First Documentation of Cultural Transmission of Predator Recognition by Larval Amphibians

Predation is a pervasive selective agent shaping a prey's behaviour, morphology and life history. To survive, prey animals have to respond adaptively to predation threats and this can be achieved through learned predator recognition. Cultural transmission of predator recognition is likely a widespread means of learning in social animals, including mammals, birds and fishes. However, no studies have investigated the cultural transmission of predator recognition in amphibians. In our study, we examined whether naïve woodfrog (Rana sylvatica) tadpoles can acquire the recognition of the odour of a predatory tiger salamander (Ambystoma tigrinum) from experienced conspecifics. After conditioning some tutors to recognize salamander odour, we paired naïve observer tadpoles with either a salamander‐naïve or salamander‐experienced tutor and exposed the pairs to either salamander odour or a water control. Observers were subsequently tested alone for a response to salamander odour. We found that when given salamander odour, observer tadpoles that were paired with a salamander‐experienced tutor successfully learned to recognize the salamander odour as a threat, whereas the observers paired with salamander‐naïve tutors did not. Likewise, tadpoles exposed to the water control did not learn to recognize the salamander regardless of whether they were paired with a naïve or experienced tutor. This is the first study demonstrating cultural transmission of predator recognition in an amphibian species.     

Climate change and range restriction of common salamanders in eastern Canada and the United States

The sensitivity of amphibian species to shifts in environmental conditions has been exhibited through long-term population studies and the projection of ecological niche models under expected conditions. Species in biodiversity hotspots have been the focus of ample predictive modeling studies, while, despite their significant ecological value, wide-ranging and common taxa have received less attention. We focused on predicting range restriction of the spotted salamander (Ambystoma maculatum), blue-spotted salamander (A. laterale), four-toed salamander (Hemidactylium scutatum), and red-backed salamander (Plethodon cinereus) under future climate scenarios. Using bias-corrected future climate data and biodiversity database records, we developed maximum entropy (MaxEnt) models under current conditions and for climate change projections in 2050 and 2070. We calculated positivity rates of species localities to represent proportions of habitat expected to remain climatically suitable with continued climate change. Models projected under future conditions predicted average positivity rates of 91% (89–93%) for the blue-spotted salamander, 23% (2–41%) for the spotted salamander, 4% (0.7–9%) for the four-toed salamander, and 61% (42–76%) for the red-backed salamander. Range restriction increased with time and greenhouse gas concentration for the spotted salamander, four-toed salamander, and red-backed salamander. Common, widespread taxa that often receive less conservation resources than other species are at risk of experiencing significant losses to their climatic ranges as climate change continues. Efforts to maintain populations of species should be focused on regions expected to experience fewer climatic shifts such as the interior and northern zones of species' distributions.     

患病大鲵中弗氏柠檬酸杆菌的分离与鉴定

【目的】确定导致大鲵(Andrias davidianus)细菌性感染死亡的病原。【方法】从大鲵肝脏中分离细菌,通过Biolog微生物自动鉴定系统及分子生物学方法对纯培养的细菌进行鉴定,再用大鲵和鲫鱼分别进行人工感染试验,以确定分离菌的致病性,同时对分离到的病原菌进行药物敏感试验。【结果】从患病大鲵肝脏中分离到一株致病菌JZ01,经人工感染健康大鲵,可复制与自然发病相同的症状,且从人工感染病鲵体内再次分离到相同的病原菌。该致病菌对健康鲫鱼也有致病性。经Biolog微生物自动鉴定系统的鉴定,以及进一步的16S rDNA基因序列和系统发育分析都表明,此致病菌为弗氏柠檬酸杆菌。药物敏感性试验表明,该菌株对氨曲南、头孢三嗪、先锋噻肟等9种药物高度敏感。【结论】弗氏柠檬酸杆菌是大鲵的一种致病菌。本文在国内外首次报道了该菌对大鲵具有致病性。     

大鲵保护生物学及其研究进展

大鲵（Andrias davidianus)为我国特有的珍稀两栖动物,已列入国家二级保护动物名录,并列入CITES公约附录Ⅰ中。自20世纪50年代起,由于过度收购、非法捕杀和栖息地丧失等原因,大鲵种群数量下降极为严重,湖南、安徽等地的大鲵产量在20世纪50年代至70年代下降超过80％,分布区也极度萎缩,形成了12块岛屿状区域,目前分布于以我国中部山区的长江流域为主的17个省区。部分已建立的大鲵保护区经费短缺,人员不足,管理不力,状况不容乐观。非法捕捉和栖息地丧失仍是威胁大鲵生存的主要因素,保护管理力度还需进一步加强。     

An experimental study on the effects of salamander larvae on isopods in stream pools

SUMMARY 1. We used a combination of field surveys and field and laboratory experiments to examine the effects of predatory small-mouthed salamander larvae, Ambystoma barbouri (Kraus and Petranka), on the density and microhabitat use of benthic isopods, Lirceus fontinalis (Rafinesque).
2. A survey of four field stations yielded a significant negative relationship between the densities of salamander larvae and isopods.
3. A field experimental manipulation of salamander density confirmed that salamanders reduce isopod density and isopod use of open micro-habitat. Salamanders did not significantly affect the mean or coefficient of variation in isopod size.
4. A laboratory experiment showed that in the absence of refuges for isopods, salamanders were capable of eating large numbers of isopods; small isopods were particularly vulnerable to salamander predation.     

Detection of Batrachochytrium dendrobatidis in Endemic Salamander Species from Central Texas

A nested PCR protocol was used to analyze five endemic salamander species from Central Texas for the presence of the emerging pathogen, chytrid fungus (Batrachochytrium dendrobatidis). Chytrid fungus was detected from samples of each of the five species sampled: with low abundance, in the Texas salamander (Eurycea neotenes) (1 positive out of 16 individuals tested; 1/16), the Blanco River Springs salamander (E. pterophila) (1/20), the threatened San Marcos salamander (E. nana) (1/17), and the endangered Barton Springs salamander (E. sosorum) (1/7); much higher abundance was obtained for the Jollyville Plateau salamander (E. tonkawae) (6/14), which has recently been petitioned for addition to the USA endangered species list. With one exception, sequences of PCR products were identical to the 5.8S rRNA gene, and nearly so for the flanking internal transcribed spacer (ITS) regions of B. dendrobatidis which confirmed the detection of chytrid fungus, and thus demonstrated the presence of this pathogen in populations of endangered species in Central Texas. These confirmations were obtained from nonconsumptive tail clippings which confirms the applicability of historically collected samples from other studies in the examination of the fungus across time.     

中国大鲵研究概况

中国大鲵(Andrias davidianus)为我国特有物种,也是国家二类保护水生野生动物.野生大鲵多栖息在山区溪流里,喜穴居,怕光怕声,以鱼蟹等水生动物为食,从数量上看,以陕西秦岭山区居多.大鲵经济价值极高,在美食、保健、医药、观赏等方面均具有广泛开发利用的前景,因而颇受社会各界关注.近年来对大鲵的科学研究涉及多个...     

A Test of Local Enhancement in Amphibians

Local enhancement is an underexplored social learning mechanism that is often observed in organisms that live in groups. This mechanism occurs when individuals are attracted to areas where conspecifics have previously been, but which are not present when the animal actually moves into the area. We tested for local enhancement in wood frog tadpoles (Lithobates sylvatica) and spotted salamander larvae (Ambystoma maculatum) in three experiments that exposed individuals to one side of a test chamber which was empty and another that contained a group of three conspecifics. Side preference of the focal individual was recorded once the conspecifics were removed. Tadpoles showed a clear preference for moving to areas where a group of tadpoles had previously been located. Conversely, this preference was not observed in salamander larvae. In addition, salamander larvae took significantly more time to initially choose a side. These results indicate that tadpoles exhibit local enhancement, whereas aquatic salamander larvae do not. This difference in social learning could be largely due to differences in aquatic ecology between tadpoles and salamander larvae.     

Zur Evolution der Embryonal- bzw. Larvalentwicklung bei Salamandra1

In the genus Salamandra occur mainly two kinds of propagation. The european spotted salamander (Salamandra salamandra) is ovoviviparous and lays a great number of larvas into the water, whereas the alpine salamander (Salamandra atra) gives birth to completely transformed gilless young ones. There are, however, several races of spotted salamander which are also viviparous. The development of such a variety, Salamandra salamandra bernardezi, is described and compared with the generation of the alpine salamander. The emancipation of the development of the larvas from their life in the water has certainly happened in several cases independent of each other under various oecological circumstances. Besides a race of spotted salamander was said to exist in a mountain lake in central Spain at about 6000 ft. This assertion proved to be wrong. The development of the embryo and the larva takes place in exactly the same way as with our native species. The results of the experiments of Mr. Kammerer are dicussed on the basis of the facts at our disposal.     

Determining threatened species distributions in the face of limited data: Spatial conservation prioritization for the Chinese giant salamander (Andrias davidianus)

The purpose of this study was to determine whether limited occurrence data for highly threatened species can provide useful spatial information to inform conservation. The study was conducted across central and southern China. We developed a habitat suitability model for the Critically Endangered Chinese giant salamander (Andrias davidianus) based on one biotic and three abiotic parameters from single‐site locality records, which represent the only relevant environmental data available for this species. We then validated model quality by testing whether increased percentage of predicted suitable habitat at the county level correlated with independent data on giant salamander presence. We randomly selected 48 counties containing historical records which were distinct from, and independent of, the single‐site records used to develop the model, and 47 additional counties containing >50% predicted suitable habitat. We interviewed 2,812 respondents near potential giant salamander habitat across these counties and tested for differences in respondent giant salamander reports between counties selected using each method. Our model predicts that suitable giant salamander habitat is found widely across central and southern China, with counties containing ≥50% predicted suitable habitat distributed in 13 provinces. Counties with historical records contain significantly more predicted suitable habitat than counties without historical records. There are no statistical differences in any patterns of respondent giant salamander reports in surveyed counties selected from our model compared with the areas of known historical giant salamander distribution. A Chinese giant salamander habitat suitability model with strong predictive power can be derived from the restricted range of environmental variables associated with limited available presence‐only occurrence records, constituting a cost‐effective strategy to guide spatial allocation of conservation planning. Few reported sightings were recent, however, with most being over 20 years old, so that identification of areas of suitable habitat does not necessarily indicate continued survival of the species at these locations.     

Genetic diversity of Chinese giant salamander (Andrias davidianus) based on the novel microsatellite markers

Chinese giant salamander (Andrias davidianus) is a rare amphibian species in the world. Microsatellite markers are a promising tool for accurate estimation population structure and genetic diversity. In this paper, we isolated novel microsatellite marker for Chinese giant salamander using fast isolation by AFLP of sequences containing repeats (FIASCO) method. More than 50% sequences in 132 clones had repeat number over ten times with di or trinucleeotide repeat except of (GA)₁₂. Seventy pairs of primers were designed and eleven polymorphic microsatellite loci were characterized for wild and cultivated Chinese giant salamander populations. The allele number was from 3 to 9 in different loci. Polymorphism information content was from 0.544 to 0.702 in cultivated population. The results implied more alleles and PIC were in the wild population than cultivated population. The observed heterozygosities in two populations were higher than 0.553. The data analysis suggested that the cultivated population has lower genetic diversity than wild population, which it??s perhaps owing to inbreeding in artificial breeding. To our knowledge, it??s the first time to isolated microsatellite markers for Chinese giant salamander. The result indicated that the markers were suitable for the population genetic analysis of Chinese giant salamander.     

Helminth and leech community structure in tadpoles and caudatan larvae of two amphibian species from Western Nebraska

Currently no comparative studies exist on helminth and leech community structure among sympatric anuran tadpoles and salamander larvae. During June-August 2007-2009, we examined 50 bullfrog tadpoles, Rana catesbeiana , 50 barred tiger salamander larvae, Ambystoma mavortium , and 3 species of snails from Nevens Pond, Keith County, Nebraska for helminth and leech infections. The helminth and leech compound community of this larval amphibian assemblage consisted of at least 7 species, 4 in bullfrog tadpoles and 4 in barred tiger salamander larvae. Bullfrog tadpoles were infected with 2 species of nematodes ( Gyrinicola batrachiensis and Spiroxys sp.) and 2 types of metacercariae ( Telorchis sp. and echinostomatids), whereas barred tiger salamander larva were infected with 1 species of leech ( Placobdella picta ), 2 species of adult trematodes ( Telorchis corti and Halipegus sp.), and 1 species of an unidentified metacercaria. The component community of bullfrog tadpoles was dominated by helminths acquired through active penetration, or incidentally ingested through respiratory currents, or both, whereas the component community of larval salamanders was dominated by helminths acquired through ingestion of intermediate hosts (χ2 = 3,455.00, P < 0.00001). Differences in amphibian larval developmental time (2-3 yr for bullfrog tadpoles versus 2-5 mo for salamander larvae), the ephemeral nature of intermediate hosts in Nevens Pond, and the ability of bullfrog tadpole to eliminate echinostome infections had significant effects on mean helminth species richness among amphibian species and years (t = 12.31, P < 0.0001; t = 2.09, P = 0.04). Differences in herbivorous and carnivorous diet and time to metamorphosis among bullfrog tadpoles and barred tiger salamander larvae were important factors in structuring helminth communities among the larval stages of these 2 sympatric amphibian species, whereas size was important in structuring helminth and leech communities in larval salamanders, but not in bullfrog tadpoles.     

史氏鲟的生态习性及其保护性利用

史氏鲟是中国现存鲟鱼中最具经济价值的优质珍稀鱼类,集观赏、美食于一体,具有个体大、寿命长、幼鱼成活率高、生长速度快等特点,经驯化后能迅速生长,对环境有较强的适应性;通过对史氏鲟生态习性、饲料和加工的研究,探讨史氏鲟繁养及利用技术;在对史氏鲟进行保护性利用的前提下深入研究史氏鲟的养殖和加工,为其他鲟鱼的研发积累经验。     

Introduced invertebrates are important prey for a generalist predator

Concern over biological invasions has drawn increased attention to the impacts of introduced predators or competitors, but not to the importance of introduced prey. North American forests are rich in introduced invertebrates, including species that represent relatively novel taxonomic or trophic guilds and show biased distributions among forest types. We analysed the diets of red‐backed salamanders, Plethodon cinereus, from three upland and three lowland forests to determine whether introduced prey are important contributors to geographical or temporal variation in salamander food resources. We found several introduced species were volumetrically important salamander prey, and were responsible for resource differences between forest types and much of the seasonal fluctuation in food resources in both forest types. In lowland forests, rain had a stronger effect on salamander predation on non‐native earthworms than native taxa, creating more dynamic resource fluctuations in resource levels than was observed in upland forests where earthworms were absent. With one exception, predation on non‐native species was positively associated with predation on native species, suggesting non‐native prey have added to salamander resources rather than replaced salamander predation on native taxa. We hypothesize that the novel resource gradients created by non‐native prey introductions are contributing to patterns of geographical and temporal phenotypic variation among salamander populations.     

大鲵皮肤色素提取工艺及抗氧化研究

为优化大鲵皮肤黑色素的提取工艺条件,探讨大鲵皮肤黑色素组成成分及体外抗氧化活性,采用酶法和碱溶酸沉法提取大鲵皮肤黑色素,以氢氧化钠浓度、液料比、提取温度为影响色素提取率因素,优化黑色素提取工艺条件,用紫外-可见光谱仪、红外光谱仪和超高效液相质谱仪测定黑色素的光谱特性,测定其抗氧化性。结果表明:大鲵皮肤黑色素最佳提取工艺条件为氢氧化钠浓度1.5 mol/L、液料比1∶15、提取温度45℃,黑色素提取率达0.65%。大鲵皮肤黑色素的紫外最大吸收波长为214 nm,由真黑色素和脱黑色素两种色素组成,其对超氧阴离子自由基的清除率为30.51%,对羟基自由基的清除率为54.17%。大鲵皮肤黑色素具有一定的体外抗氧化能力。     

Salamander diversity alters stream macroinvertebrate community structure

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Evidence for emergence of an amphibian iridoviral disease because of human-enhanced spread

Our understanding of origins and spread of emerging infectious diseases has increased dramatically because of recent applications of phylogenetic theory. Iridoviruses are emerging pathogens that cause global amphibian epizootics, including tiger salamander (Ambystoma tigrinum) die-offs throughout western North America. To explain phylogeographical relationships and potential causes for emergence of western North American salamander iridovirus strains, we sequenced major capsid protein and DNA methyltransferase genes, as well as two noncoding regions from 18 geographically widespread isolates. Phylogenetic analyses of sequence data from the capsid protein gene showed shallow genetic divergence (< 1%) among salamander iridovirus strains and monophyly relative to available fish, reptile, and other amphibian iridovirus strains from the genus Ranavirus, suggesting a single introduction and radiation. Analysis of capsid protein sequences also provided support for a closer relationship of tiger salamander virus strains to those isolated from sport fish (e.g. rainbow trout) than other amphibian isolates. Despite monophyly based on capsid protein sequences, there was low genetic divergence among all strains (< 1.1%) based on a supergene analysis of the capsid protein and the two noncoding regions. These analyses also showed polyphyly of strains from Arizona and Colorado, suggesting recent spread. Nested clade analyses indicated both range expansion and long-distance colonization in clades containing virus strains isolated from bait salamanders and the Indiana University axolotl (Ambystoma mexicanum) colony. Human enhancement of viral movement is a mechanism consistent with these results. These findings suggest North American salamander ranaviruses cause emerging disease, as evidenced by apparent recent spread over a broad geographical area.     

Non-consumptive effects of larval Salamandra on crustacean prey: can eggs detect predators?

Predators affect prey populations not only by prey consumption but also in nonconsumptive ways including modifying prey behavior. I tested the effects of fire salamander larvae (Salamandra infraimmaculata) on populations of co-occurring crustacean species in artificial outdoor pools. I also tested whether these effects were due entirely to prey consumption by Salamandra larvae or alternatively to some nonconsumptive effect. The soil (containing crustacean eggs) added to the artificial pools was collected from a dried-out temporary pool that is inhabited by Salamandra during the early part of the hydroperiod. I randomly assigned the pools to one of three treatments: control, free Salamandra, or caged Salamandra. Free salamander larvae could roam the entire pool and prey upon crustaceans. Caged salamander larvae were placed within a cage with having 250-μm mesh windows. They could not prey upon the crustaceans but could, for example, influence them by chemical cues. Densities of the three dominant crustacean species (Arctodiaptomus similis, Ceriodaphnia quadrangula and Cyzicus sp.) were drastically reduced in both salamander treatments compared to the control. Crustacean densities, however, were not significantly different between the two salamander treatments. One plausible explanation is that crustacean eggs can detect the presence of this predator via chemical cues and delay hatching. Received: 4 March 1996 / Accepted, 23 October 1996     

黄山市大鲵资源古今及保护

本文记述了黄山市大鲵资源分布及其演变概况,大鲵资源枯竭的原因和对保护大鲵资源的建议。