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Dispersal is one of the main processes that determine community structure. Individuals make dispersal decisions according to environmental and/or social cues that reflect the fitness prospects in a given patch. The presence and abundance of heterospecifics within the same ecological guild, and/or their breeding success, may act as public information that influences movement decisions. To date, most studies investigating the role of heterospecific attraction have focused on habitat choice, using both experimental and correlational approaches. The present study is the first to examine how long-term variation in heterospecific density in breeding patches may affect dispersal patterns in spatially structured populations. We investigate how the dispersal decisions of the great crested newt (Triturus cristatus) are related to the variable density of two other newt species, the alpine newt (Ichthyosaura alpestris) and the palmate newt (Lissotriton helveticus). To examine this issue, we used capture-recapture data collected in an experimental pond network over a 20-year period. The results revealed that the great crested newt’s dispersal is context dependent and is affected by variation in heterospecific density: individuals were less likely to emigrate from ponds with high heterospecific density and were more likely to immigrate to ponds with high heterospecific density. These findings suggest that individuals adjust their dispersal decisions at least partly based on public information provided by heterospecifics. This mechanism may play a critical role in the dynamics of spatially structured populations and community functioning. [ABSTRACT FROM AUTHOR]

Genetic admixture between endangered native and non-native invasive species poses a complex conservation problem. Decision makers often need to quickly screen large numbers of individuals and distinguish natives from morphologically similar invading species and their genetically admixed offspring. We describe a protocol using the fast and economical Kompetitive Allele Specific PCR (KASP) technology for genotyping on a large scale. We apply this protocol to a case study of hybridization between a native and an invasive crested newt species. Using previously published data, we designed a panel of ten nuclear and one mitochondrial diagnostic SNP markers. We observed only minor differences between KASP and next-generation sequencing data previously produced with the Ion Torrent platform. We briefly discuss practical considerations for tackling the insidious conservation problem of genetic admixture between native and invasive species. The KASP genotyping protocol facilitates policy decision making for the crested newt case and is generally applicable to invasive hybridization with endangered taxa. [ABSTRACT FROM AUTHOR]

Predation imposes selection on the ability of prey to recognize and respond to potential threats. Many prey species detect predators via chemoreception, particularly in aquatic environments. Also, chemical cues from injured prey are often perceived as an indication of predation risk. However, because antipredatory behavior can be costly, prey responses should depend on the current level of risk that each predator poses, which may depend on the type of chemical cues detected. We exposed larval newts, Triturus pygmaeus, to chemical cues from predator larval beetles or to alarm cues from conspecific larval newts and examined the behavioral changes of larval newts. Results showed that larval newts reduced activity levels when conspecific alarm cues were present but not when the predator cues alone were present. These results might suggest that larval newts are unable to recognize predator chemicals. To avoid costs of unnecessary antipredatory behaviors, larval newts may benefit by avoiding only predators that represent a current high level of threat, showing only antipredatory responses when they detect conspecific alarm cues indicating that an actual predatory attack has occurred. [ABSTRACT FROM AUTHOR]

The ability to modify phenotypes in response to heterogeneity of the thermal environment represents an important component of an ectotherm's non-genetic adaptive capacity. Despite considerable attention being dedicated to the study of thermally-induced developmental plasticity, whether or not interspecific interactions shape the plastic response in both a predator and its prey remains unknown. We tested several predictions about the joint influence of predator/prey scents and thermal conditions on the plasticity of preferred body temperatures ( T) in both actors of this interaction, using a dragonfly nymphs-newt larvae system. Dragonfly nymphs ( Aeshna cyanea) and newt eggs ( Ichthyosaura alpestris) were subjected to fluctuating cold and warm thermal regimes (7-12 and 12-22°C, respectively) and the presence/absence of a predator or prey chemical cues. Preferred body temperatures were measured in an aquatic thermal gradient (5-33°C) over a 24-h period. Newt T increased with developmental temperature irrespective of the presence/absence of predator cues. In dragonflies, thermal reaction norms for T were affected by the interaction between temperature and prey cues. Specifically, the presence of newt scents in cold regime lowered dragonfly T. We concluded that predator-prey interactions influenced thermally-induced plasticity of T but not in a reciprocal fashion. The occurrence of frequency-dependent thermal plasticity may have broad implications for predator-prey population dynamics, the evolution of thermal biology traits, and the consequences of sustaining climate change within ecological communities. [ABSTRACT FROM AUTHOR]

In this study, we applied geometric morphometrics to explore variations in the level and pattern of sexual size dimorphism (SSD) and sexual shape dimorphism (SShD) of the ventral cranium in three different Modern Eurasian newt taxa ( Ichthyosaura alpestris, Triturus species group and Lissotriton vulgaris). The ventral cranium is the part of the skull that is more directly related to foraging and feeding. Our results indicate that the level and pattern of sexual dimorphism in the ventral cranium differ among Modern Eurasian newt taxa. Regarding sexual dimorphism in skull size, Ichthyosaura alpestris and Triturus species show female-biased patterns (females are larger than males), whereas Lissotriton vulgaris appears to be non-dimorphic in skull size. In I. alpestris and Triturus species, SShD is mostly absent, whereas in L. vulgaris, SShD is more pronounced. A high level of variation between populations in both SSD and SShD indicates that local conditions may have a profound effect on the magnitude and direction of sexual dimorphism. The significant sexual differences in ventral cranium size and shape indicate possible subtle intersexual differences in ecological demands due to diet specialisation, in spite of similar general ecological settings. [ABSTRACT FROM AUTHOR]

Many ectotherms possess the ability to behaviourally regulate their body temperatures. Thermoregulatory behaviour is affected by various biotic and abiotic factors, which may cause a substantial bias in the laboratory estimates of preferred body temperatures ( T). We examined thermoregulatory behaviour in alpine newts, Ichthyosaura (formerly Triturus) alpestris, in both horizontal linear and vertical nonlinear thermal gradients, to evaluate the influence of a disparate water temperature distribution on their thermal preferences. Newt positions in thermal gradients differed from those in constant temperatures, which indicates their thermal preferences in both experimental setups. The mean and range of body temperatures showed similar values in both types of aquatic thermal gradients. We concluded that under a sufficiently wide range of environmental temperatures, newt thermal preferences are largely insensitive to the thermal gradient profile. This supports the suitability of T estimates for further experimental and comparative studies in newts. [ABSTRACT FROM AUTHOR]

Oviposition-site choice has profound fitness consequences for both a mother and her offspring. The adaptive significance of oviposition behaviour for both generations depends on two rarely considered assumptions: (1) the fit of maternal oviposition preferences with local phenotypic optimum (adaptive accuracy) and (2) the predictability of future conditions for developing offspring based on conditions at the time of oviposition. We examined both assumptions using temperature oviposition preferences ( T) previously measured under laboratory conditions in the alpine newt, Ichthyosaura (formerly Triturus) alpestris. Analyses of temperature time series in the newt natural environment revealed, in agreement with oviposition-site choice of female newts, that T were closer to phenotypic optima at the water surface than at the maximal depth (bottom). Temperature time series in both depths contained a high proportion of predictable variation, though bottom thermal conditions were more predictable than those at the water surface. We concluded that female newts have to trade the adaptive accuracy of T for the predictability of future thermal conditions at the time of oviposition. [ABSTRACT FROM AUTHOR]

Immunohistochemical study of the expression of recoverin (photoreceptor protein) in the retina of Pleurodeles waltl adult triton was carried out in health, during regeneration after removal, and under conditions of long-lasting detachment. Studies with polyclonal (monospecific) antibodies to recoverin showed that normally it is present in the internal segment, connective cilium, in distal portions of the external segments of cones and rods, and in Landolt clubs of displaced bipolar cells. Detachment of the retina is associated with translocation of recoverin from the photoreceptor processes to perikaryons, and the content of recoverin-positive displaced bipolar cells increases. During regeneration of the retina after its excision via conversion of the pigmented epithelial cells, recoverin is synthesized in the prospective photoreceptor perikaryons and then accumulates in the forming inner segments. Hence, recoverin can serve as a reliable marker in studies of photoreceptor differentiation and functioning during regeneration or survival of the retina. [ABSTRACT FROM AUTHOR]

Abstract  As with many other amphibians, Triturus species are characterized by a biphasic life cycle with abrupt changes in the cranial skeleton during metamorphosis. The post-metamorphic shape changes of the cranial skeleton were investigated using geometric morphometric techniques in six species: Triturus alpestris, T. vulgaris, T. dobrogicus, T. cristatus, T. carnifex, and T. karelinii. The comparative analysis of ontogenetic trajectories revealed that these species have a conserved developmental rate with divergent ontogenetic trajectories of the ventral skull shape that mainly reflect phylogenetic relatedness. A striking exception in the ontogenetic pattern was possibly found in T. dobrogicus, characterized by a marked increase in the developmental rate compared to the other newt species. The size-related shape changes explained a large proportion of shape change during post-metamorphic growth within each species, with marked positive allometric growth of skull elements related to foraging. [ABSTRACT FROM AUTHOR]

In this study, the variety of sugar residues in the gut glycoconjugates of Triturus carnifex (Amphibia, Caudata) are investigated by carbohydrate conventional histochemistry and lectin histochemistry. The oesophageal surface mucous cells contained acidic glycoconjugates, with residues of GalNAc, Gal β1,3 GalNAc and (GlcNAc β1,4) n oligomers. The gastric surface cells mainly produced neutral glycoproteins with residues of fucose, Gal β1-3 GalNAc, Gal-αGal, and (GlcNAc β1,4) n oligomers in N- and O-linked glycans, as the glandular mucous neck cells, with residues of mannose/glucose, GalNAc, Gal β1,3 GalNAc, (GlcNAc β1,4) n oligomers and fucose linked α1,6 or terminal α1,3 or α1,4 in O-linked glycans. The oxynticopeptic tubulo-vesicular system contained neutral glycoproteins with N- and O-linked glycans with residues of Gal-αGal, Gal β1-3 GalNAc and (GlcNAc β1,4) n oligomers; Fuc linked α1,2 to Gal, α1,3 to GlcNAc in (poly)lactosamine chains and α1,6 to GlcNAc in N-linked glycans. Most of these glycoproteins probably corresponds to the H+K+-ATPase β-subunit. The intestinal goblet cells contained acidic glycoconjugates, with residues of GalNAc, mannose/ glucose, (GlcNAc β1,4) n oligomers and fucose linked α1,2 to Gal in O-linked oligosaccharides. The different composition of the mucus in the digestive tracts may be correlated with its different functions. In fact the presence of abundant sulphation of glycoconjugates, mainly in the oesophagus and intestine, probably confers resistance to bacterial enzymatic degradation of the mucus barrier. [ABSTRACT FROM AUTHOR]

Early breeding intraguild predators may have advantages over late breeding predators via priority effects; early breeding predators may reduce shared prey resources before late breeders appear and may also prey upon the late breeders. Here we show that predatory larvae of the late-breeding predatory banded newt, Triturus vittatus vittatus, occupy the same temporary pond toward the end of the developmental period of the early-breeding predatory fire salamander, Salamandra salamandra, resulting in a large size disparity between larvae of these two species while they co-occur. We conducted outdoor artificial pool experiments to assess priority effects of large larval Salamandra at the end of their larval development period, on recently hatched larval Triturus. We also assessed how artificial vegetation may influence larval Triturus performance in the presence or absence of Salamandra Salamandra, introduced into the experimental pools two weeks prior to the newt larvae, strongly reduced invertebrate prey abundance shared by these two predatory urodeles and with only a one week period of overlap, strongly reduced abundance of Triturus larvae. The artificial vegetation had only a small ameliorating effect on Triturus survival when Salamandra was present. Triturus size at metamorphosis (snout-tail length) was significantly larger in the Salamandra pools, presumably due to a combination of a strong “thinning effect” and greater vulnerability of smaller Triturus individuals to predation by Salamandra. Time to metamorphosis was not significantly affected by Salamandra. These results have conservation implications as T. v. vittatus is listed as highly endangered and may also explain the largely negative spatial association of the two species. [ABSTRACT FROM AUTHOR]

No abstract available. [ABSTRACT FROM AUTHOR]

Experiments were carried out to investigate the use of magnetic compass cues in the nocturnal homing orientation of the alpine newt Triturus alpestris. Tests were carried out at a site 9 km to the east–northeast of the breeding pond. Newts were tested at night in an outdoor circular arena that provided an unimpeded view of celestial cues, in one of four symmetrical alignments of an earth-strength magnetic field. In tests carried out under partly cloudy skies newts exhibited homeward magnetic compass orientation. Because the moon was visible in some trials, but obscured by clouds in others, we investigated whether the presence of the moon contributed to the scatter in the distribution of magnetic bearings. When the moon was visible, the distribution of magnetic bearings was more scattered than when the moon was obscured by clouds, although in neither case was the distribution significant due, in part, to the small sample sizes. Moreover, when the moon was visible, newts oriented along a bimodal axis perpendicular to the moon azimuth, suggesting that the presence of the moon may have affected the newts behavior. To provide a more rigorous test of the role of magnetic compass cues when celestial cues were unavailable, nocturnal tests were carried out during the following migratory season under total overcast. In the absence of celestial compass cues, the distribution of magnetic bearings exhibited highly significant orientation in the homeward direction. These findings indicate that newts are able to orient in the homeward direction at night using the magnetic compass as the sole source of directional information. Moon light altered the newts’ behavior. However, this apparently resulted from the asymmetrical distribution of moon light in the testing arena, rather than the use of an alternative compass. [ABSTRACT FROM AUTHOR]

Abstract Genetic variation in 19 populations of the alpine newt, Triturus alpestris, was assessed at the north-eastern margin of its range (southern Poland). Allozyme variation at five polymorphic loci was used in order to evaluate the degree of intrapopulational variation and interpopulational differentiation and define conservation units. Three management units were established on the basis of significant differences in allele frequencies. These correspond to three separate mountain ranges, i.e. the Carpathian, Sudetes and Holy Cross Mts. Contemporary gene flow between them is limited. In the extensively sampled Carpathian Mts, genetic structure is less pronounced, although still significant. Among population differentiation may be attributed to genetic drift in accordance with the isolation by distance model. The consequences of recent changes in land use in Central and Eastern Europe for low vagility and genetically structured organisms are discussed. [ABSTRACT FROM AUTHOR]

The role of acoustic cues as reference cues for orientation by amphibians has been demonstrated in anurans, the only amphibian group that engages in acoustic communication, but not in urodeles. Orientation responses of marbled newts, Triturus marmoratus, were studied to determine whether heterospecific calls elicited positive phonotaxis. The orientation tests consisted in presenting either a familiar acoustic stimulus, the advertisement calls of natterjack toads (Bufo calamita), or a control stimulus, the advertisement calls of European green toads (Bufo viridis) that the newts would not be expected to recognize. Marbled newts and natterjack toads occur in simpatry, but T. marmoratus and B. viridis are allopatric species. Thus, T. marmoratus is distributed over the northern half of the Iberian Peninsula, whereas B. viridis occurs in the Balearic Islands, but not over the Iberian Peninsula. Newts were released in a circular arena while a recorded chorus of natterjack toads or European green toads played outside the arena to determine whether they displayed positive phonotactic orientation. Our results show that marbled newts performed positive phonotaxis when exposed to the breeding calls of natterjack toads, but not to those of European green toads. Newts chose a compass course in the direction of the advertisement calls of B. calamita. Acoustic information might improve orientation accuracy. This study is the first to provide evidence of heterospecific call recognition and positive phonotactic response in urodeles. [ABSTRACT FROM AUTHOR]

The adaptive significance of multiple matings for females is a matter of much controversy. In insects, supplying the female’s sperm reserves with portions of fresh spermatozoa may be the main function of multiple matings. This simple explanation may also be applied to other animals which produce large numbers of eggs over prolonged periods of time. We tested the fertility insurance hypothesis in Montandon’s newt ( Triturus montandoni, Amphibia, Salamandridae). T. montandoni females are inseminated internally by spermatophores they have picked up, and subsequently lay eggs fertilized by spermatozoa released from the spermatheca. We compared the reproductive success of singly and multiply inseminated females of Montandon’s newt in the laboratory. Multiply inseminated females laid more eggs and had a lower percentage of non-developing eggs than females who mated only once. Our data suggest that remating increases the reproductive success of multiply inseminated females by replenishing sperm reserves in the spermatheca or by supplying females with fresh portions of spermatozoa with high fertilizing capacity. [ABSTRACT FROM AUTHOR]

Spectral sensitivity of dark adapted eyes from aquatic and terrestrial animals of Triturus alpestris was determined using the ERG. Spectral sensitivity changes with transition in a different habitat during metamorphosis and in adult animals in a seasonal course. In aquatic animals (larvae and adults in spring) data agree with the absorption curve for porphyropsin P 523. In juvenile and adult terrestrial animals in autumn data fit the absorption curve for rhodopsin P 502. [ABSTRACT FROM AUTHOR]

Palmate newt larvae were exposed to a series of different concentrations of ammonium nitrate under laboratory conditions. Survival data analysis, which took account of the probability that an individual survives beyond a certain time and the likelihood of death as a function of age, was used to model time to death for each of the treatments. Initial mass and ammonium nitrate concentration were found to be highly significant: hazard of death decreased with increased mass and increased ammonium nitrate concentration. These results are discussed in terms of the possible impact of this fertilizer on newt populations in agricultural areas [ABSTRACT FROM AUTHOR]

The present investigation was conducted in an attempt to understand the interrelationships between carcinogenesis and regeneration. The aim was to find out whether chemical carcinogens constitute a class of agents specifically interfering with the normal developmental process during amphibian limb regeneration. To achieve this, the potent chemical carcinogens N-methyl-N′-nitro-N-nitrosoguanidine (MNNG) and N-nitrosodimethylamine (DMN) were inserted at a position slightly proximal to the blastema of regenerating Triturus cristatus forelimbs. The results indicate that, sometimes, the two developmental parameters, growth rate and morphogenesis, were differently affected depending on the treated limb and the carcinogen used. The effect of DMN on regenerative growth rate was negligible, but morphogenesis was highly impaired. Similarly, MNNG-treated stumps displayed abnormal regenerates in both forelimbs, whereas growth rates were significantly affected only in the right forelimbs. The findings are discussed in the framework of the relevant hypotheses. Copyright © 1992 S. Karger AG, Basel [ABSTRACT FROM AUTHOR]

Repeated injections of colchicine into the forearms of normal adult newts led to the disappearance of microtubules within some nerves and a concomitant loss of specialized morphological features at the neuromuscular junction. Within 2 weeks, the postsynaptic folds decreased in height and number, became flattened and eventually disappeared. In addition, nerve terminals in drug-treated animals became separated from the muscle surface and were highly congested with masses of synaptic vesicles. The present findings show that colchicine has an effect on the structural integrity of the neuromuscular junction. These effects could be direct; secondary to retraction of the nerve from the muscle surface; or the result of interference with the proper transport and/or release of neurotrophic substances. [ABSTRACT FROM AUTHOR]

Fine structural observations were made on the vesicle and granule content of ganglion cells in the posterior subclavian ganglion and peripheral nerve fibers of the upper forelimb of the newt Triturus. The populations of vesicles and granules in normal ganglion cells and nerve fibers were compared with those observed after limb transection. In normal neurons, clear vesicles range in size from 250 to 1000 Å in diameter, but are most frequently 400-500 Å. Vesicles with dense contents (granules) also vary greatly in size, but most are 450-550 Å in diameter and correspond to dense-core vesicles. Large granules that contain acid phosphatase activity are thought to be lysosomes. During limb regeneration, in both the ganglion cells and peripheral nerves, the ratio of dense vesicles to clear vesicles increases. There is a large increase in number of dense granules with a diameter over 800 Å, particularly in the peripheral regenerating fibers. This study shows that regenerating neurons differ from normal in their content of vesicular structures, especially large, membrane-bounded granules. [ABSTRACT FROM AUTHOR]

European newts (genus Triturus) are widely studied, but their phylogeny is not yet unambiguously resolved. Fragments of mitochondrial DNA experiencing different rates of evolution (the ATPase and 12S rDNA genes) were sequenced in order to test a phylogenetic hypothesis derived from biochemical and behavioural data. Well supported branches of the existing phylogeny also gained support in our study. Within the subgenus Palaeotriton (the group of small-bodied newts) the monophyletic origin of the hypothesized T. boscai - T. italicus clade remained ambiguous, whereas strong support was gained for the sister-taxon relationship of T. vulgaris and T. montandoni. The position of T. vittatus within the subgenus Triturus as a sister taxon to the clade of big-bodied newts (T. marmoratus and T. cristatus superspecies) was also supported. However, the phylogenetic position of the medium-sized newt, T. alpestris could not be clarified. [ABSTRACT FROM AUTHOR]

Studies the genetic variation in the Italian crested newt Triturus carnifex, and the origin of a non-native population north of the Alps. Genetic distance between species of Triturus; Genetic similarities between Triturus species from Geneva and Tuscany; Indication from comparisons of Trichurus population across the range.