Triturus Research Articles

The Crested Newt. A Dwilling Pond-Dweller

The Crested Newt. A Dwilling Pond-Dweller

Amphibians of the “Cilento e Vallo di Diano” National Park (Campania, Southern Italy): updated check list, distribution and conservation notes

In this study, we present the results of our field and bibliographic survey on the amphibians of the “Cilento and Vallo di Diano” National Park (Southern Italy). Two hundred and thirty three spawning sites (167 original and 66 derived from literature), and 11 amphibian species were found. Reproductive activity was recorded for Salamandra salamandra , Salamandrina terdigitata , Triturus carnifex , Lissotriton italicus , Bufo bufo , Hyla intermedia , Rana italica , Rana dalmatina and Pelophylax synkl. hispanica . The distribution record of many species is widely improved with respect to bibliographic data. Our results also suggested that preservation and restoration of small aquatic sites, in particular of the artificial ones, such as stony wells and drinking-troughs, are fundamental for an appropriate conservation management of amphibians in the “Cilento and Vallo di Diano” National Park.

Estimating the propagule size of a cryptogenic crested newt population

AbstractEncountering cryptogenic populations that are either native or introduced is a common but underreported phenomenon in field biology. Such local species' occurrences of unknown origin hamper our understanding of species' natural distribution ranges, and pose a problem to conservation management decisions. Genetic tools are frequently used to infer the ancestry of natural or invasive populations based on spatial geographical variation. Here we describe the occurrence of cryptogenic crested newts Triturus cristatus c. 25 km away from their main range and situated in an area where an introduction has taken place half a century ago. We first verify the suitability of a coalescent‐based analysis that reconstructs the number of founder individuals of a putative propagule from a source pool, based on previously published data documenting a well‐known introduction (the Laysan finch on the Hawaiian archipelago). After showing the validity of the approach, we apply this analysis to the case of T. cristatus, revealing that the number of effective founders would have been of the same order as the current effective carrying capacity of the population. We thus argue that the local T. cristatus occurrence is in fact of natural origin, with the documented introduction having little or no impact to the current gene pool. The result has major implications to our understanding of the species' habitat requirements in a zone of parapatry with a closely related species.

A comparison of external and internal attachments of radio transmitters on adult crested newts Triturus cristatus

AbstractTelemetry studies of newt species demand small transmitters. Two types of external attachments (sutured to epidermis and backpack) and traditional implanting in the peritoneal cavity were tested between groups of 5 adult individuals of the crested newt Triturus cristatus (mass 6-15 g) held in terrariums under controlled environmental conditions. The newts were anaesthetized with 1.5 g l–1 MS222, delivered in water and buffered to pH 6.9 by Na2CO2. Surgical plane of anaesthesia was achieved after 5-12 minutes and lasted for 30-60 minutes. External tagging proved unsuitable because transmitters became entangled in vegetation, and all animals shed their transmitters shortly after tagging, except for one that died. Transmitters that were surgically implanted in the peritoneal cavity were more successful. By the fourth day following surgery, the animals that had undergone surgery behaved similarly to control animals with respect to the use of cover. Two of the newts died, however, without showing any signs of illness in advance, and the cause of death could not be established. Based on the present experiments and published studies, implantable transmitters appear to be the best method for radiotagging small and medium sized urodele species such as T. cristatus, to gain crucial information on spatio-temporal terrestrial activity patterns, habitat utilization and hibernation sites. Additional research is needed to evaluate both short and long term effects on activity, behaviour and survival.

Terry Burke - recipient of the 2009Molecular EcologyPrize

Terry Burke - recipient of the 2009<i>Molecular Ecology</i>Prize

Age, Size and Growth in Two Populations of the Southern Crested Newt, Triturus karelinii (Strauch 1870) from Different Altitudes

We measured body size of individuals from two populations of the southern crested newt, Triturus karelinii, from two localities at different altitudes (7 m, Klaros and 1373 m, Reşadiye) in Turkey. Lines of arrested growth (LAGs) recorded in phalanges were used to estimate the age of juveniles and adults. Females were on average larger than males in Klaros, and males were on average larger than females in Reşadiye. Our results did not follow the Bergmann's rule and developmental temperature-size rule: for both sexes, the individuals of lowland population were larger than the individuals of highland population. Significant differences were found between the populations in terms of mean SVL (snout–vent length). The average age was calculated as 6.14 ± 1.51 and 6.16 ± 1.46 yr in Klaros and 5.30 ± 1.20 and 5.76 ± 1.26 yr in Reşadiye, for males and females respectively. No significant differences were found between the age distributions of the females in both populations. Both sexes from lowland population had age distributions that were similar to their counterparts from highland population. The growth curves for T. karelinii populations were well described in a Von Bertalanffy growth model. K was not significantly different between the sexes. However, SVLmax was significantly larger in females than males in both populations

A combination of techniques proves useful in the development of nuclear markers in the newt genus Triturus

To increase the number of markers available for study of phylogeny and phylogeography in the newt genus Triturus, we developed and tested 59 primer pairs using three different techniques. Primers were obtained from published sources, by designing exon-primed intron-crossing primers and from randomly cloned anonymous nuclear DNA fragments. Successful polymerase chain reaction products were cloned and sequenced. Five fragments were successfully amplified and sequenced for six species of Triturus: intron 7 of the β-fibrinogen gene (βfibint7), third intron of the calreticulin gene (CalintC), the 11th intron of the α-subunit of the platelet derived growth factor receptor (PDGFRα) and two anonymous markers (Cri1 and Cri4). The average percentage species divergence across all the markers is low (c. 3%), compared to what has been found in mitochondrial DNA (25-30%).

Multiple nuclear and mitochondrial genes resolve the branching order of a rapid radiation of crested newts ( Triturus, Salamandridae)

Newts of the genus Triturus are parapatrically distributed across Europe. Within this group, the crested newts ( Triturus cristatus superspecies) radiated in a short temporal interval. Given the relatively short timespan in between branching events and to address the gene tree—species tree problem, we sequenced two mitochondrial and five nuclear genes from populations representing the distribution range of all the five crested newt species. We built gene trees using non-hierarchical Bayesian phylogenetics and phylogenetic networks, and a species tree with a recently developed method, which uses a hierarchical Bayesian approach. While the single gene trees did not provide resolution, the hierarchical Bayesian method yielded an almost fully resolved species tree, even though branching events followed one another closely. Results show a previously undetected basal dichotomy between T. karelinii and the other four species and a deep differentiation of T. karelinii in two lineages, here raised to full species status.

Skull size and shape variation versus molecular phylogeny: a case study of alpine newts (Mesotriton alpestris, Salamandridae) from the Balkan Peninsula

We explored the phylogenetic signal of skull size and shape in alpine newts from the Balkans, a group of European newts that, in spite of their considerable phylogeographic substructuring (as inferred from previous DNA analyses), maintain a conserved phenotype. In terms of skull shape disparity, geometric morphometrics show that the dorsal cranium carries a significant phylogenetic signal, the most notable evidence in this present study. On the contrary, no phylogenetic signal in the shape of the ventral cranium was found. This result indicates that the variation in the shape of the ventral cranium is more prone to other factors and processes, such as adaptations to local environments rather than phylogenetic constraints. Variation in skull size within alpine newts seems to be independent from phylogenetic constraints.

Sexual Size Dimorphism in Genus Triturus Rafinesque, 1815 (Amphibia: Salamandridae) in Bulgaria—Preliminary Results

ABSTRACTWe studied a sexual size dimorphism (SSD) in three species from the genus Triturus. We used fifteen body measures for calculating the SSD. We performed the multivariate SSD index to calculate the dimorphism in overall body size. We found a well express female-biased SSD in T. karelinii, and male-biased in T. macedonicus. In T. cristatus we also found a male-biased SSD but weakly pronounced. In general SSD possess similar values but is express by different traits. The tendencies of displaying the sexual dimorphism in all the species are also similar. It is still not clear which factors affect the sexual dimorphism in newts.

Sexual size dimorphism in the evolutionary context of facultative paedomorphosis: insights from European newts

BackgroundSexual size dimorphism (SSD) is a key evolutionary feature that has been studied in many organisms. In a wide range of species, this pattern is more complex because of polymorphism within each sex. However, it is not known whether the magnitude and direction of SSD could be affected by alternative developmental trajectories within sexes. Our aim was to test whether an intrasexual polymorphism, facultative paedomorphosis (a process in which the development of somatic and gonadal tissues differs in alternative morphs), could affect SSD variation patterns in European newts.ResultsWe report here the first evidence that SSD varies depending on the paedomorphic or metamorphic ontogenetic pathway. In species with a consistent female-biased SSD, paedomorphosis decreased the SSD level, but did not affect its direction. In species with moderate female-biased SSD or variable SSD patterns, paedomorphosis changed the magnitude, or both the magnitude and the direction, of SSD.ConclusionOur study highlights the importance of developmental processes for shaping SSD patterns in populations in which contrasting life-history pathways evolved. European newts express different SSD patterns depending on their developmental pathway (i.e., metamorphosis versus paedomorphosis), as well as their species and population. These findings emphasize the importance of studying alternative morphotypes, which are found in a wide range of animal groups, to understand the evolution of SSD.

A multi-scale approach to facultative paedomorphosis of European newts (Salamandridae) in the Montenegrin karst: Distribution pattern, environmental variables, and conservation

Facultative paedomorphosis, a process in which newt larvae can opt for reproduction before or after metamorphosis, is geographically heterogeneous. Despite numerous ecological studies and recent evidence of declines in paedomorphic populations, however, no attempt to model environmental variables that explain the presence of paedomorphs has been made at a multi-scale level. Our aim was to fill this gap in studying three newt species ( Lissotriton vulgaris, Mesotriton alpestris, and Triturus macedonicus) of the Montenegrin karst as model species. To this end, we used multivariate analysis on three scales of habitat: the breeding pond, the land use and the climatologic features. Results show that the study area is both an important hotspot for paedomorphosis and where intraspecific diversity is quickly disappearing (20–47% extirpation) because of fish introductions. Other habitat variables (water permanency, pH or the habitat origin) were shown to act on paedomorphosis but not consistently across species, confirming complexity of the evolutionary and ecological processes. This study appeals for more long-term and detailed landscape studies of polyphenisms, a neglected but promising topic, to better understand and protect alternative modes of development. Particularly, measures should be taken to identify hotspots of intraspecific diversity at a global scale and stop fish introductions before we reach a point of no-return.

Sexual size and shape evolution in European newts (Amphibia: Caudata: Salamandridae) on the Balkan Peninsula

We used a phylogenetic perspective in an examination of the direction and extent of sexual dimorphism in body size and body shape in European newts from the Balkan Peninsula (alpine newts, Mesotriton alpestris; crested newts, Triturus cristatus superspecies; smooth newts, Lissotriton vulgaris). We found a strong, female-biased sexual size dimorphism (SSD) in the analysed clades of alpine newt, whereas within crested newts we found a less stringent female-biased SSD in Triturus carnifex, Triturus macedonicus and Triturus karelinii, and no significant SSD in T. cristatus or Triturus dobrogicus. Among the smooth newts, we found male-biased SSD in Lissotriton vulgaris vularis and Lissotriton vulgaris greacus and no SSD in Lissotriton vulgaris meridionalis. Most of these newts also exhibit a significant sexual dimorphism in body shape, which varied more randomly than body size, regardless of SSD level. Female and male body size as well as the degree of SSD displayed statistically significant phylogenetic signal, while sexual dimorphism in body shape was phylogenetically independent. The relationship between independent contrast data for female size and male size indicated that SSD in European newts could be driven by a disproportionate increase in female size as increase in female size was not accompanied by a proportional increase in male size.

Distribution patterns and environmental determinants of European newts in the Montenegrin karst area

The distribution patterns of three European newt species (Triturus macedonicus, Lissotriton vulgaris, and Mesotriton alpestris) was determined in the Montenegrin karst region and the influence of breeding ponds, the adjacent landscape, and climate variables on distributions within the framework of allotopy vs. syntopy occurrences was tested. After surveying 145 newt breeding sites in a 10,080 km2 area, the ranges of T. macedonicus and M. alpestris were found not come into contact, while L. vulgaris, the most widely distributed species, covers the entire range of T. macedonicus and the lower part of the range of M. alpestris. Using Akaike’s Information Criterion (AIC) to evaluate the effectiveness of 70 a priori models in predicting the presence of the three newt species, it was found that: (1) elevation is the most important variable in predicting newt presence; (2) only a few elevation-dependent variables can replace elevation in the building of a good descriptive model; (3) precipitation in combination with elevation contributes significantly to the building of a better descriptive model; and (4) in comparison with allotopy, syntopy mostly occurs at intermediate elevation ranges of species in sympatry.

Phylogeny and biogeography of the family Salamandridae (Amphibia: Caudata) inferred from complete mitochondrial genomes

Phylogenetic relationships of members of the salamander family Salamandridae were examined using complete mitochondrial genomes collected from 42 species representing all 20 salamandrid genera and five outgroup taxa. Weighted maximum parsimony, partitioned maximum likelihood, and partitioned Bayesian approaches all produce an identical, well-resolved phylogeny; most branches are strongly supported with greater than 90% bootstrap values and 1.0 Bayesian posterior probabilities. Our results support recent taxonomic changes in finding the traditional genera Mertensiella, Euproctus, and Triturus to be non-monophyletic species assemblages. We successfully resolved the current polytomy at the base of the salamandrid tree: the Italian newt genus Salamandrina is sister to all remaining salamandrids. Beyond Salamandrina, a clade comprising all remaining newts is separated from a clade containing the true salamanders. Among these newts, the branching orders of well-supported clades are: primitive newts ( Echinotriton, Pleurodeles, and Tylototriton), New World newts ( Notophthalmus-Taricha), Corsica-Sardinia newts ( Euproctus), and modern European newts ( Calotriton, Lissotriton, Mesotriton, Neurergus, Ommatotriton, and Triturus) plus modern Asian newts ( Cynops, Pachytriton, and Paramesotriton).Two alternative sets of calibration points and two Bayesian dating methods (BEAST and MultiDivTime) were used to estimate timescales for salamandrid evolution. The estimation difference by dating methods is slight and we propose two sets of timescales based on different calibration choices. The two timescales suggest that the initial diversification of extant salamandrids took place in Europe about 97 or 69 Ma. North American salamandrids were derived from their European ancestors by dispersal through North Atlantic Land Bridges in the Late Cretaceous (∼69 Ma) or Middle Eocene (∼43 Ma). Ancestors of Asian salamandrids most probably dispersed to the eastern Asia from Europe, after withdrawal of the Turgai Sea (∼29 Ma).

In the Abdominal Glands of the Smooth Newt (Lissotriton vulgaris) and Montandon’s Newt (L. montandoni) (Salamandridae)

The smooth newt (Lissotriton "Triturus" vulgaris) and Montandon's newt (L."T." montandoni) are sister species exhibiting pronounced differences in male secondary sexual traits but nevertheless hybridizing and producing fertile hybrids in nature. Since pheromonal communication is an important aspect of the reproductive biology of urodeles, structural differentiation of peptide pheromones and their receptors may contribute to incipient reproductive isolation. The aim of the study was the identification of genes encoding putative courtship pheromone precursors in two newt species and the reconstruction of phylogenetic relationships among them. Our analyses were based on cDNA obtained from the transcripts from the abdominal glands of male newts. We identified five unique cDNA sequences encoding the putative pheromone precursors in L. vulgaris and three additional unique sequences in L. montandoni. The results indicate that in the abdominal glands of Lissotriton newts more than one pheromone-encoding gene is expressed and that these loci form a gene family. Phylogenetic analysis indicates that the divergence of at least some of these genes predates the radiation of European newts.

The evolution of thermal performance curves in semi-aquatic newts: Thermal specialists on land and thermal generalists in water?

The position and shape of thermal performance curves (TPCs, the functions relating temperature to physiological performance) for ecologically relevant functions will directly affect the fitness of ectotherms and therefore should be under strong selection. However, thermodynamic considerations predict that relationships between the different components of the TPC will confound its evolutionary optimization. For instance, the “jack-of-all-temperatures” hypothesis predicts a trade-off between the breadth of the TPC and the maximal performance capacity; the “warmer is better” hypothesis suggests that low thermal optima will come with low absolute performances. Semi-aquatic organisms face the additional challenge of having to adjust their TPCs to two environments that are likely to differ in mean temperature and thermal variability. In this paper, we examine how parameters of the TPCs for maximal running and swimming speed have co-evolved in the semi-aquatic newt genus Triturus. We consider evolutionary relationships between the width and the height of the TPCs, the optimal temperatures and maximal performance. Phylogenetic comparative analyses reveal that in Triturus, swimming and running differ substantially in the (co-)variation of TPC parameters. Whereas evolutionary changes in the TPC for swimming primarily concern the shape of the curve (generalist versus specialist), most interspecific variation in running speed TPCs involves shifts in overall performance across temperatures.

Breeding site traits of European newts (Triturus macedonicus, Lissotriton vulgaris, and Mesotriton alpestris: Salamandridae) in the Montenegrin karst region

We recorded the occurrence of three European newt species - the smooth newt (Lissotriton vulgaris), the eastern alpine crested newt (Triturus macedonicus), and the alpine newt (Mesotriton alpestris) - in the Montenegrin karst, as well as their breeding site characteristics. In terms of long-lasting breeding site numbers and occupation rate, the most common species is the smooth newt, followed by the alpine newt and the crested newt. The examined water bodies with?out newts showed no significant differences of aquatic habitat characteristics compared to water bodies with newts. The factors that explained most of the observed variation in newt breeding site traits were the habitat category and habitat origin. The alpine newt primarily inhabits natural lakes, while the crested newt inhabits artificial breeding sites such as lithotelma and ubao. The smooth newt is less choosy and occurs in different types of natural and artificial habitats. The aquatic requirements of Montenegrin newt species do not differ substantially in many respects from requirements of the core species range populations.

Molecular DNA variation among Triturus vittatus vittatus (Urodela) from different breeding sites at the southern limit of its distribution

Molecular DNA variation among Triturus vittatus vittatus (striped newt) from different breeding sites at the southern limit of the species distribution (where environmental conditions are most extreme) was studied by the random amplification of polymorphic DNA (RAPD) method that has been found to be appropriate for other Triturus species. Altitudes of the localities ranged between 15-740 m a.s.l. Of the 20 primers employed, OPA-16 was the only one suitable for T. vittatus, revealing a differ - ent band pattern for different populations. Genetic similarity was calculated by band sharing, which demonstrated a high similarity among the Israeli populations.

Conservation of newt guilds in an agricultural landscape of Belgium: the importance of aquatic and terrestrial habitats

Amphibians are declining worldwide in response to local and global pressures. Pond-breeding species are particularly vulnerable to environmental change because they rely on two components of the landscape: aquatic and terrestrial habitats. Agricultural practices are changing rapidly at world and local scales. As a consequence, farm ponds and their surrounding terrestrial landscapes will probably be affected. 2. This study investigated the main habitat determinants for the occurrence of four species of newts (genus Triturus) inhabiting the Pays de Herve, a rural area in Belgium. Newt occurrence was determined for 258 ponds and the effect of habitat on distribution det erminants was evaluated using generalized linear models. 3. Newts were found in 42% of the ponds. Contrary to expectations, the distribution of newts was not positi- vely associated with a high density of ponds. However, a low occurrence of newts and the low water depth of many ponds suggest a low quality of habitats. Proximity to forest, deep water, and an absence of fish in ponds are factors that significantly favour newts, but terrestrial habitat requirements vary among species. 4. These results indicate the necessity of maintaining both forest and meadow patches in close proximity to ponds inhabited by newts, and of controlling fish introduction in those ponds. These findings stress the importance of conservation and management of terrestrial and aquatic habitats for maintaining amphibian diversity. Copyright © 2007 John Wiley & Sons, Ltd.