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Newts of the genusTriturus(marbled and crested newts) exhibit substantial variation in the number of trunk vertebrae (NTV) and a higher NTV corresponds to a longer annual aquatic period. Because theTriturusphylogeny has thwarted resolution to date, the evolutionary history of NTV, annual aquatic period, and their potential coevolution has remained unclear. To resolve the phylogeny ofTriturus, we generated a c. 6,000 transcriptome-derived marker data set using a custom target enrichment probe set, and conducted phylogenetic analyses using: 1) data concatenation with RAxML, 2) gene-tree summary with ASTRAL, and 3) species-tree estimation with SNAPP. All analyses produce the same, highly supported topology, despite cladogenesis having occurred over a short timeframe, resulting in short internal branch lengths. Our new phylogenetic hypothesis is consistent with the minimal number of inferred changes in NTV count necessary to explain the diversity in NTV observed today. Although a causal relationship between NTV, body form, and aquatic ecology has yet to be experimentally established, our phylogeny indicates that these features have evolved together, and suggest that they may underlie the adaptive radiation that characterizesTriturus.

Identifying the drivers of population fluctuations in spatially distinct populations remains a significant challenge for ecologists. Whereas regional climatic factors may generate population synchrony (i.e., Moran effect), local factors including the level of density-dependence may reduce the level of synchrony. Although divergences in the scaling of population synchrony and spatial environmental variation have been observed, the regulatory factors that underlie such mismatches are poorly understood.No previous studies have investigated how density-dependent processes and population-specific responses to weather variation influence spatial synchrony at both local and continental scales. We addressed this issue in a pond-breeding amphibian, the great crested newt (Triturus cristatus). We used capture-recapture data collected through long-term surveys in five T. cristatus populations in Western Europe.We found a low level of demographic synchrony at both local and continental levels. Weather has weak and spatially variable effects on survival, recruitment and population growth rate. In contrast, density-dependence was a common phenomenon (at least for population growth) in almost all populations and subpopulations.Our findings support the idea that Moran’s effect is low in species where the population dynamics more closely depends on local factors (e.g. population density and habitat characteristics) than on large-scale environmental fluctuation (e.g. regional climatic variation). Those demographic feature likely have far-reaching consequences for the long-term viability of the spatially structured populations and their ability to response to large-scale climatic anomalies.

[Figure][1] An Italian crested newt ( Triturus carnifex ). Photo credit: Daniel Schwarz. Chewing is second nature for most of us. The only time we don't take it for granted is when our tongue gets caught up in our teeth and it gets a hard bite. According to Egon Heiss from the Friedrich

Habitat loss and fragmentation due to urbanisation and road developments have substantial impacts on amphibian populations and road mitigation measures are increasingly used in order to reduce such risks. However, numerous important questions remain unanswered on the actual effectiveness of such ecological road mitigation projects. We used specially adapted time-lapse recording cameras and a custom image analysis script to monitor the amphibian usage and effectiveness of a multi-tunnel mitigation site in northern England over 4 years and used before-and-after pond survey data to evaluate the mitigation results from a population trend perspective. We monitored four amphibian species, including the European protected great crested newt (Triturus cristatus), the main target of amphibian road mitigation in the UK. Despite substantial evidence of mitigation rejection and U-turn movements inside the tunnels, overall, most amphibians entering tunnels successfully used them to move between the different parts of the site separated by the road. Road fences appeared effective for preventing amphibian road mortality and site connectivity was re-established via the wildlife passage system, with multiple new ponds across the road colonised by amphibians. Unlike frogs and toads, tunnel usage by newts was strongly autumn based, indicating that such systems are mainly suitable for supporting newt dispersal movements between breeding areas. The great crested newt population increased rapidly over the course of the monitoring period, suggesting that, together with habitat replacements and improvements, the road mitigation measures were effective at maintaining site connectivity and as a population conservation measure.

Ben Wielstra introduces Eurasian newts of the genus Triturus.

Tracking individual animals with small-sized passive integrated transponder tags (PIT tags) has become a popular and widespread method, one which can be used for investigating life history traits, including dispersal patterns of small protected animals such as newts. In this study, we tested the applicability of PIT tag usage for individual marking with the Great crested newt (Triturus cristatus) as a model amphibian species, and to test the detection of the newts in nature using a passive telemetry system. Clove oil was used as an anaesthetic before surgery. We implanted PIT tags under the skin of 140 newts. The survival rate of newts was 98.57%. X-ray images were taken to check the exact positions of the PIT tags. Since approximately 15.71% of the newts were capable of expelling the tag from their bodies, tag loss has to be accounted for in future behavioural studies dealing with newts and other amphibians potentially capable of frequent tag expulsion. Lastly, we detected by passive telemetry 97 individuals out of 100 released into a natural breeding pond. Males had higher activity (13 detected males vs 7 females per hour) than females, thus males could be detected if present with more certainty. The result of the movement behaviour showed that e.g. the male of T. cristatus in a breeding pond can travel up to 20 m in 78 seconds. In summary, this promising method could allow the automatic data collection of marked newts in aquatic as well as in terrestrial biotopes, providing data on their dispersal, diurnal activity and movement behaviour.

In human-modified landscapes, little is known about the influence of aquatic habitat types on the demographic structure of residing amphibian populations. In the present paper, we focus on a European flagship urodele species (the great crested newt Triturus cristatus) at the north-western range of its distribution, applying the method of skeletochronology to compare the ages of individuals retrieved from agricultural ponds with individuals retrieved from aquatic sites favourably managed for T. cristatus presence. Median ages ranged between 4.5 and 10.0 years depending on sex and population, and did not differ between the two site categories. Females were on average older than males at both agricultural ponds as well as favourably managed sites. Median ages at sexual maturity (3 years for females and 2 years for males) were 4 years below the most commonly observed age cohort in both sexes, suggesting that young adults regularly forgo reproduction. Mean body size did not differ between agricultural ponds and favourably managed sites. However, the former were characterised by a higher variance in body size, which is possibly linked to more unstable ecological conditions in agricultural settings. Taken together, our findings confirm that under suitable conditions agricultural ponds can harbour sustainable populations, an important finding for the broad-scale conservation management of T. cristatus which does not usually take population demographies into account.\ud Keywords: Demography Great crested newt Skeletochronology Triturus cristatus Urodeles

In vertebrates with complex, biphasic, life cycles, larvae have a distinct morphology and ecological preferences compared to metamorphosed juveniles and adults. In amphibians, abrupt and rapid metamorphic changes transform aquatic larvae to terrestrial juveniles. The main aim of this study is to test whether, relative to larval stages, metamorphosis (1) resets the pattern of variation between ontogenetic stages and species, (2) constrains intraspecific morphological variability, and (3) similar to the "hour-glass" model reduces morphological disparity. We explore postembryonic ontogenetic trajectories of head shape (from hatching to completed metamorphosis) of two well-defined, morphologically distinct Triturus newts species and their F1 hybrids. Variation in head shape is quantified and compared on two levels: dynamic (across ontogenetic stages) and static (at a particular stage). Our results show that the ontogenetic trajectories diverge early during development and continue to diverge throughout larval stages and metamorphosis. The high within-group variance and the largest disparity level (between-group variance) characterize the metamorphosed stage. Hence, our results indicate that metamorphosis does not canalize head shape variation generated during larval development and that metamorphosed phenotype is not more constrained relative to larval ones. Therefore, metamorphosis cannot be regarded as a developmental constraint, at least not for salamander head shape. This is the peer reviewed version of the following article: Vučić T, Sibinović M, Vukov TD, Tomašević Kolarov N, Cvijanović M, Ivanović A. Testing the evolutionary constraints of metamorphosis: The ontogeny of head shape in Triturus newts. Evolution. 2019, which has been published in final form at [http://doi.org/10.1111/evo.13743]. This article may be used for non-commercial purposes in accordance with Wiley Terms and Conditions for Use of Self-Archived Versions.

Food processing refers to any form of food mechanical breakdown prior to swallowing. Variations of this behaviour are found within all major gnathostome groups. Chewing is by far the most commonly used intraoral processing mechanism and involves rhythmic mandibular jaw and hyobranchial (tongue) movements. Chewing occurs in chondrichthyans (sharks and rays), actinopterygians (ray-finned fishes), dipnoi (lungfishes) as well as amniotes and involves similarities in the patterns of muscle activity and movement of the feeding apparatus. It has been suggested that amniote chewing, which involves the interaction of movements of the mandibular jaw and the muscular tongue, has evolved as part of the tetrapod land invasion. However, little is known about food processing mechanisms in lissamphibians, which might have retained many ancestral tetrapod features. Here, we identify a processing mechanism in the salamandrid newt, Triturus carnifex, which after prey capture displays cyclic head bobbing in concert with rhythmic jaw and tongue movements. We use high-speed fluoroscopy, anatomical reconstructions and analyses of stomach content to show that newts, although not using their mandibular jaws, deploy a derived processing mechanism where prey items are rasped rhythmically against the dentition on the mouth-roof, driven by a loop-motion of the tongue. We then compare patterns and coordination of jaw and tongue movements across gnathostomes to conclude that food processing in this newt species shares traits with processing mechanisms in fish as well as amniotes. This discovery casts salamanders as promising models for reconstructing the evolution of intraoral processing mechanisms at the fish-tetrapod split.

International audience; 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.

Hybridization can leave genealogical signatures in an organism's genome, originating from the parental lineages and persisting over time. This potentially confounds phylogenetic inference methods that aim to represent evolution as a strictly bifurcating tree. We apply a phylotranscriptomic approach to study the evolutionary history of, and test for inter-lineage introgression in the Salamandridae, a Holarctic salamanders group of interest in studies of toxicity and aposematism, courtship behavior, and molecular evolution. Although the relationships between the 21 currently recognized salamandrid genera have been the subject of numerous molecular phylogenetic studies, some branches have remained controversial and sometimes affected by discordances between mitochondrial vs. nuclear trees. To resolve the phylogeny of this family, and understand the source of mito-nuclear discordance, we generated new transcriptomic (RNAseq) data for 20 salamandrids and used these along with published data, including 28 mitochondrial genomes, to obtain a comprehensive nuclear and mitochondrial perspective on salamandrid evolution. Our final phylotranscriptomic data set included 5455 gene alignments for 40 species representing 17 of the 21 salamandrid genera. Using concatenation and species-tree phylogenetic methods, we find (1) Salamandrina sister to the clade of the “True Salamanders” (consisting of Chioglossa, Mertensiella, Lyciasalamandra, and Salamandra), (2) Ichthyosaura sister to the Near Eastern genera Neurergus and Ommatotriton, (3) Triturus sister to Lissotriton, and (4) Cynops paraphyletic with respect to Paramesotriton and Pachytriton. Combining introgression tests and phylogenetic networks, we find evidence for introgression among taxa within the clades of “Modern Asian Newts” and “Modern European Newts”. However, we could not unambiguously identify the number, position, and direction of introgressive events. Combining evidence from nuclear gene analysis with the observed mito-nuclear phylogenetic discordances, we hypothesize a scenario with hybridization and mitochondrial capture among ancestral lineages of (1) Lissotriton into Ichthyosaura and (2) Triturus into Calotriton, plus introgression of nuclear genes from Triturus into Lissotriton. Furthermore, both mitochondrial capture and nuclear introgression may have occurred among lineages assigned to Cynops. More comprehensive genomic data will, in the future, allow testing this against alternative scenarios involving hybridization with other, extinct lineages of newts., LR, MH and MVen were supported by the Deutsche Forschungsgemeinschaft (grant VE247/16-1 – HO 3492/6-1) in the framework of the “TaxonOmics” priority program. II was supported by a Juan de la Cierva Incorporación postdoctoral fellowship (IJCI-2016- 29566) from the Spanish Ministry of Economy and Competitiviness (MINECO). ES was supported by the Deutscher Akademischer Austauschdienst (DAAD).

While poorly dispersing taxa such as amphibians may have limited scope to track recent and rapid climate change by means of large range shifts, they may follow their climate envelope with short elevational shifts in mountain areas. Such elevational shifts are poorly documented by empirical data for amphibians. In this study, we analysed a 15-year data series on the distribution of three amphibian species (Bufo bufo, Triturus carnifex and Rana temporaria) inhabiting a mountain pond network in the southern Italian Alps, where temperatures have increased significantly over the last decades. By using multi-season occupancy models, we estimated the occupancy trend of each species over the study period and tested the occurrence of an actual elevational shift after accounting for the probability of false absence. The upper elevational limit of the two eurythermal species (B. bufo and T. carnifex) underwent a significant and progressive upward shift of ca. 200 m. Our results provide evidence of the ability of amphibians to perform rapid elevational shifts, great enough to track predicted rates of climate warming. Preserving and improving habitat connectivity between lowlands and highlands could safeguard the opportunity for such elevational migrations, but mountain aquatic habitats must be preserved in order to provide a safe refuge for amphibians escaping climate warming.

Constructed wetlands are used as an effective measure to improve water quality and reduce nutrient runoff from agriculture. However, their role as alternative breeding sites for different amphibian species is rarely explored. We studied amphibians' colonization and breeding success in two in-stream free surface water wetlands in intensively managed agricultural landscape in south-eastern Estonia. Additionally, the sedimentation pond and a nearby farm pond were observed. The observations started a year after the establishment of the constructed wetlands in 2015 and lasted for four years. In Vanda constructed wetlands, breeding of five amphibian species were observed, all of which were common to the area: smooth newt (Lissotriton vulgaris L.), common toad (Bufo bufo L.), common frog (Rana temporaria L.), moor frog (Rana arvalis Nilsson) and pool frog (Pelophylax lessonae Camerano). Threatened species, such as the common spadefoot toad (Pelobates fuscus Wagler) or the northern crested newt (Triturus cristatus Laur.), also present in this region, were not found in the study sites. Unlike the sedimentation and farm ponds, constructed wetlands with their shallow rapidly warming water and absence of fish, provided breeding habitat for amphibians, especially for common frog and moor frog. In addition, chemical analyses of the water showed that nutrient concentration in the surface water was relatively low, which should not impair the reproduction of amphibians, at least in the short-term.

Human-induced environmental alterations, e.g. the introduction of alien species and the application of management practices, together with climatic change, represent the main threat to worldwide amphibian conservation. Long-term monitoring programmes are mandatory to monitor the status of amphibian populations in changing landscapes and climatic conditions. In this study, we showed the population dynamic of the Italian crested newts Triturus carnifex living in four artificial ponds in Central Italy over a 20-year period. Adult newts were recognised through a capture-mark-recapture protocol, involving the analysis of belly patterns. The first best population model showed a constant newt survival among years and a complete recapture rate; the second supported model showed a sex-dependent survival, with slightly higher values for males with respect to females, and corroborated a complete recapture rate. A high philopatry occurred: we observed less than 10% of individuals dispersing from a birth site to other ponds. In 20 years of continuous monitoring, the population of Italian crested newt increased. The removal of goldfish Carassius auratus from one of the ponds in 2010 allowed adult newts to overwinter within the pond and to have two reproductive periods, with overwintering larvae after the second spawning.

As the biggest inner city national reserve in Germany, the D¨onche in Kassel is characterized by its history and composition of ponds, reeds and varying woodlands. Due to artificial grazing, the structural open landscape with small-area wetland habitats was well preserved. In the last two decades, changes in aquatic ecosystems were becoming more obvious. From originally 400 water filled bomb crater only five are left and while several dry out in late spring or early summer, only three might keep enough water for amphibians to reproduce. After the project group “Amphibien- und Reptilienschutz in Hessen e.v.” (Agar) verified the existence of several amphibian species in the D¨onche in 2002, no further detailed inventory on Salamandridae biodiversity and especially the northern crested newt had been conducted. Because of the long time since any latest survey and an obviously changing situation in the water household, we collected information on populations and species diversity for an inventory covering the entire breeding season between March and July.We followed movements of the great crested newt (Triturus cristatus) using a potentially novel tool for newt tracking using body patterns and analyzed the situation of the common newt (Lissotriton vulgaris) while attempting to get an overview on all present amphibian species with a focus on the water quality and water-cycle. As a result of our study we are stating the worrying condition of local amphibian populations due to a major decline in habitat suitability for all aquatic amphibians in the nature reserve D¨onche, most likely caused by an increase in global temperature.

Genetic pollution through introgressive hybridization of local species by exotic relatives is a major, yet neglected aspect of biological invasions, particularly in amphibians where human introductions are frequent. In Western Switzerland, crested newts make an interesting case: the Italian species Triturus carnifex was introduced at least a century ago within the range of the native and threatened T. cristatus. To understand the genetic consequences of this introduction and inform wildlife management authorities, we conducted a genetic survey on the remaining northern crested newt populations known in the area, using newly-developed species-diagnostic nuclear (microsatellites) and mitochondrial (control region) DNA markers. We documented massive nuclear introgression by the T. carnifex genome, which has completely replaced T. cristatus in most populations, especially in the Geneva area where the introduction was originally reported. However, many of these individuals retained the ancestral T. cristatus mtDNA, which could be explained by asymmetric introgression between the two species, stemming from demographic and/or selective processes. Analyses of genetic diversity support multiple events of T. carnifex releases, most-likely of proximate North Italian origin. We pinpointed the last indigenous populations in the region and recommend to prioritize their protection. Our study demonstrates the invasive potential of introduced taxa through introgressive hybridization, alerts about the underestimated rate of illegal amphibian translocations, and emphasizes the need for genetic analyses to monitor such invasions.

Shelters are important for animal survival. Provision of adequate hiding places allow animals to express their natural sheltering behavior and it can have different positive effects on cortisol levels, physiological processes and mental performance. Although the absence of a refuge activates some stress response, its effect on oxidative stress has not been adequately examined. This study investigated whether the presence/absence of a shelter modifies the oxidative status (the antioxidant system and oxidative damage) and aggressive behavior of crested newt larvae (Triturus macedonicus and its hybrid with T. ivanbureschi). Our results show that individuals reared with shelters had lower values of the tested antioxidant parameters (catalase, glutathione peroxidase, glutathione S-transferase and glutathione), indicating a lower production of reactive species than individuals reared without shelter. The same pattern was observed in both T. macedonicus and its hybrid. Contrary to the activation of some physiological pathways, shelter availability did not significantly affect the rate of intraspecific aggressive behavior. The physiological benefits of shelter use can be manifested as a lower requirement for investment in the energy necessary for the maintenance of the upregulated antioxidant defenses, activation of repair systems and synthesis of endogenous antioxidants. This study highlights the importance of shelter provision, which may be valuable in habitat restoration and animal conservation studies.

In the last few years, DNA barcoding became an established method for species identification in biodiversity inventories and monitoring studies. Such studies depend on the access to a comprehensive reference data base, covering all relevant taxa. Here we present a comprehensive DNA barcode inventory of all amphibian and reptile species native to Austria, except for the putatively extinct Vipera ursinii rakosiensis and Lissotriton helveticus, which has been only recently reported for the very western edge of Austria. A total of 194 DNA barcodes were generated in the framework of the Austrian Barcode of Life (ABOL) initiative. Species identification via DNA barcodes was successful for most species, except for the hybridogenetic species complex of water frogs (Pelophylax spp.) and the crested newts (Triturus spp.), in areas of sympatry. However, DNA barcoding also proved powerful in detecting deep conspecific lineages, e.g. within Natrix natrix or the wall lizard (Podarcis muralis), resulting in more than one Barcode Index Number (BIN) per species. Moreover, DNA barcodes revealed the presence of Natrix helvetica, which has been elevated to species level only recently, and genetic signatures of the Italian water frog Pelophylax bergeri in Western Austria for the first time. Comparison to previously published DNA barcoding data of European amphibians and reptiles corroborated the results of the Austrian data but also revealed certain peculiarities, underlining the particular strengths and in the case of the genus Pelophylax also the limitations of DNA barcoding. Consequently, DNA barcoding is not only powerful for species identification of all life stages of most Austrian amphibian and reptile species, but also for the detection of new species, the monitoring of gene flow or the presence of alien populations and/or species. Thus, DNA barcoding and the data generated in this study may serve both scientific and national or even transnational conservation purposes.

International audience; Dispersal (i.e. movement from a natal or breeding site to another breeding site) is a central process in ecology and evolution as it affects the eco-evolutionary dynam- ics of spatially structured populations. Dispersal evolution is regulated by the bal- ance between costs and benefits, which is influenced by the individual phenotype (i.e. phenotype-dependent dispersal) and environmental factors (i.e. condition-dependent dispersal). Even though these processes have been extensively studied in species with simple life cycles, our knowledge about these mechanisms in organisms displaying complex life cycles remains fragmentary. In fact, little is specifically known about how the interplay between individual and environmental factors may lead to alternative dispersal strategies that, in turn, lead to the coexistence of contrasted site fidelity phe- notypes. In this paper, we examined breeding dispersal in a pond-breeding amphibian, the great crested newt Triturus cristatus, within usual walking distances for a newt. We took advantage of recent developments in multi-event capture–recapture models and used capture–recapture data (946 newts marked) collected in a spatially structured population occupying a large pond network (73 ponds). We showed a high rate of breeding site infidelity (i.e. pond use) and the coexistence of two dispersal phenotypes, namely, a highly pond faithful phenotype and a dispersing phenotype. Individuals that were site faithful at time t – 1 were therefore more likely to remain site faithful at time t. Our results also demonstrated that the probability that individuals belong to one or the other dispersal phenotypes depended on environmental and individual factors. In particular, we highlighted the existence of a dispersal syndrome implying a covariation pattern among dispersal behavior, body size, and survival. Our work opens new research prospects in the evolution of dispersal in organisms displaying complex life cycles and raises interesting questions about the evolutionary pathways that contribute to the diversification of movement strategies in the wild.

The brain-microvascular architecture of the newt (Triturus cristatus carnifex) was studied by scanning electron-microscopical examination of microvascular corrosion casts. It is characterized at the leptomeningeal level by a superficial network of single vessels that leave the meningeal sheath to form hairpin-shaped capillary loops. These loops penetrate the nervous parenchyma to varying depths and are variously bent, inclined, and twisted. Each hairpin-like loop consists of descending and ascending limbs connected by a distal U-shaped segment. The limbs are of equal diameter and lack physical differentiation. Some loops branch in a secondary loop, but there are no intraparenchymal connections with analogous surrounding structures. On vascular casts we observed detailed imprints of endothelial cell nuclei. This microvascular architecture is present in the whole brain except in leptomeninx and choroidal plexuses. The vascular pattern of T. cristatus carnifex resembles that of apodans. However, it differs from the anuran condition, which is characterized by a three-dimensional parenchymal network and from that of Ambystoma mexicanum which displays an intermediate condition between a single-capillary network and a capillary-loop model. At the level of paired capillaries, a counter-current exchange system may occur between the two limbs of the same loop, an arrangement that could promote uniformity of extracellular fluid composition in parenchyma.

Oxidative stress has most recently been suggested as one of the possible mechanisms responsible for reduced fitness of hybrids. To explore possible oxidative cost of hybridization, we examined anti-oxidant defence system parameters (superoxide dismutase, catalase, glutathione peroxidase, glutathione

The use of aquatic environmental DNA (eDNA) to detect the presence of species depends on the seasonal activity of the species in the sampled habitat. eDNA may persist in sediments for longer than it does in water, and analysing sediment could potentially extend the seasonal window for species assessment. Using the great crested newt as a model, we compare how detection probability changes across the seasons in eDNA samples collected from both pond water and pond sediments. Detection of both aquatic and sedimentary eDNA varied through the year, peaking in the summer (July), with its lowest point in the winter (January): in all seasons, detection probability of eDNA from water exceeded that from sediment. Detection probability of eDNA also varied between study areas, and according to great crested newt habitat suitability and sediment type. As aquatic and sedimentary eDNA show the same seasonal fluctuations, the patterns observed in both sample types likely reflect current or recent presence of the target species. However, given the low detection probabilities found in the autumn and winter we would not recommend using either aquatic or sedimentary eDNA for year-round sampling without further refinement and testing of the methods.

In 1924, Hans Spemann and Hilde Mangold (née Pröscholdt) published their famous work describing the transplantation of dorsal blastopore lip of one newt gastrula embryo onto the ventral side of a host embryo at the same stage. They performed these grafts using two newt species with different pigmentation (Triturus taeniatus and Triturus cristatus) to follow the fate of the grafted tissue. These experiments resulted in the development of conjoined twins attached through their belly. Because of the difference in embryo pigmentation between the two Triturus species, they determined that the bulk of the secondary embryo arose from the host embryo while the grafted tissue per se gave increase to the notochord and a few somitic cells. This meant that the dorsal blastopore lip was able to organize an almost complete embryo out of ventral tissue. The dorsal blastopore lip is now called the Spemann–Mangold organizer. Here, we describe a simple yet efficient protocol to perform these grafts using the anuran Xenopus laevis.

Oxidative stress has most recently been suggested as one of the possible mechanisms responsible for reduced fitness of hybrids. To explore possible oxidative cost of hybridization, we examined anti-oxidant defence system parameters (superoxide dismutase, catalase, glutathione peroxidase, glutathione S -transferase, glutathione reductase, glutathione, SH groups), their interconnectedness (index of integration) and levels of oxidative damage [concentrations of lipid peroxides, TBARS (thiobarbituric acid reactive substances)] in laboratory-reared newt species, Triturus macedonicus and T. ivanbureschi , and their hybrid. Our results showed that parental species differed in anti-oxidant defence system parameters, but not in the levels of integration of the whole system and oxidative damage. Individuals of T. ivanbureschi had higher activities of superoxide dismutase, glutathione S -transferase and concentrations of glutathione. Hybrid individuals of crested newts displayed higher levels of the anti-oxidant defence system (higher superoxide dismutase, catalase, glutathione peroxidase activities and concentrations of SH groups), and a lower overall correlation of anti-oxidant system (lower index of integration) in comparison with both parental species, suggesting that they may possess a less efficient anti-oxidant defence system and a higher investment in maintaining oxidative balance. The higher investment in the anti-oxidant system could divert limited resources away from other functions and affect further hybrid fitness. The presented findings contribute to a better understanding of the anti-oxidant defence system of crested newts and their interspecies differences, and support the hypothesis that oxidative stress is one of the costs of interspecific hybridization.

Many studies have yet been conducted on suction feeding in aquatic salamander species. Within the Salamandridae, the crested newt Triturus dobrogicus (Kiritzescu, 1903), occurring from the Austrian Danube floodplains to the Danube Delta, was not subject of investigations so far. The present study examines the kinematics of aquatic suction feeding in this species by means of high-speed videography. Recordings of five individuals of different size and sex while feeding on bloodworms were conducted, in order to identify potential discrepancies among individuals and sizes. Five coordinate points were digitized from recordings of prey capture and twelve time- and velocity-determined variables were evaluated. All specimens follow a typical inertial suction feeding process, where rapid hyoid depression expands the buccal cavity. Generated negative pressure within the buccal cavity causes influx of water along with the prey item into the mouth. Results demonstrate higher distance values and angles for gape in individuals with smaller size. In addition, hyoid depression is maximized in smaller individuals. While Triturus dobrogicus resembles a typical inertial suction feeder in its functional morphology, intraspecific differences could be found regarding the correlation of different feeding patterns and body size.

Construction of artificial overwintering habitats, hibernacula, or newt hotels, is an important mitigation measure for newt populations in urban and agricultural areas. We have monitored the use of four artificial hotels built in September 2011 close to a 6000 m2 breeding pond in Norway. The four hotels ranged from 1.6 to 12.4 m3 and were located from 5 to 40 m from the breeding pond. In 2013&ndash, 2015, 57 Great Crested Newts (Triturus cristatus) and 413 Smooth Newts (Lissotriton vulgaris) spent the winter in the hotels. The proportions of juveniles were 75% and 62%, respectively, and the hotels may be important to secure recruitment. Knowledge on emigration routes and habitat quality for summer use and winter hibernation is important to find good locations for newt hotels. The study documented that newts may survive a minimum temperature of &minus, 6.7 &deg, C. We recommend that newt hotels in areas with harsh climate are dug into the ground in slopes to reduce low-temperature exposure during winter.

Understanding how species have replaced each other in the past is important to predicting future species turnover. While past species replacement is difficult to detect after the fact, the process may be inferred from present-day distribution patterns. Species with abutting ranges sometimes show a characteristic distribution pattern, where a section of one species range is enveloped by that of the other. Such an enclave could indicate past species replacement: when a species is partly supplanted by a competitor, but a population endures locally while the invading species moves around and past it, an enclave forms. If the two species hybridize and backcross, the receding species is predicted to leave genetic traces within the expanding one under a scenario of species replacement. By screening dozens of genes in hybridizing crested newts, we uncover genetic remnants of the ancestral species, now inhabiting an enclave, in the range of the surrounding invading species. This independent genetic evidence supports the past distribution dynamics we predicted from the enclave. We suggest that enclaves provide a valuable tool in understanding historical species replacement, which is important because a major conservation concern arising from anthropogenic climate change is increased species replacement in the future.

Initial orientation of crested newts Triturus cristatus and smooth newts Lissotriton vulgaris was measured following passive displacement to arenas placed at 12 test sites 0.213–24.2 km distant from the breeding pond. Newts were transported by car without visual and olfactory outward journey information, but had full access to local orientation clues at the release site during the night and early morning before testing. Within the area of previous migratory experience, the initial directional choice of both species was significantly directed to home. Outside the area of familiarity, the initial orientation was indistinguishable from random in all but one site each at 3 and 20 km distance, respectively. We suggest that short-distance orientation was probably based on olfactory beaconing and on a learned spatial map integrating visual and olfactory information. The failure of homeward orientation following long-distance displacement indicates the absence of a spatial map which allows for extrapolation into ...

Landscapes and their structure are important in shaping the distribution of species and the composition of communities. Since a landscape contains elements that are less permeable to dispersal, species use corridors of habitat suitable to movements that maintain the genetic flow among populations. Corridors have been widely used in conservation biology, but less often to study the connectivity between species’ allopatric ranges. In this study, we analyzed the distribution and connectivity patterns of the Danube Crested Newt (Triturus dobrogicus), a species found in the Danube river basin and whose range is separated by the Carpathian Mountains in two regions, eastern and western. Despite the geographical barrier and clear morphological differentiation between the populations of the two regions, recent genetic analyses suggest maintenance of genetic flow. The aims of our study were (1) to estimate the dispersal ability of the Danube Crested Newt and the connectivity (via corridors) between populations and (2) to identify possible pathways used by the species to cross the Carpathian Mountains barrier. We found that the landscape facilitates a higher population connectivity in the western range than in the eastern range of the species. Moreover, we identified two major migration pathways, along the Iron Gate Canyon and the Timis – Cerna Gap, that may connect all known occurrences from the two regions separated by the Carpathian Mountains. As an alternative dispersal hypothesis, we also discussed the possibility that the Danube Crested Newt is passively dispersed by water, down the Danube river flow direction. Our study provides support for the assertion that even when a species’ distribution is separated in two ranges by a geographical barrier, connectivity between populations via corridors can persist.

Genetic pollution of a native species through hybridization with an invasive species poses an insidious conservation threat. To expose genetic pollution, molecular methods employing multilocus data are required. We present a case study of genetic pollution via hybridization of a native crested newt species, Triturus cristatus, by the invasive Triturus carnifex on the Veluwe in the Netherlands. We sequenced 50 nuclear markers by next generation sequencing and one mitochondrial marker by Sanger sequencing for four populations from the native range of both parent species and eleven ponds on the Veluwe. We use three population genetic approaches (HIest, BAPS and Structure) to determine the genetic composition of the Veluwe newts based on all nuclear markers, a subset of 18 diagnostic markers and the complementary 32 non-diagnostic markers, with and without parental populations. BAPS underestimates genetic pollution, whereas Structure is comparatively accurate compared to HIest, although Structure’s relative advantage decreases with the diagnosticity of the markers. Data simulation confirms these findings. Genetic composition of the Veluwe ponds ranges from completely native, via different degrees of genetic admixture, to completely invasive. The observed hybrid zone appears to be bimodal, suggesting negative selection against hybrids. A genetic footprint of the native species is present in invasive populations, evidencing that the invasive locally replaced the native species. Genetic pollution is currently confined to a small area, but the possibility of further expansion cannot be excluded. Removal of genetic pollution will not be easy. We emphasize the need for legal guidance to manage genetic pollution. 2015 The Authors. Published by Elsevier Ltd. This is an open access article under the CC BY-NC-ND license

Digit ratio (2D:4D) denotes the relative length of the second and fourth digits. It is considered to be a suitable biomarker of the in utero balance of fetal sex hormones, which affect early development of individuaĺs behavioral and morphological characteristics. In recent decades, digit ratio attracted a great attention in biology and psychology. However, for unmasking the biological basis of the phenomenon, extensive studies on non-human animals are necessary. Despite it was hypothesized that digit ratio is well conserved in all Tetrapoda, and there exist studies on mammals, birds, and reptiles, there are only two such study on anuran amphibians. Therefore, the aim of this study is to investigate the 2D:4D in the most basal salamanders, Caudata. We have studied digit ratio in four species of newts: Triturus cristatus, Mesotriton alpestris, Lissotriton montandoni, and Lissotriton vulgaris, using museum collection. We used computerized measuring of each limbś photos. We have found out that, in M. alpestris, females 2D:4D of all four limbs were significantly larger than in males. In L. montandoni and L. vulgaris, only 2D:4D of rear limbs significantly differed, in females being larger. In T. cristatus, digit ratios of males and females did not statistically differ. Thus, the results confirmed our hypothesis that at least in M. alpestris, L. montandoni, and L. vulgaris, females seem to have larger 2D:4D comparing to males, the pattern known from most mammals and opposite to birds, reptiles and anuran amphibians. Anat Rec, 298:1424–1430, 2015. © 2015 Wiley Periodicals, Inc.

The use of environmental DNA (eDNA) is rapidly emerging as a potentially valuable survey technique for rare or hard to survey freshwater organisms. For the great crested newt (Triturus cristatus) in the UK, the substantial cost and manpower requirements of traditional survey methods have hampered attempts to assess the status of the species. We tested whether eDNA could provide the basis for a national citizen science-based monitoring programme for great crested newts by (i) comparing the effectiveness of eDNA monitoring with torch counts, bottle trapping and egg searches and (ii) assessing the ability of volunteers to collect eDNA samples throughout the newt’s UK range. In 35 ponds visited four times through the breeding season, eDNA detected newts on 139 out of 140 visits, a 99.3% detection rate. Bottle traps, torch counts and egg searches were significantly less effective, detecting newts 76%, 75% and 44% of the time. eDNA was less successful at predicting newt abundance being positively, but weakly, correlated with counts of the number of newts. Volunteers successfully collected eDNA samples across the UK with 219 of 239 sites (91.3%) correctly identified as supporting newts. 8.7% of sites generated false negatives, either because of very small newt populations or practical difficulties in sample collection. There were no false positives. Overall, we conclude that eDNA is a highly effective survey method and could be used as the basis for a national great crested newt monitoring programme.