Validation of the post-hoc method to estimate snout-vent length in the order Caudata Abstract. Amphibians are the most endangered class of vertebrates, with a high rate of decline recorded since the 20th century. Even activities related to the study of these animals for informing conservation actions, for instance by handling them to collect biometric individual parameters, can have negative effects on the amphibians’ health. A post-hoc method that estimates snout-vent length from dorsal photographs has been developed to reduce handling time and stress to individuals, providing additional advantages in precision and repeatability of measurements taken. However, at present, this methodology has been tested only on approximately 1% of the known salamanders, thereby limiting its broad application. Here, we tested this method on a diverse sample of Caudata that includes 25 species across 5 families and characterized by different morphologies. The correlation between predicted SVL (estimated from dorsal photographs) and observed SVL (measured directly from ventral photographs) values was assessed using Linear Mixed Models. The results showed a significant correlation between observed and predicted SVL, with an average and constant discrepancy of about 1.6 mm. When considering the increase of SVL, there was a slight tendency to underestimate SVLe in newts, plethodontids, and proteids. Estimation errors slightly increased with the SVL. The error increased in larger newts, while decreased in larger plethodontids. Our study highlighted the reliability and applicability of adopting this methodology for data collection in all Caudata species. Keywords. SVL, measure, post-hoc method, salamander, Urodela, photograph, dorsal.

Genomic insights into the Montseny brook newt (Calotriton arnoldi), a Critically Endangered glacial relict

Phylogeography of Rhabdias spp. (Nematoda: Rhabdiasidae) collected from Bufo species in Honshu, Shikoku, and Kyushu, Japan including possible cryptic species.

Abstract AimsIn many taxa, the latitudinal span of species' geographic ranges are positively correlated with median latitude (the Rapoport effect). This correlation is frequently explained as adaptation to contemporary climate; however, variability in post‐glacial range expansion among species could also explain this observation. We analyse geographic data for North American salamanders to test the potential causes of Rapoport effects.LocationTemperate North America.TaxonSalamanders (order Caudata).MethodsWe tested for a Rapoport effect by estimating correlations between the latitudinal midpoint and latitudinal range among species. Next, we manipulated species' latitudinal ranges by removing post‐glacial habitat and assessing the impact of species demonstrating post‐glacial range expansion in forming a Rapoport effect. We built ecological niche models for species found south of the Wisconsin Ice Sheet during the Last Glacial Maximum and transferred these models to post‐glacial areas. If dispersal is important in forming a Rapoport effect, then some species may tolerate northern climates but have not expanded northward as a result of variation in geographic access to post‐glacial habitats. We created binary ecological niche models by thresholding using the equal sensitivity and specificity value.ResultsWe recovered a Rapoport effect that was robust to the null models we tested. Analyses that manipulated ranges and species pools supported a role for variation in post‐glacial range expansion among species, especially for eastern North America. Results from transferring ecological niche models indicated that species have suitable habitat north of their range limit.Main conclusionsVariation in post‐glacial range expansion is important in shaping geographic range size clines among species in areas where climates changed rapidly, though we also found support for the climatic variability hypothesis. Post‐glacial colonization and range expansion likely plays an important role in forming latitudinal biodiversity gradients in northern taxa. While ecophysiology and biotic interactions have been emphasized as important contributors to diversity gradients, our study indicates that post‐glacial colonization also plays a key role in forming latitudinal gradients.

The North American newt genera Taricha and Notophthalmus (order Caudata) are well known for the combination of potent toxicity, aposematic coloration, and striking defense postures that protects these animals from predation. This suite of traits is centered around the neurotoxin tetrodotoxin, which causes paralysis and death in metazoans by disrupting the initiation and propagation of electrical signals in the nerves and muscles. Tetrodotoxin defends newts from predation across multiple life history stages and its role in generating arms-race coevolution between Taricha newts and garter snake (genus Thamnophis) predators is well studied. However, understanding the broader picture of chemical defenses in Taricha and Notophthalmus requires an expanded comprehension of the defensive chemical ecology of tetrodotoxin that includes possible coevolutionary interactions with insect egg predators, protection against parasites, as well as mimicry complexes associated with tetrodotoxin and aposematic coloration in both genera. Herein the authors review what is known about the structure, function, and pharmacology of tetrodotoxin to explore its evolution and chemical ecology in the North American newt. Focus is made specifically on the origin and possible biosynthesis of tetrodotoxin in these taxa as well as providing an expanded picture of the web of interactions that contribute to landscape level patterns of toxicity and defense in Taricha and Notophthalmus.

The data from 78 native species of reptiles and amphibians admitted to the Wildlife Rehabilitation Center of Parque Biológico de Gaia (Portugal) from 2009 to 2017 were revised to determine the main causes of morbidity and mortality. These data include four different orders: order Squamata (51.3%), order Testudinata (12.8%), order Anura (12.8%), and order Caudata (2.6%). 92.3% of the considered admittances were adults arriving during spring (41%) and autumn (29.5%). The main causes of admission to Rehabilitation Center were animals debilitated (12.8%) and injured (66.7%). Trauma was the major cause of mortality (78.2%). Unknown origin was the main cause of traumatic (71.8%) and non-traumatic (9.0%) death, followed by captivity related lesions (6.4%). These animals are excellent bioindicators of the health of the ecosystem and enable the identification of the main threats affecting them, especially those of anthropogenic origin. Studies of mortality on wild reptiles and amphibians are important to understand which the main threats and how human activity is affecting these populations.

Critical slowing down indicators in synchronous period-doubling for salamander flicker vision

Understanding the codon usage patterns of mitochondrial CO genes among Amphibians.

Over the last decades, the application of calcitic materials to soil to restore the vigor of Sugar Maple (Acer saccharum Marsh) trees has increased in northeastern North America. However, few studies have evaluated how this treatment affects other ecosystem components, especially over several years. In Sugar Maple stands, the Eastern Red-backed Salamander (Plethodon cinereus Green, 1818) is one of the most abundant vertebrates and an important terrestrial species for key ecological processes. Because the species commonly serves as an indicator of forest disturbances, it is important to know how anthropogenic disturbances, such as soil liming, might affect it. The goal of this study was to evaluate the medium-term (5-year) effects of liming on body condition in a wild population of P. cinereus in Quebec, Canada. Lime (CaCO3) was spread by helicopter on a declining Sugar Maple forest growing on an acidic and base-poor soil. The results of this study, combined with those of previous published works, show that liming has no short- or medium-term effects on the body condition of the Eastern Red-backed Salamander. This study adds to those on other species in Europe and northeastern North America that report that liming has no major effect on amphibians when it is used as a treatment to restore acidified forest ecosystems. This should help foresters decide whether or not liming treatments are compatible with conservation, ecological, and management objectives.

An aryl hydrocarbon receptor from the caecilian Gymnopis multiplicata suggests low dioxin affinity in the ancestor of all three amphibian orders

Whether hybridization generates or erodes species diversity has long been debated, but to date most studies have been conducted at small taxonomic scales. Salamanders (order Caudata) represent a taxonomic order in which hybridization plays a prevalent ecological and evolutionary role. We employed a recently developed model of trait-dependent diversification to test the hypothesis that hybridization impacts the diversification dynamics of species that are currently hybridizing. We find strong evidence supporting this hypothesis, showing that hybridizing salamander lineages have significantly greater net-diversification rates than non-hybridizing lineages. This pattern is driven by concurrently increased speciation rates and decreased extinction rates in hybridizing lineages. Our results support the hypothesis that hybridization can act as a generative force in macroevolutionary diversification.

Osteological structures are important biological features which provide valuable biological and ecological information. Luristan newt (Neurergus kaiseri), is an endemic salamander, inhabiting the southern part of Zagros Mountains of Iran. The current study was conducted to describe the osteological characteristics of the Luristan newt which might be important in understanding the evolutionary process of newt species. The skull of N. kaiseri has a dense structure, severely ossified elements and a low amount of cartilaginous elements, only in mobile facets. Vertebral number in the axial skeleton of the species equals 50. The cervical, abdominal and caudal parts of the vertebral column have two, 16 and 32 vertebrae, respectively. Each hand and foot consisted of four fingers, having three or four phalanxes. The metacarpal includes seven bones and the number of metatarsus bones is eight. Hands are connected to humur through ulnare and radius and then connected to scapulocoracoid. Each leg includes two bones (fibula and tibia) which are connected to femur. The head of the femur articulates with the acetabulum in the pelvic bone, while the distal part of the femur articulates with the tibia.

Under the current amphibian biodiversity crisis, common species provide an opportunity to measure population dynamics across a wide range of environmental conditions while examining the processes that determine abundance and structure geographical ranges. Studying species at their range limits also provides a window for understanding the dynamics expected in future environments under increasing climate change and human modification. We quantified patterns of seasonal activity, density and space use in the eastern red-backed salamander (<i>Plethodon cinereus</i>) near its southern range edge and compare the spatial ecology of this population to previous findings from the core of their range. This southern population shows the expected phenology of surface activity based on temperature limitations in warmer climates, yet maintains unexpectedly high densities and large home ranges during the active season. Our study suggests that ecological factors known to strongly affect amphibian populations (e.g. warm temperature and forest fragmentation) do not necessarily constrain this southern population. Our study highlights the utility of studying a common amphibian as a model system for investigating population processes in environments under strong selective pressure.

Inspired both by the literature reports and our previous fi ndings on the question if a seasonal cycle alone, consisting of temperature and photoperiod variations, might impact on or activate natural proliferative fl uctuations or unmask a latent spontaneous proliferative power in adult brain of poikilothermal Anamnia (fresh water, earth-dwelling) and Amniota (terrestrial), consequently allowing for encephalic reparative and even regenerative potentialities, an investigation has been carried on in normal adult brain of Triturus carnifex caught in nature in spring, summer, autumn. Cells immunostained for PCNA, i.e. cycling cells, were found scattered (“matrix cells”) in the olfactory territories, where they appeared scarce in spring, more frequent in summer, noticeable in autumn; also, immunostained cells were found clustered in “matrix areas”, also named zonae germinativae dorsales and ventrales, in the telencephalic hemispheres: few clusters in spring, an intermediate condition in summer, frequent cell groups in autumn. These results reveal an increasing trend in proliferation from spring, through summer, to autumn. This scenario was appreciable in the forebrain, mainly in the olfactory and telencephalic districts, which is the typical site of stem cells. Signs of potential proliferative activity are well ppreciable in the urodele Amphibians, which are the best provided among vertebrates with reparative and regenerative power and possess the richest endowment of dormant cells susceptible to be recruited to proliferation.

Actuarial senescence has been viewed for a long time as an inevitable and uniform process. However, the work on senescence has mainly focused on endotherms with deterministic growth and low regeneration capacity during the adult stage, leading to a strong taxonomic bias in the study of ageing. Recent studies have highlighted that senescence could indeed display highly variable trajectories that correlate with species life-history traits. Slow life histories and indeterminate growth seem to be associated with weak and late senescence. Furthermore, high regenerative abilities could lead to negligible senescence in ectotherms. However, demographic data for species that would allow testing of these hypotheses are scarce. Here, we investigated senescence patterns in ‘true salamanders’ from the Western Palearctic. Our results showed that salamanders have slow life histories and that they experience negligible senescence. This pattern was consistent at both intra- and interspecific levels, suggesting that the absence of senescence may be a phylogenetically conserved trait. The regenerative capacities of salamanders, in combination with other physiological and developmental features such as an indeterminate growth and a low metabolic rate, likely explain why these small ectotherms have lifespans similar to that of large endotherms and, in contrast with most amniotes, undergo negligible senescence. Our study seriously challenges the idea that senescence is a ubiquitous phenomenon in the tree of life.

This project in it's current form is intended for reviewers of a manuscript. It will be updated if the manuscript is accepted for publication.

Numerous physiological and morphological adaptations were achieved during the transition to lungless respiration that accompanied evolutionary lung loss in plethodontid salamanders, including those that enable efficient gas exchange across extrapulmonary tissue. However, the molecular basis of these adaptations is unknown. Here, we show that lungless salamanders express in the larval integument and the adult buccopharynx—principal sites of respiratory gas exchange in these species—a novel paralogue of the gene surfactant-associated protein C (SFTPC), which is a critical component of pulmonary surfactant expressed exclusively in the lung in other vertebrates. The paralogous gene appears to be found only in salamanders, but, similar to SFTPC, in lunged salamanders it is expressed only in the lung. This heterotopic gene expression, combined with predictions from structural modelling and respiratory tissue ultrastructure, suggests that lungless salamanders may produce pulmonary surfactant-like secretions outside the lungs and that the novel paralogue of SFTPC might facilitate extrapulmonary respiration in the absence of lungs. Heterotopic expression of the SFTPC paralogue may have contributed to the remarkable evolutionary radiation of lungless salamanders, which account for more than two thirds of urodele species alive today.

The sequence of the salamander

This lab introduces students to species concepts and basic computer-based tree-building methods using published nuclear and mitochondrial sequence data for Plethodon salamanders.

Collecting data on how populations respond to environmental change requires accurate estimates of population sizes. This activity explores one method for estimating population sizes across three different localities.