmental change. Here, we used a 33‐year database of fish monitoring to compare the spatio‐temporal dynamics of taxonomic and trait structure in North Sea fish communities. We found that the majority of variation in both taxonomic and trait structure was explained by a pronounced spatial gradient, with distinct communities in the southern and northern North Sea related to depth, sea surface temperature, salinity and bed shear stress. Both taxonomic and trait structure changed significantly over time; however taxonomically, communities in the south and north diverged towards different species, becoming more dissimilar over time, yet they converged towards the same traits regardless of species differences. In particular, communities shifted towards smaller, faster growing species with higher thermal preferences and pelagic water column position. Although taxonomic structure changed over time, its spatial distribution remained relatively stable, whereas in trait structure, the southern zone of the North Sea shifted northward and expanded, leading to homogenization. Our findings suggest that global environmental change, notably climate warming, will lead to convergence towards traits more adapted for novel environments regardless of species composition.     

Threat Assessment and Conservation Prioritization of the Herpetofauna of El Salvador

We applied the IUCN Red List method for threat assessment to the amphibians and reptiles of El Salvador, the smallest Central American country. Seventy-six out of 130 species were found to be threatened or endangered at the national level. In general, most threatened taxa were aquatic organisms in lowland habitats or cloud-forest specialists in highland areas. The IUCN method was biased by collecting effort and was unable to classify 25 species that were categorized as ȁ8data deficientȁ9. We used the number and distribution of threatened species and a complementarity analysis to identify departments in El Salvador that require higher priority for conservation action. We applied a method for evaluating inventory completeness to our data set, and used species from reasonably well-surveyed taxonomic groups (Anura and Sauria) to carryout the complementarity analysis. The anurans (frogs) and saurians (lizards) had been inventoried relatively completely in 10 of 14 departments. The department with the most threatened species (35 of 76 threatened amphibians and reptiles) is Santa Ana, where many threatened species occur in pine-oak and cloud forest in Montecristo National Park.     

Aquatic biodiversity assessment for the lazy

The world is covered in DNA. In any ecosystem, extracellular DNA fragments can be found that once formed the genomes of a variety of micro‐ and macroorganisms. A few years ago, it was proposed to use this environmental DNA (eDNA) as a source of information on local vertebrate biodiversity (Ficetola et al. 2008 ; Taberlet et al. 2012 ). This idea offered an elegant solution to take up the gauntlet of rapidly increasing monitoring needs. Coupled with barcoding efforts, it promised to be cost‐efficient in many respects, for example man‐hours and taxonomic expertise. Ecologists and conservation biologists with an interest in aquatic ecosystems have enthusiastically adopted and pioneered this new method, producing dozens of eDNA studies. Most of these studies have, however, focused on a single or a few aquatic species. In this issue of Molecular Ecology, Valentini et al. ( 2016 ) move the field a step further by demonstrating that metabarcoding approaches – which simultaneously target large groups of organisms such as amphibians or fish – can match and sometimes even outperform other inventory methods.     

Taxonomic challenges in freshwater fishes: a mismatch between morphology and DNA barcoding in fish of the north‐eastern part of the Congo basin

This study evaluates the utility of DNA barcoding to traditional morphology‐based species identifications for the fish fauna of the north‐eastern Congo basin. We compared DNA sequences (COI) of 821 samples from 206 morphologically identified species. Best match, best close match and all species barcoding analyses resulted in a rather low identification success of 87.5%, 84.5% and 64.1%, respectively. The ratio ‘nearest‐neighbour distance/maximum intraspecific divergence’ was lower than 1 for 26.1% of the samples, indicating possible taxonomic problems. In ten genera, belonging to six families, the number of species inferred from mtDNA data exceeded the number of species identified using morphological features; and in four cases indications of possible synonymy were detected. Finally, the DNA barcodes confirmed previously known identification problems within certain genera of the Clariidae, Cyprinidae and Mormyridae. Our results underscore the large number of taxonomic problems lingering in the taxonomy of the fish fauna of the Congo basin and illustrate why DNA barcodes will contribute to future efforts to compile a reliable taxonomic inventory of the Congo basin fish fauna. Therefore, the obtained barcodes were deposited in the reference barcode library of the Barcode of Life Initiative.     

鄱阳湖鱼类多样性的时空变化特征研究

研究基于2010年4月、7月和2018年8月、2019年5月在鄱阳湖9个区域的鱼类多样性调查数据,分析鱼类物种多样性、功能多样性和分类差异指数的时空变化以及其与环境之间的关系,了解鄱阳湖近十年来鱼类群落多样性的时空变化特征。结果显示, 2010年和2018—2019年分别调查到鱼类74种和93种,群落结构差异显著(P<0.05),差异贡献率最高的物种为短颌鲚、似鳊、鲫、光泽黄颡鱼和鲤;水温、总悬浮物和叶绿素等环境因素具有显著的年际和季节差异(P<0.05)。与2010年相比, 2018—2019年鱼类物种多样性和功能多样性指数有一定增加,分类差异指数没有显著变化。分类差异指数的随机检验显示(Randomization test),与2010年相比, 2018—2019年位于95%概率置信范围下方的区域增加。水温、总悬浮物和叶绿素等环境因素对物种多样性、功能多样性和分类差异指数有显著的影响(P<0.05)。结果表明,近十年来,鄱阳湖鱼类群落结构发生明显改变,但是小型鱼类依旧是优势种,鱼类群落小型化明显,主要原因可能是过度捕捞的影响。同时,鄱阳湖的人类活动干扰增大,鄱阳县...     

Environmental DNA (eDNA): Powerful technique for biodiversity conservation

Environmental DNA metabarcoding is a non-invasive method for discovering and identifying rare and endangered species in a variety of ecosystems, including aquatic environments, based on the retrieval of genetic traces emitted into the environment by animals. Environmental (e) DNA research has grown in popularity over the last decade as a result of a rise in the number of studies that employ DNA taken from the environment, particularly in freshwater and marine ecosystems. In terms of detecting diversity patterns, we may claim that DNA retrieved from the environment (eDNA) is altering the game. For resource management in fisheries, information on species composition and biomass/abundance of commercially and noncommercially harvested species is critical. The eDNA is a truly non-invasive method that inflicts no damage on the species or habitats under study even during sampling, the eDNA technique never harms any ecosystems or threatened species. This novel molecular method never affects any endangered species or ecosystem during sampling. Environmental DNA analysis has become more widely accepted and is used in the detection of the presence and absence of aquatic macrofauna, such as freshwater and marine fish. This review study may aid researchers in better understanding the current state of eDNA technology. Despite the fact that various scientists have used eDNA to investigate the worldwide biodiversity of aquatic environments, no one in India is focusing on this new technology. We conclude that the eDNA technique has the potential to become a next-generation tool for biodiversity research and aquatic ecosystem conservation.     

Environmental DNA enables detection of terrestrial mammals from forest pond water

Terrestrial animals must have frequent contact with water to survive, implying that environmental DNA (eDNA) originating from those animals should be detectable from places containing water in terrestrial ecosystems. Aiming to detect the presence of terrestrial mammals using forest water samples, we applied a set of universal PCR primers (MiMammal, a modified version of fish universal primers) for metabarcoding mammalian eDNA. The versatility of MiMammal primers was tested in silico and by amplifying DNAs extracted from tissues. The results suggested that MiMammal primers are capable of amplifying and distinguishing a diverse group of mammalian species. In addition, analyses of water samples from zoo cages of mammals with known species composition suggested that MiMammal primers could successfully detect mammalian species from water samples in the field. Then, we performed an experiment to detect mammals from natural ecosystems by collecting five 500‐ml water samples from ponds in two cool‐temperate forests in Hokkaido, northern Japan. MiMammal amplicon libraries were constructed using eDNA extracted from water samples, and sequences generated by Illumina MiSeq were subjected to data processing and taxonomic assignment. We thereby detected multiple species of mammals common to the sampling areas, including deer (Cervus nippon), mouse (Mus musculus), vole (Myodes rufocanus), raccoon (Procyon lotor), rat (Rattus norvegicus) and shrew (Sorex unguiculatus). Many previous applications of the eDNA metabarcoding approach have been limited to aquatic/semiaquatic systems, but the results presented here show that the approach is also promising even for forest mammal biodiversity surveys.     

Barriers to hybridisation and their conservation implications for a highly threatened Australian fish species

Hybridisation and introgression are natural phenomena that may lead to the transfer of adaptive alleles from one species to another and increased species diversity. At the same time, hybridisation and subsequent introgression threaten many species world‐wide through the loss of genetic and species diversity. In Australia, introgressive hybridisation between native and alien species has not typically been considered a significant threat to native biodiversity because of the taxonomic distance between native and alien biota. However, many native fish have been introduced outside their natural range. Recently, four taxa in the genus Melanotaenia have been nationally listed as threatened due to introgressive hybridisation with introduced Melanotaenia splendida. We examined pre‐ and post‐zygotic barriers to hybridisation between M. splendida and one of these threatened taxa—Running River rainbowfish (RRR)—to assess the potential for hybridisation to occur. We used dichotomous mate choice experiments to examine pre‐zygotic barriers and mating experiments to examine post‐zygotic barriers. Size was not a significant predictor of the proportion of time subjects spent with a potential mate, nor was there any significant difference in the amount of time subjects spent with potential mates of their own or the opposite species. Eggs from hybrid pairings with female RRR had a slightly higher hatching rate than those from hybrid pairings with female M. splendida, but neither were significantly different from intraspecies crosses. We could not identify any definite barriers to hybridisation, demonstrating that the introduction of “native” fish species outside their natural range poses a higher risk of hybridisation than previously thought. We call for better education around the consequences of moving “native” fish and the development of rapid response plans to deal with recently established alien populations of Australian fish species in order to prevent future extinctions due to introgressive hybridisation.     

Metabarcoding of shrimp stomach content: Harnessing a natural sampler for fish biodiversity monitoring

Given their positioning and biological productivity, estuaries have long represented key providers of ecosystem services and consequently remain under remarkable pressure from numerous forms of anthropogenic impact. The monitoring of fish communities in space and time is one of the most widespread and established approaches to assess the ecological status of estuaries and other coastal habitats, but traditional fish surveys are invasive, costly, labour intensive and highly selective. Recently, the application of metabarcoding techniques, on either sediment or aqueous environmental DNA, has rapidly gained popularity. Here, we evaluate the application of a novel, high‐throughput DNA‐based monitoring tool to assess fish diversity, based on the analysis of the gut contents of a generalist predator/scavenger, the European brown shrimp, Crangon crangon. Sediment and shrimp samples were collected from eight European estuaries, and DNA metabarcoding (using both 12S and COI markers) was carried out to infer fish assemblage composition. We detected 32 teleost species (16 and 20, for 12S and COI, respectively). Twice as many species were recovered using metabarcoding than by traditional net surveys. By comparing and interweaving trophic, environmental DNA and traditional survey‐based techniques, we show that the DNA‐assisted gut content analysis of a ubiquitous, easily accessible, generalist species may serve as a powerful, rapid and cost‐effective tool for large‐scale, routine estuarine biodiversity monitoring.     

Human activity is altering the world’s zoogeographical regions

Zoogeographical regions, or zooregions, are areas of the Earth defined by species pools that reflect ecological, historical and evolutionary processes acting over millions of years. Consequently, researchers have assumed that zooregions are robust and unlikely to change on a human timescale. However, the increasing number of human‐mediated introductions and extinctions can challenge this assumption. By delineating zooregions with a network‐based algorithm, here we show that introductions and extinctions are altering the zooregions we know today. Introductions are homogenising the Eurasian and African mammal zooregions and also triggering less intuitive effects in birds and amphibians, such as dividing and redefining zooregions representing the Old and New World. Furthermore, these Old and New World amphibian zooregions are no longer detected when considering introductions plus extinctions of the most threatened species. Our findings highlight the profound and far‐reaching impact of human activity and call for identifying and protecting the uniqueness of biotic assemblages.     

中国两栖动物受威胁现状评估

为了了解我国两栖动物受威胁现状和致危因素, 进而制定相关的保护措施和开展国际合作, 本文依据中国两栖动物野生种群与生境现状, 利用《IUCN物种红色名录濒危等级和标准》(3.1版)和《IUCN物种红色名录标准在国家或地区的应用指南》(4.0版), 对中国已知的408种两栖动物的濒危状况进行了评估, 并编制了《中国两栖动物红色名录》。评估结果表明: 中国两栖动物有1种灭绝, 1种区域灭绝, 受威胁的两栖动物共计176种, 占评估物种总数的43.1%, 明显高于《IUCN濒危物种红色名录》(2015)的物种受威胁率(30.8%)。中国两栖动物特有种272种, 其中48.9%属于受威胁物种。中国两栖动物受威胁比例最高的目是有尾目(63.4%), 明显高于无尾目(39.0%); 受威胁比例最高的科是隐鳃鲵科(Cryptobranchidae) (仅有1种, 100%受威胁), 小鲵科(Hynobiidae) (86.7%)和叉舌蛙科(Dicroglossidae) (78.1%)。有11个省区的受威胁物种数占本省区两栖动物物种总数的30%及以上, 前3位分别是四川(40.8%)、广西(39.2%)和云南(37%)。中国大多数两栖动物物种分布在西南山地和华南地区, 以海拔2,000 m以下区域为主。栖息地退化或丧失、捕捉、环境污染列受威胁两栖动物致危因子的前3位。鉴于中国两栖动物区系的复杂性和独特性, 进一步加强两栖动物资源调查、种群和生境监测及相关科学研究, 仍是今后一段时期开展两栖动物多样性保护和濒危物种拯救行动的关键性基础工作。