Environmental influences on local amphibian diversity: the role of floods on river basins

We tested two hypotheses about boundary units and seven about environmental control of species diversity in order to explain geographical trends in the richness of amphibian species in the Mediterranean watershed of the southern coast of the Iberian Peninsula. The number of amphibian species tends to decrease from west to east. The longitudinal trend in the richness of amphibian species actually occurs on passing from one basin to another, but there is not any longitudinal trend within the basins. Multivariate analyses confirmed that the disturbances of episodic river-basin floodings were the principal factor which controls the richness of amphibian species. They explained 94.8% of the observed variations in the richness of amphibian species in this area, according to the intermediate disturbance hypothesis.We propose hydrographic basins as suitable geographical units for further biogeographical analysis and for considering the role of disturbances produced by floods in the environmental control of species diversity.     

滇西北中甸的两栖爬行动物

滇西北中甸地区共有两栖类13种（亚种）,隶属于2目5科;爬行动物11种（亚种）,隶属于1目2亚目5科。区系成分以东洋界西南区的种类占主导地位,两栖类占84．6％,爬行类占72．7％。区系特点表现为：区系组成单一却特有率高,成分古老又兼具年轻特点,南北动物交汇形成多样化。两栖爬行动物的种群分布与植被类型具有密切的相关性;为适应环境动物形态发生了较多变化。认为中甸地区是动物地理区划中的一关键地区,其两栖爬行类动物的调查及分类研究工作尚需进一步深入。     

Isolation and cDNA cloning of cholecystokinin from the skin of Rana nigrovittata

Many neuroendocrine peptides that are distributed in amphibian gastrointestinal tract and central nervous system are also found in amphibian skins, and these peptides are classified into skin-gut-brain triangle peptides, such as bombesins, gastrin-releasing peptides. Cholecystokinins (CCKs) are neuroendocrine peptides known for their production in the gastrointestinal tract and central nervous system of mammalians. Several CCKs have been identified from two amphibians, Rana catesbeiana and Xenopus laevis. These amphibian CCKs are found to be express in brain and in the gastrointestinal tract, but not in skin. In the current report, a cholecystokinin (CCK) isoform was identified from skin secretions of the frog, Rana nigrovittata. Its amino acid sequence is RVDGNSDQKAVIGAMLAKDLQTRKAGSSTGRYAVLPNR PVIDPTHRINDRDYMGWMDF, which is the same with that of CCK from R. catesbeiana. Four different cDNAs (GenBank accession nos. EF608063-6) encoding CCK precursors were cloned from the cDNA library of the skin of R. nigrovittata. The present data demonstrated that amphibian CCK could also be expressed in gastrointestinal tract, central nervous system and skin as other amphibian skin-gut-brain triangle peptides.     

Using amphibians in laboratory studies: precautions against the emerging infectious disease chytridiomycosis

The African clawed frog Xenopus laevis is by far the most widely used amphibian species in laboratories. In the wild, X. laevis is an asymptomatic carrier of an emerging infectious disease called chytridiomycosis. The vector is the chytrid fungus Batrachochytrium dendrobatidis (Bd), which has devastating effects on wild amphibian populations around the world. The impact of Bd on the metabolism of X. laevis has not been comprehended yet. However, even if asymptomatic, an infection is likely to affect the individual's physiology, immunology, development, reproduction and overall response to stress from a purely medical point of view, which will introduce noise and therefore increase variance within experimental groups of X. laevis. This could have implications on the scientific results from studies using this species. Here, we review the current knowledge on treatments of infected amphibians and propose a hygiene protocol adapted to laboratory populations and amphibian husbandry. Following the presented sanitation guidelines could further prevent the spread of Bd and probably of other amphibian pathogens. The sanitation guidelines will help to reduce the impact of amphibian husbandry on natural populations and must be considered a crucial contribution to amphibian conservation, as today 32% of all amphibians are considered threatened.     

Evolution of allantoinase and allantoicase involved in urate degradation in liver peroxisomes. A rapid purification of amphibian allantoinase and allantoicase complex, its subunit locations of the two enzymes, and its comparison with fish allantoinase and allantoicase

Allantoinase and allantoicase are located in the same protein molecule in amphibian liver, whereas the two enzymes are different proteins in marine fish and invertebrate liver (Takada, Y., and Noguchi, T. (1983) J. Biol. Chem. 258, 4762-4764). The amphibian enzyme was rapidly purified from frog liver by using its following characteristics. 1) The enzyme binds to the intracellular membranes in the hypotonic solution. 2) The membrane-bound enzyme is not solubilized by the detergent. 3) The membrane-bound enzyme is solubilized by oxaloacetate. The electrophoresis of the purified enzyme gave a single protein band in the absence of sodium dodecyl sulfate, and gave two protein bands with molecular weights of 48,000 and 54,000, respectively, in the presence of sodium dodecyl sulfate. With a specific antibody raised against each subunit, allantoinase activity was found to be from the large subunit, and allantoicase activity to be from the small subunit. This amphibian allantoinase and allantoicase complex was compared with allantoinase and allantoicase purified from fish liver. Fish allantoinase was a single peptide and fish allantoicase was composed of two identical subunits. Fish allantoinase had an identical molecular weight with amphibian large (allantoinase) subunit and the subunit of fish allantoicase with amphibian small (allantoicase) subunit. These results suggest that the evolution of fish to amphibian resulted in the dissociation of allantoicase into subunits and in the association of allantoinase with allantoicase. The two enzymes are lost by further evolution.     

Synergistic effects of the invasive Chinese tallow (Triadica sebifera) and climate change on aquatic amphibian survival

Changes in climate and the introduction of invasive species are two major stressors to amphibians, although little is known about the interaction between these two factors with regard to impacts on amphibians. We focused our study on an invasive tree species, the Chinese tallow (Triadica sebifera), that annually sheds its leaves and produces leaf litter that is known to negatively impact aquatic amphibian survival. The purpose of our research was to determine whether the timing of leaf fall from Chinese tallow and the timing of amphibian breeding (determined by weather) influence survival of amphibian larvae. We simulated a range of winter weather scenarios, ranging from cold to warm, by altering the relative timing of when leaf litter and amphibian larvae were introduced into aquatic mesocosms. Our results indicate that amphibian larvae survival was greatly affected by the length of time Chinese tallow leaf litter decomposes in water prior to the introduction of the larvae. Larvae in treatments simulating warm winters (early amphibian breeding) were introduced to the mesocosms early in the aquatic decomposition process of the leaf litter and had significantly lower survival compared with cold winters (late amphibian breeding), likely due to significantly lower dissolved oxygen levels. Shifts to earlier breeding phenology, linked to warming climate, have already been observed in many amphibian taxa, and with most climate models predicting a significant warming trend over the next century, the trend toward earlier breeding should continue if not increase. Our results strongly suggest that a warming climate can interact with the effects of invasive plant species, in ways we have not previously considered, to reduce the survival of an already declining group of organisms.     

Rapid Response to Evaluate the Presence of Amphibian Chytrid Fungus (Batrachochytrium dendrobatidis) and Ranavirus in Wild Amphibian Populations in Madagascar

We performed a rapid response investigation to evaluate the presence and distribution of amphibian pathogens in Madagascar following our identification of amphibian chytrid fungus (Batrachochytrium dendrobatidis, Bd) and ranavirus in commercially exported amphibians. This targeted risk-based field surveillance program was conducted from February to April 2014 encompassing 12 regions and 47 survey sites. We simultaneously collected amphibian and environmental samples to increase survey sensitivity and performed sampling both in wilderness areas and commercial amphibian trade facilities. Bd was not detected in any of 508 amphibian skin swabs or 68 water filter samples, suggesting pathogen prevalence was below 0.8%, with 95% confidence during our visit. Ranavirus was detected in 5 of 97 amphibians, including one adult Mantidactylus cowanii and three unidentified larvae from Ranomafana National Park, and one adult Mantidactylus mocquardi from Ankaratra. Ranavirus was also detected in water samples collected from two commercial amphibian export facilities. We also provide the first report of an amphibian mass-mortality event observed in wild amphibians in Madagascar. Although neither Bd nor ranavirus appeared widespread in Madagascar during this investigation, additional health surveys are required to disentangle potential seasonal variations in pathogen abundance and detectability from actual changes in pathogen distribution and rates of spread. Accordingly, our results should be conservatively interpreted until a comparable survey effort during winter months has been performed. It is imperative that biosecurity practices be immediately adopted to limit the unintentional increased spread of disease through the movement of contaminated equipment or direct disposal of contaminated material from wildlife trade facilities. The presence of potentially introduced strains of ranaviruses suggests that Madagascar''s reptile species might also be threatened by disease. Standardized population monitoring of key amphibian and reptile species should be established with urgency to enable early detection of potential impacts of disease emergence in this global biodiversity hotspot.     

Selecting for extinction: nonrandom disease-associated extinction homogenizes amphibian biotas

Studying the patterns in which local extinctions occur is critical to understanding how extinctions affect biodiversity at local, regional and global spatial scales. To understand the importance of patterns of extinction at a regional spatial scale, we use data from extirpations associated with a widespread pathogenic agent of amphibian decline, Batrachochytrium dendrobatidis ( Bd ) as a model system. We apply novel null model analyses to these data to determine whether recent extirpations associated with Bd have resulted in selective extinction and homogenization of diverse tropical American amphibian biotas. We find that Bd -associated extinctions in this region were nonrandom and disproportionately, but not exclusively, affected low-occupancy and endemic species, resulting in homogenization of the remnant amphibian fauna. The pattern of extirpations also resulted in phylogenetic homogenization at the family level and ecological homogenization of reproductive mode and habitat association. Additionally, many more species were extirpated from the region than would be expected if extirpations occurred randomly. Our results indicate that amphibian declines in this region are an extinction filter, reducing regional amphibian biodiversity to highly similar relict assemblages and ultimately causing amplified biodiversity loss at regional and global scales.     

Upward range extension of Andean anurans and chytridiomycosis to extreme elevations in response to tropical deglaciation

High-alpine life forms and ecosystems exist at the limits of habitable environments, and thus, are especially sensitive to environmental change. Here we report a recent increase in the elevational limit of anurans following glacial retreat in the tropical Peruvian Andes. Three species have colonized ponds in recently deglaciated terrain at new record elevations for amphibians worldwide (5244–5400 m). Two of these species were also found to be infected with Batrachochytrium dendrobatidis ( Bd ), an emerging fungal pathogen causally associated with global amphibian declines, including the disappearance of several Latin American species. The presence of this pathogen was associated with elevated mortality rates of at least one species. These results represent the first evidence of upward expansion of anurans to newly available habitat brought about by recent deglaciation. Furthermore, the large increase in the upper limit of known Bd infections, previously reported as 4112 m in Ecuador, to 5348 m in this study, also expands the spatial domain of potential Bd pathogenicity to encompass virtually all high elevation anuran habitats in the tropical Andes.     

江西赣江源区域两栖动物的群落组成和物种多样性特征

赣江发源于武夷山脉南段西麓的高山岭间,该区域独特的地理环境和气候特征蕴育了丰富的生物多样性。然而关于该区域两栖动物群落组成和物种多样性调查非常匮乏,不利于赣江源头两栖动物物种多样性的保护。于2016年4-9月期间在江西赣江源区域采用样线法调查了两栖动物的资源状况、群落组成及物种多样性特征,比较了它们在山地森林区、丘陵森林与农田区和盆地农田区3类栖息地之间的差异性。结果表明：赣江源区域分布有8科23种两栖动物,新增记录3个物种,包括尖舌浮蛙、寒露林蛙和九龙棘蛙,泽陆蛙和饰纹姬蛙为优势种。赣江源区域的两栖动物群落组成和物种多样性存在显著的季节间差异和栖息地间差异;两栖动物季节性繁殖是造成前者差异的主要因素,而土地利用类型、栖息地特征、空间距离、生活习性的物种特性等因素成就了后者差异的出现。因此,春、夏季一般有比秋季见到更高的两栖动物物种丰富度和多样性;山地森林区的两栖动物物种丰富度和多样性最高,盆地农田区次之,丘陵森林与农田区的最低。山地森林区应成为赣江源区域两栖动物多样性保护的优先区域。国家Ⅱ级重点保护野生动物虎纹蛙,在3类栖息地中均有分布,且在盆地农田区和山地森林区能见到更多个体,但农田区分布的虎纹蛙遭受到更大的威胁,建议加强对农田区虎纹蛙及其栖息地的保护。     

The life span of red blood cells in the amphibian larvae, Rana catesbeiana

Nearly one hundred amphibian tadpoles were made anemic by phenylhydrazine injection. During the recovery period radioactive thymidine was incorporated into the DNA of the nucleated amphibian red blood cells. Over the next 135 days blood was drawn and smears of circulating red blood cells were prepared. The blood smears from each tadpole were autoradiographed and percentage of labeled nuclei (PLN) determined. The average life span of tadpole red blood cells was calculated from the change in PLN, and is about 100 days. It is concluded that during the transition from tadpole to frog, the tadpole red blood cell life span must be drastically shortened to account for the hemoglobin transition observed during amphibian metamorphosis.     

Dermatan sulfate is the major metachromatic glycosaminoglycan in the integument of the anuran Bufo ictericus

Glycosaminoglycans from the ventral and dorsal integuments of the anuran Bufo ictericus were characterized based on biochemical and histochemical methods. Dermatan sulfate is the major metachromatic glycosaminoglycan found in these tissues, but small amount of heparan sulfate was also detected. The average molecular mass of the dermatan sulfate is approximately 20 kDa, similar to the glycosaminoglycan isolated from mammalian skin. In addition, the amphibian integument contains high amounts of hyaluronic acid, especially in the ventral area. We also observed that the glycosaminoglycans occur in the anuran integument as irregular deposits through the spongious dermis and in the mast cells, as revealed by histochemical analysis using Alcian blue, dimethylmethylene blue and toluidine blue stains. The concentration and composition of glycosaminoglycans found in the amphibian integument resemble those from mammalian skin except for the higher concentration of hyaluronic acid in the amphibian tissue. Possibly, this observation indicates that the function of the sulfated glycosaminoglycan in these tissues has been preserved during evolution, although the amphibian integument and the human skin have their own particular physiology.     

Effect of chloride withdrawal on the geometry of the T-tubules in amphibian and mammalian muscle

Summary The relative chloride permeabilities of the T-tubule membranes in mammalian (rat sternomastoid) and amphibian (toad sartorius) skeletal muscle fibers have been assessed from the change in volume of the T-tubules during chloride withdrawal from fibers exposed to low extracellular chloride concentrations. A 3.5- to 4.2-fold increase in T-tubule volume was found in mammalian fibers, and this was shown to be independent of the composition of the low chloride solution or the nature of the fixative used in preparation for electron microscopy. The increase in T-tubule volume was transient and was inhibited by factors which block chloride conductance, i.e., low pH, 2,4-dichlorophenoxyacetic acid, and nitrate ions. A small increase (1.48-fold) in T-tubule volume was seen in amphibian fibers when chloride ions were replaced by sulphate ions. No increase in volume was observed in amphibian T-tubules when methyl sulphate ions replaced chloride ions. The results support the idea that the chloride permeability of the T-tubule membrane is significantly higher in mammalian fibers than in amphibian fibers.     

Amphibian diversity in Polish cities: Taxonomic diversity,functional diversity and evolutionary distinctiveness

As a process affecting animal communities, urbanization has been the subject of numerous studies. However, amphibians are still among the least studied vertebrate groups in urbanized landscapes. Generally, it has been found that the process of loss of amphibian diversity is nonrandom, with species from older evolutionary lines at greater risk. Regional data on amphibian assemblages in urban areas is a very useful tool for assessing how these assemblages react to changes.The aim of the present paper is to assess the diversity of amphibians in Polish cities based on data in the relevant literature, exploring different metrics (e.g., taxonomic, functional, and evolutionary diversity) calculated in amphibian species assemblages. We used data from 18 articles (including grey literature), characterized by comparable research methods and published between 1999 and 2017.Overall, amphibian species richness (ASR) amounted to an average of 9 species, ranging from 5 to 11 species per city. The higher species richness occurred in Białystok in North-west of Poland. Functional evenness (FEve), evolutionary distinctiveness (ED sum), and functional richness (FRic) were strongly positively correlated with ASR. However, ED mean was not significantly correlated with the total number of species in the community. Three taxa, the hybridogenetic water frogs Pelophylax esculentus complex, the common toad Bufo bufo, and the common frog Rana temporaria, occurred in all analyzed amphibian assemblages. Our study is one of the first attempts to compare urban amphibian assemblages, using different and complementary diversity metrics on a large spatial scale. In conclusion, we highlight that urban areas play an important role for conservation of amphibians, because they support amphibian assemblages characterized by a high level of overall diversity.     

Amphibian molecular ecology and how it has informed conservation

Molecular ecology has become one of the key tools in the modern conservationist's kit. Here we review three areas where molecular ecology has been applied to amphibian conservation: genes on landscapes, within‐population processes, and genes that matter. We summarize relevant analytical methods, recent important studies from the amphibian literature, and conservation implications for each section. Finally, we include five in‐depth examples of how molecular ecology has been successfully applied to specific amphibian systems.     

湖南壶瓶山国家级自然保护区两栖 爬行动物多样性的时空格局

本研究利用2013至2016年湖南壶瓶山国家级自然保护区巡护监测数据,评估壶瓶山保护区两栖爬行动物多样性水平。壶瓶山保护区在8个监测站点布设了25条两栖爬行动物调查样线,进行常规监测,其中,日间样线14条,夜间样线11条,日间样线平均长度4 km,夜间样线平均长度0.75 km。每个月,每条样线平均调查3次。4年共调查到62种两栖爬行动物,占湖南省两栖爬行动物总种数的38.04%。逐月计算各监测站点的alpha多样性指数和整个保护区的beta多样性指数,按季节比较不同站点间物种组成的Hellinger距离。结果显示,保护区不同位置间、不同的监测站点间以及年际间的两栖爬行动物多样性没有显著差异,提示保护区环境具有相对稳定性。但是,个别位于实验区或邻近实验区的站点,物种组成有着剧烈的波动,表明人为活动影响了两栖爬行动物的分布。另外,保护区两栖爬行动物的物种组成与多样性有着显著的季节差异,这与两栖爬行动物的生物学特性有关。以上结果说明,壶瓶山保护区两栖爬行动物的多样性结构具有稳定性和敏感性的特点,可以考虑用作保护区生物多样性水平的监测指标。     

江西桃红岭梅花鹿国家级自然保护区两栖动物资源调查

江西桃红岭梅花鹿国家级自然保护区自成立以来,一直未进行过两栖动物资源调查。为掌握两栖动物本底资源现状,评价当地的生物多样性,作者于2005年4月下旬至5月上旬、8月中旬、2006年7月下旬,前后3次对该保护区两栖动物资源进行了实地调查。保护区现已记录两栖动物19种,隶属2目7科,占江西省39种两栖动物的48.72%。其中以16种东洋界物种为主,广布种3种,无古北界物种。东洋界物种包括10种华中区与华南区共有种及6种华中区物种。这种动物区系组成特点与保护区在动物地理区划上属东洋界华中区东部丘陵平原亚区一致。此次考察增加赣北(鄱阳湖)平原省两栖动物新纪录6种,分别是中国雨蛙(Hyla chinensis)、弹琴蛙(Hylarana adenopleura)、阔褶水蛙(H.latouchii)、花臭蛙(Odorrana schmackeri)、斑腿树蛙(Rhacophorus megacephalus)和小弧斑姬蛙(Microhyla heymonsi)。最后,结合调查结果对保护区内两栖动物的分布和资源现状进行了分析。     

A novel myotropic peptide from the skin secretions of the tree frog, Polypedates pingbianensis

A novel myotropic peptide, polypedatein, was purified and characterized from the skin secretions of the tree frog, Polypedates pingbianensis. Its primary structure, TLLCKYFAIC, was determined by Edman degradation and mass spectrometry. Polypedatein was subjected to bioassays including myotropic, antimicrobial, and serine protease inhibitory activities, which are related with many amphibian skin bioactive peptides. It was found to elicit concentration-dependent contractile effects on isolated rat ileum. cDNA clones encoding the precursor of polypedatein were isolated by screening a skin cDNA library of P. pingbianensis and then sequenced. The amino acid sequence deduced from the cDNA sequences matches well with the result from Edman degradation. BLAST search revealed that the sequence of polypedatein did not show similarity to known protein or peptide sequences. Especially, polypedatein does not contain conserved structural motifs of other amphibian myotropic peptides, such as bradykinins, bombesins, cholecystokinin (CCK), and tachykinins, indicating that polypedatein belongs to a novel amphibian myotropic peptide family. The signal peptide of the precursor encoding polypedatein shows significant sequence identity to that of other amphibian skin defensive peptides, such as antimicrobial peptides, bradykinins, lectins, and serine protease inhibitors, suggesting that polypedatein belongs to a novel amphibian myotropic peptide family. Polypedatein is also the first bioactive peptide from the genus of the frog, Polypedates.     

Crystallins in the differentiation and regeneration processes of the crystalline lens in amphibia

The published and authors' data have been summarized on (1) the spectrum and properties of crystallins in different amphibian species, (2) localization and synthesis of crystallins in different cellular compartments of the adult amphibian lens, (3) dynamics of crystallin formation during embryogenesis and (4) lens regeneration from tissues of the larval and adult amphibian eyes. The necessity of more detailed studies of crystallin synthesis during embryogenesis and lens regeneration using molecular biological and biochemical methods is stressed. The significance of this approach is illustrated by the pioneering data of Soviet scientists on crystallin polypeptides and corresponding mRNAs in development of Rana temporaria obtained with the use of DNA-RNA hybridization and immunoelectroblotting.     

江西省两栖类动物多样性与地理区划

本研究整合近年来江西省两栖类动物物种分布新纪录,对江西省两栖类动物多样性进行编目整理。结果表明,近年来江西省新增23种两栖类物种分布新纪录,两栖类动物累计达2目8科58种,包括2种国家Ⅱ级重点保护物种和40种中国特有种。江西省两栖动物区系组成以东洋界华中区和华南区共有种为主,无古北界种类。东洋界种类54种,占总种数的93.1%,广布种4种,占总种数的6.9%。生态类型以流水型最多,陆栖-静水型次之。对13个保护地两栖类动物物种组成的聚类分析将其分为4个聚类群：赣北、赣东北、赣南、赣西。聚类结果在一定程度上支持早期江西省两栖动物地理区划,我们建议将罗霄山脉划为单独的赣西（罗霄）山地省。