53 resultados para Slimy salamander


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Ambystoma mabeei, a small relatively uncommon salamander of the sub-genus Linguaelapsus, is limited in distribution to the coastal plain of North and South Carolina. First described in 1928, few specimens have been collected and details of its biology have remained essentially unknown. (PDF contains 3 pages)

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Water-soluble skin secretions of salamander Tylototriton venucosus, first described by Anderson in 1871, were studied for their biological and enzymatic activities. They were found to be toxic to mice with an intraperitoneal LD50 of 11.5 mg/kg. Using Sephadex G-75 gel filtration, it was proven that the toxic components of the secretions are proteins with molecular weights ranging from 30,000 to 50,000 Da. The secretions of T. venucosus display a wide spectrum of antimicrobial activities and also contain both proteolytic activity and trypsin inhibitory activity. In contrast, neither hemolytic nor hemorrhagic activities were found. The secretions were determined to have phospholipase A(2) activity; however, no acetylcholine esterase activity was detectable under the assay conditions.

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Two ciliated protozoa, Balantidium sinensis Nie 1935 and Balantidium andianusi n. sp., were isolated from the feces of a wild Chinese giant salamander (Andrias davidianus) captured from the mountainous area of Shiyan, Hubei Province, Central China in October 2006. It is the first report of Balantidium species inhabiting Cryptobranchoidea amphibians. The occurrence of B. sinensis in A. davidianus should be a new record because the type specimens were first discovered and named by Nie in 1935 from Rana nigromaculata and Rana plancyi. For the lack of enough descriptions of taxonomic features in the previous report, it was re-described in detail and compared with Nie's type specimens and B. giganteum to complete the morphological descriptions in the present work. B. andianusi n. sp. was considered to be a new species based on its unique morphological characteristics, especially the high length/width ratio of the vestibulum (8:1). Comparisons were also made among Balantidium species that were found from urodele amphibians.

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We predicted that the probability of egg occurrence of salamander Salamandrina perspicillata depended on stream features and predation by native crayfish Austropotamobius fulcisianus and the introduced trout Salmo trutta. We assessed the presence of S. perspicillata at 54 sites within a natural reserve of southern Tuscany, Italy. Generalized linear models with binomial errors were constructed using egg presence/absence and altitude, stream mean size and slope, electrical conductivity, water pH and temperature, and a predation factor, defined according to the presence/absence of crayfish and trout. Some competing models also included an autocovariate term, which estimated how much the response variable at any one sampling point reflected response values at surrounding points. The resulting models were compared using Akaike's information criterion. Model selection led to a subset of 14 models with Delta AIC(c) <7 (i.e., models ranging from substantial support to considerably less support), and all but one of these included an effect of predation. Models with the autocovariate term had considerably more support than those without the term. According to multimodel inference, the presence of trout and crayfish reduced the probability of egg occurrence from a mean level of 0.90 (SE limits: 0.98-0.55) to 0.12 (SE limits: 0.34-0.04). The presence of crayfish alone had no detectable effects (SE limits: 0.86-0.39). The results suggest that introduced trout have a detrimental effect on the reproductive output of S. perspicillata and confirm the fundamental importance of distinguishing the roles of endogenous and exogenous forces that act on population distribution.

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Dissertação de mest., Biologia Marinha, Faculdade de Ciências do Mar e do Ambiente, Universidade do Algarve, 2008

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The Sardinian brook salamander, Euproctus platycephalus, is a cryptically coloured urodele found in streams, springs and pools in the main mountain systems of Sardinia, and is classified as critically endangered by IUCN. General reviews of the mountainous range where salamanders occur are numerous, but very few field-based distribution studies exist on this endemic species. Through a field and questionnaire survey, conducted between 1999 and 2001, we report a first attempt to increase data on the present distribution of E. platycephalus. A total of 14 localities where Sardinian salamanders are represented by apparently stable and in some cases abundant populations have been identified, as well as 30 sites where species presence has been recorded after 1991. Some 11 historical sites were identified which are no longer inhabited by the species. The implications of this distributional study for the conservation of the species and for the realization of an updated atlas are discussed.

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Standard metabolic rate (SMR) and maximal metabolic rate (MMR) are fundamental measures in ecology and evolution because they set the scope within which animals can perform activities that directly affect fitness. In ectotherms, both SMR and MMR are repeatable over time when measured at a single ambient temperature (Ta). Many ectotherms encounter variable Ta from day to day and over their lifetime, yet it is currently unknown whether individual differences hold across an ecologically relevant range of Ta (i.e. thermal repeatability; RT). Moreover, it is possible that thermal sensitivity of SMR and MMR are important individual attributes, and correlated with one another, but virtually nothing is known about this at present. We measured SMR and MMR across an ecologically relevant Ta gradient (i.e. from 10 to 25 °C) in wild-caught salamanders (Plethodon albagula) and found that RT was significant in both traits. SMR and MMR were also positively correlated, resulting in a lower RT in absolute and factorial aerobic scopes (AAS and FAS). We found significant individual differences in thermal sensitivity for both SMR and MMR, but not for AAS and FAS. The intercept (at Ta = 0 °C) and the slope of the thermal reaction norms were negatively correlated; individuals with low MR at low Ta had a higher thermal sensitivity. Finally, individuals with a high thermal sensitivity for SMR also had high thermal sensitivity for MMR. Our results suggest that natural selection occurring over variable Ta may efficiently target the overall level of - and thermal sensitivity in - SMR and MMR. However, this may not be the case for metabolic scopes, as the positive correlation between SMR and MMR, in addition to their combined changes in response to Ta, yielded little individual variation in AAS and FAS. Our results support the idea that organisms with low metabolism at low Ta have a high metabolic thermal sensitivity as a compensatory mechanism to benefit in periods of warmer environmental conditions. Hence, our study reveals the importance of considering within-individual variation in metabolism, as it may represent additional sources of adaptive (co)variation.

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Morphological and genetic data for the Iberian golden- striped salamander, Chioglossa lusitanica, demonstrate the existence of two groups with southern and northern ranges, connected by a zone of intergradation in central Portugal. Because reproductive isolation between them is incomplete we consider the groups to be subspecies. The type locality of C. lusitanica ( Bucaco near Lousa) is situated inside the mixed zone. This necessitates identification of the nominotypical subspecies. We sequenced a fragment of mitochondrial DNA from one of the species' syntypes and we determined what position over a latitudinal transect maximizes the morphological discrimination between the groups. Both approaches indicate that C. lusitanica from Bucaco represents the southern subspecies. A new subspecies of C. lusitanica is described from a northern locality ( Valongo near Porto in northwestern Portugal). A lectotype is designated for Chioglossa lusitanica.

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The golden-striped salamander (Chioglossa lusitanica) is an endemic species inhabiting stream-side habitats in mountainous areas in the northwestern Iberian Peninsula. This salamandrid is listed in the IUCN Red Data Book as a threatened species. The combination of bioclimatic modeling of the species distribution and multivariate analysis of genetic and phenotypic data strengthens previous hypotheses concerning the historical biogeography of C. lusitanica: the Pleistocene subdivision of the species' range and a process of postglacial recolonization. Discrepancies between bioclimatic modeling predictions and the present-day distribution suggest that the species may still be expanding its range northwards. We propose the identification of two distinct units for the conservation of the species and suggest that this information should be taken into account in defining key areas for conservation in the Iberian Peninsula.

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Morphometric and colour pattern variation in the endemic Iberian salamander Chioglosso lusitanica is concordant with the genetic differentiation of two groups of populations separated by the Mondego river ill Portugal. Salamanders from the south have shorter digits than those from the north. Clinal variation with a south to north increase in limb. toe and finger length was found superiniposed on this dichotomy resulting in stepped clines for characters describing appendage size. Genetic variability was paralleled by colour pattern variability in the contact zone and in northern populations. To explain the observed parallels we invoke the neutral processes of vicariant isolation. admixture in a secondary contact zone, genetic drift in addition to selection acting along all environmental gradient. Morphological constraints imposed by a highly specialized ecological niche may explain why the genetic subdivision of C. lusitanica since the early, Pleistocene has remained fairly cryptic.

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We developed 15 new polymorphic microsatellites for the plethodontid salamander Ensatina eschscholtzii. Loci were isolated from a genomic library from Ensatina eschscholtzii xanthoptica enriched for (AAAG)(n) repetitive elements. The number of alleles per locus ranged from 4 to 20 (mean 9) in the sampled population. Observed heterozygosity ranged from 0.37 to 1. None of the loci deviated from Hardy-Weinberg equilibrium or showed significant linkage disequilibrium after a Bonferroni correction for multiple comparisons. All loci amplified in the six other subspecies of the Ensatina eschscholtzii complex. These new markers will prove useful in measuring gene flow and population structure as well as patterns of mating and sperm use in Ensatina.

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Previous analyses of mitochondrial (mt)DNA and allozymes covering the range of the Iberian endemic golden-striped salamander, Chioglossa lusitanica, suggested a Pleistocene split of the historical species distribution into two population units (north and south of the Mondego river), postglacial expansion into the northernmost extant range, and secondary contact with neutral diffusion of genes close to the Mondego river. We extended analysis of molecular variation over the species range using seven microsatellite loci and the nuclear P-fibrinogen intron 7 (beta-fibint7). Both microsatellites and beta-fibint7 showed moderate to high levels of population structure, concordant with patterns detected with mtDNA and allozymes; and a general pattern of isolation-by-distance, contrasting the marked differentiation of two population groups suggested by mtDNA and allozymes. Bayesian multilocus analyses showed contrasting results as populations north and south of the Douro river were clearly differentiated based on microsatellites, whereas allozymes revealed differentiation north and south of the Mondego river. Additionally, decreased microsatellite variability in the north supported the hypothesis of postglacial colonization of this region. The well-documented evolutionary history of C. lusitanica, provides an excellent framework within which the advantages and limitations of different classes of markers can be evaluated in defining patterns of population substructure and inferring evolutionary processes across distinct spatio-temporal scales. The present study serves as a cautionary note for investigations that rely on a single type of molecular marker, especially when the organism under study exhibits a widespread distribution and complex natural history. (C) 2008 The Linnean Society of London, Biological Journal of the Linnean Society, 2008, 95, 371-387.

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Fifty-one slimy sea plumes (Pseudopterogorgia americana Gmelin, 1791) were sampled for caridean shrimps at Guana Island, British Virgin Islands, during one week in July 1992. Sam- pling depth ranged from 3-22 m. Nine species were collected: Hippolyte nicholsoni Chace, 1972; Latreutes sp.; Neopontonides chacei Heard, 1986; Perclimenes cf. patae Heard and Spotte, 1991; Periclimenes cf. pauper Holthuis, 1951; Periclimenes sp.; Pseudocoutierea antillensis Chace, 1972; Tozeuma cf. cornutum Milne Edwards, 1881; and Trachycaris rugosa (Bate, 1888). A total of 1,418 specimens (including fragments) was obtained. The number of shrimp species per gorgonian ranged from 1-5; one gorgonian harbored 156 shrimps. The two predominant species, N. chacei and H. nicholsoni, occupy different mean depths (12.6 and 8.2 m, respectively). Sexual dimorphism assessed with Mann-Whitney U-tests was not apparent in the specimens of N. chacei (P > 0.05), but females of H. nicholsoni were significantly larger than males (P < 0.001). Minimum carapace length (CL, the tip of the rostrum to the posterior dorsal margin of the carapace) at which male N. chacei acquire a single appendix masculina spine is 1.25 mm; male H. nicholsoni can acquire a single spine at 0.9 mm CL. Histological sections of male N. chacei showed that shrimp with 0 or 1 spine are least likely to be mature. Female N. chacei can become ovigerous at 1.9 mm CL and female H. nicholsoni at 1.2 mm CL. The taxonomic status of 5 of the 9 species collected is uncertain.

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Background Understanding the demographic processes underlying population dynamics is a central theme in ecology. Populations decline if losses from the population (i.e., mortality and emigration) exceed gains (i.e., recruitment and immigration). Amphibians are thought to exhibit little movement even though local populations often fluctuate dramatically and are likely to go exinct if there is no rescue effect through immigration from nearby populations. Terrestrial salamanders are generally portrayed as amphibians with low migratory activity. Our study uses demographic analysis as a key to unravel whether emigration or mortality is the main cause of "losses" from the population. In particular, we use the analysis to challenge the common belief that terrestrial salamanders show low migratory activity. Results The mark-recapture analysis of adult salamanders showed that monthly survival was high (> 90%) without a seasonal pattern. These estimates, however, translate into rather low rates of local annual survival of only ~40% and suggest that emigration was important. The estimated probability of emigration was 49%. Conclusion Our analysis shows that terrestrial salamanders exhibit more migratory activity than commonly thought. This may be due either because the spatial extent of salamander populations is underestimated or because there is a substantial exchange of individuals between populations. Our current results are in line with several other studies that suggest high migratory activity in amphibians. In particular, many amphibian populations may be characterized by high proportions of transients and/or floaters.