Distribution of the alpine newt Ichthyosaura alpestris in Great Britain updated using social media

The alpine newt (Ichthyosaura alpestris) is an alien species in Great Britain. Using location information derived from photographs posted on social media we have updated its known distribution, validated previously unconfirmed populations, and present an updated distribution map. Comparison of the records collected from social media with those in the National Biodiversity Network Atlas indicates eleven new confirmed populations, although three of these had previously been shown as unconfirmed records in the NBN Atlas. The new records have been deposited with NBN.

Use of a high resolution magnetic map by a short distance migrant, the alpine newt (Ichthyosaura alpestris)?

Newts can use spatial variation in the magnetic field (MF) to derive geographic position, but it is unclear how they detect the ‘spatial signal’ which, over the distances that newts move in a day, is an order of magnitude lower than temporal variation in the MF. Newts take map readings using their light-dependent magnetic compass to align a magnetite-based ‘map detector’ relative to the MF. Time-of-day, location, and light exposure (required by the magnetic compass) were varied to determine when newts obtain map information. Newts were displaced from breeding ponds without access to route-based cues to sites where they were held and/or tested under diffuse natural illumination. We found that: (1) newts held overnight at the testing site under diffuse illumination exhibited accurate homing orientation, but not if transported to the testing site on the day of testing, (2) newts held overnight under diffuse lighting at a ‘false testing site’ and then tested at a site located in a different direction from their home pond, oriented in the home direction from the holding site, not from the site where they were tested, (3) newts held overnight in total darkness (except for light exposure for specific periods) only exhibited homing orientation the following day if exposed to diffuse illumination during the preceding evening twilight in the ambient MF. These findings demonstrate that, to determine the home direction, newts require access to light and the ambient MF during evening twilight when temporal variation in the MF is minimal.

Mitochondrial DNA diversity of the alpine newt (Ichthyosaura alpestris) in the Carpathian Basin: evidence for multiple cryptic lineages associated with Pleistocene refugia

The phylogeography and molecular taxonomy of the Alpine newt, Ichthyosaura alpestris, has been intensively studied in the past. However, previous studies did not include a comprehensive sampling from the Carpathian Basin, possibly a key region in the evolution of the species. We used a 1251 bp long fragment of the mitochondrial genome to infer the species’ evolutionary history in central-eastern Europe by assigning isolated Carpathian Basin populations from 6 regions to previously defined mtDNA lineages. We also revised the morphology-based intraspecific taxonomy of the species in the light of new genetic data. Alpine newt populations from the Carpathian Basin represented two different mitochondrial lineages. The Mátra, Bükk and Zemplén Mts populations can be assigned to the Western lineage of the nominotypical subspecies. Bakony and Őrség populations showed high haplotype diversity and formed a separate clade within the Western lineage, suggesting that the Carpathian Basin might have provided cryptic refugia for Alpine newt populations in their cold-continental forest-steppe landscapes during the younger Pleistocene. Newts from Apuseni Mts were related to the Eastern lineage but formed a distinct clade within this lineage. Considering the morphological and genetic differentiation of the Bakony and Őrség populations, consistent with a long independent evolutionary history, we propose these populations be referred to as Ichthyosaura alpestris bakonyiensis (Dely, 1964). We provide a redescription of this poorly known subspecies.

Mass mortality of unknown etiology in alpine newts (Ichtyosaura alperstris veluchiensis) in an alpine lake in Greece

A mass mortality in alpine newts (Ichthyosaura alpestris veluchiensis) was observed in May/June 2013, in Drakolimni lake on Smolikas Mountain, Northwest Greece. 1300 alpine newts were found dead in two events. In 1998 a similar incident was recorded in the nearby lake of Timfi Mt. Newts of every stage and sex were affected, presenting incoordination and inability to float evenly. Ten animals were submitted for complete pathological examination. Field environmental measurements (water temperature, oxygen saturation, pH, conductance, nitric/phosphate concentration) and samples (water, snow, benthos) were collected for ecotoxicological and quality analysis. Necropsy, microbiology (parasitology, bacteriology, mycology), histopathology, molecular investigations (Ranavirus spp, Batrachochytridium dendrobatidis, Batrachochytridium salamandrivorans), quality and ecotoxicological examinations did not indicate a causative source for the mortality. To the author´s knowledge this is the biggest mortality of unknown etiology reported in free-living alpine newts in Europe.

Alpine Newts (Ichthyosaura alpestris) Avoid Habitats Previously Used by Parasite-Exposed Conspecifics

Many organisms avoid habitats posing risks of parasitism. Parasites are not generally conspicuous, however, which raises the question of what cues individuals use to detect parasitism risk. Here, we provide evidence in alpine newts (Ichthyosaura alpestris) that non-visual cues from parasite-exposed conspecifics inform habitat avoidance. Alpine newts breed in aquatic habitats and occasionally move among adjacent terrestrial habitat during breeding seasons. We completed experiments with newts whereby individuals had access to both habitats, and the aquatic habitats varied in prior occupancy by conspecifics with different histories of exposure to the parasitic skin fungus, Batrachochytrium dendrobatidis (Bd). Continuous filming of newt activity for 2 days provided little evidence that prior use of aquatic habitats by conspecifics, regardless of their Bd exposure history, immediately influenced newt habitat use. However, newts that encountered aquatic habitats used specifically by Bd-exposed conspecifics on day 1 spent less time aquatic on day 2, whereas other newts did not alter habitat use. Responses could have been elicited by cues generated by Bd stages on the conspecifics or, perhaps more likely, cues emitted by the conspecifics themselves. In either case, these observations suggest that newts use non-visual cues sourced from exposed conspecifics to detect Bd risk and that those cues cause newts to avoid aquatic habitats. Bd may therefore influence host behavior in early phases of interactions, and possibly before any contact with infectious stages is made, creating potential for non-consumptive effects.

Behavioural responses to chemical cues of predators differ between fire salamander larvae from two different habitats

Predation is one of the strongest selection pressures, forcing prey organisms to detect predators and to display various antipredator behaviours, such as refuge-use or decreased activity. To recognise predators, chemosensory cues play a pivotal role, particularly in aquatic ecosystems. However, it is less known whether the ability to use these cues to respond with adequate antipredator behaviour varies between individuals occupying different habitats that are dissimilar in predation risk. Using field experiments, we examined antipredator behaviour of larval fire salamanders (Salamandra salamandra) from two different habitats, ponds and streams. Among other differences, ponds and streams are inhabited by habitat-specific predators, such as alpine newts (Ichthyosaura alpestris) occurring in ponds. We exposed larvae from both habitats to either chemical cues from alpine newts or a blank control (tap water) and investigated potential differences in their behavioural responses in two experiments. Pond larvae, but not stream larvae, became significantly less active when faced with chemical cues from newts compared to those faced with a control stimulus. Moreover, larvae from both habitats tested in water containing chemical cues spent significantly less time outside a shelter than those in control water. Our results demonstrate that larval fire salamanders recognise predatory newts through kairomones and alter their behaviour accordingly. However, experience with predatory newts may not be necessary to differentiate kairomones from control water, but may be beneficial for larvae to further develop their antipredator behaviour, thus representing conformance to a niche.

Underwater sound production varies within not between species in sympatric newts

Sound production is a widespread phenomenon among animals. Effective sound use for mate or species recognition requires some acoustic differentiation at an individual or species level. Several species of caudate amphibians produce underwater sounds, but information about intra- and interspecific variation in their acoustic production is missing. We examined individual, sex, and species variation in underwater sound production in adults of two sympatric newt taxa, Ichthyosaura alpestris and Lissotriton vulgaris. Individual newts produced simple low- (peak frequency = 7–8 kHz) and mid-high frequency (14–17 kHz) clicks, which greatly overlap between sexes and species. Individual differences explained about 40–50% of total variation in sound parameters. These results provide foundations for further studies on the mechanisms and eco-evolutionary consequences of underwater acoustics in newts.