Notophthalmus Viridescens Research Articles

Functional trade-offs in the aquatic feeding performance of salamanders

During aquatic feeding salamanders use the hyobranchial apparatus to capture prey. The hyobranchial apparatus depresses the floor of the mouth, effectively expanding the oropharyngeal cavity and generating suction. Within the family Salamandridae, there is a wide range of ecological diversity, with salamanders being terrestrial, semi-aquatic, or aquatic as adults. The purpose of this research was to quantify the diverse morphology and suction feeding performance of aquatically feeding salamandrids. We hypothesized that a more robust hyobranchial apparatus morphology would yield increased aquatic feeding performance. When compared to semi-aquatic newts, the fully aquatic species Paramesotriton labiatus had greater mineralization of the hyobranchial apparatus, as well as relatively more narrow basibranchial and wider ceratobranchial I+II complexes. These morphological differences coincide with greater aquatic feeding performance. Kinematics from high-speed videography revealed that maximum mouth opening velocity and acceleration were approximately two and five times greater, respectively, in Paramesotriton, and hyobranchial depression acceleration was found to be approximately three times greater than in the semi-aquatic species Pleurodeles waltl, Notophthalmus viridescens, Triturus dobrogicus, and Cynops cyanurus. Using digital particle image velocimetry, peak and average fluid velocity generated in Paramesotriton during suction feeding events were found to be 0.5ms−1 and 0.2ms−1, respectively, doubling that of all semi-aquatic species. These findings reveal that specialized morphology increases aquatic feeding performance in a fully aquatic newt.

Dominance-function relationships in the amphibian skin microbiome.

Some amphibian skin bacteria inhibit growth of a fungal amphibian pathogen, Batrachochytrium dendrobatidis (Bd), but it is unclear how dominant these anti-Bd bacteria are in skin communities. Using in vitro co-culture challenge assays, we quantified Bd inhibition by bacterial isolates collected from the skin of four amphibian species: bullfrogs, Eastern newts, spring peepers and American toads. The 16S rRNA sequences for each isolate were matched to culture-independent amplicon sequences from the same individuals to assess inhibitory function versus relative abundance. Dominant bacteria had higher Bd inhibition than rare bacteria in bullfrog and newt populations, in which Bd was prevalent (>25%). Dominant and rare bacteria did not differ in Bd inhibition in spring peeper and toad populations, in which Bd was absent or at low prevalence (<7%). In addition, over half of the relative abundance of cultured bacteria on bullfrogs and newts was comprised of inhibitory bacteria, while only 25% and 37% of the relative abundance was inhibitory on spring peepers and toads, respectively. These results suggest that the dominant members of the amphibian skin bacterial community may be functionally important in terms of disease-resistance, and that Bd prevalence and/or host species identity may impact the relative abundance and inhibitory properties of skin bacteria.

The influence of breeding phenology on the genetic structure of four pond-breeding salamanders.

Understanding metapopulation dynamics requires knowledge about local population dynamics and movement in both space and time. Most genetic metapopulation studies use one or two study species across the same landscape to infer population dynamics; however, using multiple co‐occurring species allows for testing of hypotheses related to different life history strategies. We used genetic data to study dispersal, as measured by gene flow, in three ambystomatid salamanders (Ambystoma annulatum, A. maculatum, and A. opacum) and the Central Newt (Notophthalmus viridescens louisianensis) on the same landscape in Missouri, USA. While all four salamander species are forest dependent organisms that require fishless ponds to reproduce, they differ in breeding phenology and spatial distribution on the landscape. We use these differences in life history and distribution to address the following questions: (1) Are there species‐level differences in the observed patterns of genetic diversity and genetic structure? and (2) Is dispersal influenced by landscape resistance? We detected two genetic clusters in A. annulatum and A. opacum on our landscape; both species breed in the fall and larvae overwinter in ponds. In contrast, no structure was evident in A. maculatum and N. v. louisianensis, species that breed during the spring. Tests for isolation by distance were significant for the three ambystomatids but not for N. v. louisianensis. Landscape resistance also contributed to genetic differentiation for all four species. Our results suggest species‐level differences in dispersal ability and breeding phenology are driving observed patterns of genetic differentiation. From an evolutionary standpoint, the observed differences in dispersal distances and genetic structure between fall breeding and spring breeding species may be a result of the trade‐off between larval period length and size at metamorphosis which in turn may influence the long‐term viability of the metapopulation. Thus, it is important to consider life history differences among closely related and ecologically similar species when making management decisions.

Tetrodotoxin in Asian newts (Salamandridae)

Tetrodotoxin (TTX) and its analogues occur in a wide range of marine animals but also in terrestrial vertebrates such as frogs, toads and newts. Despite numerous studies on TTX in New World newts (Notophthalmus viridescens, Taricha spp.), few data only exist for Asian newts. Methanolic extracts of newts from China (Cynops orientalis, Pachytriton labiatus, Paramesotriton chinensis), Vietnam (Paramesotriton deloustali, P. guangxiensis), and Laos (Laotriton laoensis) were analyzed by liquid-chromatography-fluorescent detection (LC-FLD) and mass-spectrometry (LC-MS). In all species, variable amounts of TTX were detected, in most specimens also TTX-analogues like 6-epiTTX, in C. orientalis 11-oxoTTX, confirming the presence of these toxins in modern Asian newts.

The impacts of overwintered green frog larvae on wood frog embryo mortality under a wetter climate

Abstract For many species, the distribution and quantity of habitat is likely to be altered under climate change scenarios. Globally, temperatures are expected to increase, but changes in precipitation will be variable with some locations expected to receive more and other locations to receive less. The amount and timing of precipitation has a strong influence on wetland hydroperiod, which is a critical factor in determining wetland use by species of pond‐breeding amphibians. Past research has focused on the direct effects of reductions in precipitation and shorter hydroperiods, such as larvae desiccation, but little attention has been given to the indirect consequences of increased precipitation and longer hydroperiods, such as changes in predation pressure. We used wood frogs (Lithobates sylvaticus), a species that typically breeds in ephemeral (temporary) wetlands, to test the hypothesis that increased precipitation and permanent wetlands would indirectly increase mortality in wood frog embryos through increases in the density of embryo predators, second‐year green frog larvae (Lithobates clamitans), limnephilid and phryganeid caddisfly larvae and red‐spotted newts (Notophthalmus viridescens). We conducted translocation experiments in 2014 and 2015. We monitored wood frog embryo hatch success and mortality from predation using open (predator access) and closed (predators excluded) cages in 16 wetlands in each year. We observed no difference in embryo hatch success between ephemeral and permanent wetlands, with water temperature, not pH, affecting hatch rates. Wood frog embryos in permanent wetlands with overwintered second‐year green frog larvae had higher mortality from predation (0.80, 95% confidence intervals 0.65–0.91) than permanent wetlands (0.42, CI 0.26–0.60) and ephemeral wetlands (0.37, CI 0.31–0.45) that lacked predatory green frog larvae. Embryo mortality from predation increased with increasing green frog larvae density. Regression models showed that ponds with larvae densities &gt;2.5 larvae m−2 resulted in 90% embryo mortality. Caddisfly larvae and red‐spotted newt density had no effect, and pond water temperature had a weak negative effect on embryo mortality from predation. Under a wetter and warmer climate, springtime occupancy of predatory green frog larvae is likely to increase, resulting in a reduction in the amount of suitable wood frog breeding habitat. Our research suggests that indirect effects of climate change mediated through biotic interactions may play a critical role in the distribution of ephemeral wetland species.

The association between male-biased sex ratio and indicators of stress in red-spotted newts

In populations with a male-biased operational sex ratio, coercive mating by males can have fitness consequences for females. One component of reduced fitness for females in populations with a male-biased OSR may be greater activation of the stress response, resulting in higher corticosterone release rates (CORT; a glucocorticoid stress hormone in amphibians). We test the hypothesis that a male-biased sex ratio affects female activity and release rates of CORT and testosterone (T) in male and female red-spotted newts (Notophthalmus viridescens). First, we evaluated if chemical cues from a male-biased sex ratio affect activity and CORT release rates in females. We predicted that females exposed to chemical cues of three males would be less active and have higher CORT release rates than those exposed to chemical cues of one male. Second, we measured CORT release rates of red-spotted newts in field enclosures with either a male-biased or a female-biased sex ratio. We predicted that females in the male-biased treatment would have higher CORT and T release rates than those in a female-biased treatment, owing to higher levels of male harassment. We also predicted that males would have higher CORT and T release rates in male-biased treatments due to higher levels of male-male competition. Females were not less active in response to chemical cues from more males over fewer males, but there was a positive relationship between female activity and CORT when they were exposed to the cues of three males. We also found that females, but not males, in the male-biased sex ratio treatment had higher CORT and T release rates than those in the female-biased treatment. Our results support the hypothesis that a male-biased sex ratio leads to a higher stress response, which may underlie the observed decrease in immune function and body condition in previous work exposing female red-spotted newts to a male-biased sex ratio. This study furthers our understanding of the mechanistic basis for costs associated with a male-biased sex ratio in a pond-breeding amphibian.

The influence of environmental factors on pond activity of aquatic red-spotted newts Notophthalmus viridescens

ABSTRACTMany important components of animal behavior, growth, and reproduction are tightly linked to environmental conditions, particularly for ectothermic freshwater organisms. For amphibian species, factors such as temperature and rainfall can be physiologically limiting and alter activity levels. The effects of environmental conditions on terrestrial amphibian movement have been well characterized, but less is known about the importance of these factors in aquatic habitats. Here we investigate the impact of temperature and rainfall on the activity of a pond-dwelling amphibian using capture patterns of aquatic adult red-spotted newts (Notophthalmus viridescens). Data on newt captures, air temperature, and rainfall were collected for 6 years (2009, 2011, 2013–2016) during the winter breeding season at a wetland in the Piedmont region of North Carolina, USA. In 2016, we collected more detailed data on the size and sex of captured newts, as well as recording water temperature. Overall, temperature played a significant role in determining newt activity, while rainfall had little effect. As expected, and consistent with findings on amphibian activity in terrestrial systems, newt captures increased with increasing air temperature. During the 2016 breeding season we found sex-based changes in activity in response to temperature, with a higher proportion of males captured during warmer temperatures and a reduction in the male capture bias during colder temperatures. We found no evidence of size-based shifts in activity in response to temperature. This study increases our knowledge of amphibian responses to temperature while in aquatic habitats. Although the duration of time spent in aquatic habitats can be highly variable between species, these breeding locations are critical for the persistence of populations and activity levels, and reproductive success in these wetlands can be highly impacted by future changes in environmental conditions.

Middle of the road: enhanced habitat for salamanders on unused logging roads

Context Amphibians are particularly susceptible to the effects of habitat loss and fragmentation. The construction and use of roads is among the most common sources of habitat fragmentation and can lead to serious population declines. Unused resource access roads, such as those formerly used for logging, can still negatively impact salamanders and reduce habitat quality through edge effects. Unfortunately, habitat rehabilitation and enhancement is rarely attempted on unused forest roads. Aims Our aim was to elaborate on a previous study that tested several types of woody debris to mitigate the negative impacts of forest roads by creating a novel habitat on an unused forest road in Algonquin Provincial Park. Here we focus solely on the use of large, squared timbers and their use by salamanders. Methods We tested the application of coarse woody debris (CWD) to the surface of an unused forest road. CWD were sampled for salamanders seven times during the 2011 field season. Local climatic variables were tested against salamander captures, and CWD size preferences and patterns of salamander aggregation under CWD were assessed. Key results We observed five salamander species and 415 individuals under timbers in the 2011 field season. Larger timbers (&gt;1m3) were preferred by all species observed and a significant proportion of animals were found in groups of two or more under larger timbers. High ambient temperature and low relative humidity negatively affected the number and species composition observed under timbers, suggesting that the efficiency of CWD as a survey method and enhanced habitat is season dependent. Implications Large timbers placed on unused forest roads may provide suitable refuges for migrating or dispersing forest salamanders while they attempt to cross the road. The tendency of salamanders to aggregate under CWD allows individual red efts to reduce water loss; however, red-backed salamanders are territorial and may drive off conspecifics. The use of large CWD may be an effective and low-cost method to rehabilitate unused forest roads and can be used to promote habitat connectivity for salamanders in targeted habitats, such as near wetlands, or for other species of concern.

Absence of visual discrimination by female eastern newts during mate selection

Male eastern newts (Notophthalmus viridescens) exhibit tremendous variation in several characteristics, including the number of dorsal spots, the brightness of those spots, tail depth and tail length. These traits could be used by females for mate selection decisions. We conducted two experiments to determine whether females use visual signals to assess these characteristics in their mate selection decisions by simultaneously exposing a female to males of opposing characteristics. We observed female preference for the number of spots on a male’s dorsum, the brightness of male dorsal spots, male body mass, and male tail depth and length. We then recorded the amount of time the female spent in a preference zone adjacent to each of the males. Female newts did not show a significant preference for any of the characteristics observed, spending roughly equal amounts of time in both preference zones. These results, combined with the results of several previous studies, suggest that female eastern newts do not use visual signals to assess these traits in their mate selection decisions. Given that most of these traits are sexually dimorphic, this is likely due to the reproductive advantage created by the intense male–male competition present and their amplexus-based mating system.

The Role of Prey in Microgeographic Variation in Red-Spotted Newt (Notophthalmus viridescens viridescens) Head Width

Abstract For gape-limited predators, investment in larger heads should occur when larger prey items are more profitable or are the only prey option available. This may result in evolutionary or within-lifetime (plastic) increases in gape size in animals exposed to larger prey. This phenomenon has been well documented in larval but not adult caudates (salamanders and newts). We report here evidence of greater gape size in populations of a newt that co-occur with energetically profitable, large prey. We collected morphological data from populations of Red-Spotted Newts (Notophthalmus viridescens viridescens) that occupied nearby ponds that varied in the presence of eggs and tadpoles of Wood Frogs (Lithobates sylvaticus). Newts were larger in ponds occupied by Wood Frogs, suggesting a potential energetic advantage to this prey. Newts syntopic with Wood Frogs had relatively wider heads, which we interpret as a potential adaptation for consuming seasonally abundant Wood Frog eggs and tadpoles. Male newts had w...

Genital and Pelvic Kidney Renal Corpuscles of the Red-spotted Newt,Notophthalmus viridescens(Amphibia, Urodela, Salamandridae)

Salamanders possess a bipartite kidney: a caudal portion contains nephrons that primarily function in urine formation (pelvic kidney nephrons) and a cranial portion where nephrons also serve as sperm conduits (genital kidney nephrons). Nephrons of these two kidney regions were examined microscopically in Notophthalmus viridescens. No microstructural differences were observed between the filtration barriers of renal corpuscles from pelvic and genital kidney nephrons. However, pelvic kidney renal corpuscles were significantly larger than genital kidney renal corpuscles and possessed a much more developed, and vascularized, glomerular structure. Furthermore, whereas filtrate was easily observed in the urinary space of pelvic kidney renal corpuscles, the urinary space of genital kidney renal corpuscles did not bind with stains used for examination with transmission electron microscopy. This finding corresponds with the previous lack of filtrate observed in the proximal tubules of genital kidney nephrons in comparison to copious filtrate in pelvic kidney proximal tubules. These results may indicate a lack of urine forming function in the genital kidney nephrons.

A linkage map for the Newt Notophthalmus viridescens: Insights in vertebrate genome and chromosome evolution

Genetic linkage maps are fundamental resources that enable diverse genetic and genomic approaches, including quantitative trait locus (QTL) analyses and comparative studies of genome evolution. It is straightforward to build linkage maps for species that are amenable to laboratory culture and genetic crossing designs, and that have relatively small genomes and few chromosomes. It is more difficult to generate linkage maps for species that do not meet these criteria. Here, we introduce a method to rapidly build linkage maps for salamanders, which are known for their enormous genome sizes. As proof of principle, we developed a linkage map with thousands of molecular markers (N=2349) for the Eastern newt (Notophthalmus viridescens). The map contains 12 linkage groups (152.3–934.7cM), only one more than the number of chromosome pairs. Importantly, this map was generated using RNA isolated from a single wild caught female and her 28 offspring. We used the map to reveal chromosome-scale conservation of synteny among N. viridescens, A. mexicanum (Urodela), and chicken (Amniota), and to identify large conserved segments between N. viridescens and Xenopus tropicalis (Anura). We also show that met1, a major effect QTL that regulates the expression of alternate metamorphic and paedomorphic modes of development in Ambystoma, associates with a chromosomal fusion that is not found in the N. viridescens map. Our results shed new light on the ancestral amphibian karyotype and reveal specific fusion and translocation events that shaped the genomes of three amphibian model taxa. The ability to rapidly build linkage maps for large salamander genomes will enable genetic and genomic analyses within this important vertebrate group, and more generally, empower comparative studies of vertebrate biology and evolution.

Physical wetland characteristics influence amphibian community composition differently in constructed wetlands and natural wetlands

Wetlands provide critical habitat for a diverse group of organisms and provide important ecosystem services. Despite this, most natural wetlands have been lost to anthropogenic activities, and as a result, wetland construction is common mitigation practice. Therefore, examination of constructed wetland viability in replacing the function of lost wetlands is vital. Our primary objectives were to compare amphibian communities of shallow and deep constructed wetlands to natural wetlands and to identify which wetland characteristics affect species composition. All wetlands were hydrologically isolated and fishless; natural wetlands had an ephemeral hydrology, and constructed wetland hydrology varied from ephemeral to permanent. Overall, constructed wetlands did not sufficiently replicate natural wetlands with respect to the amphibian community. However, two of our constructed wetlands had a drying period and exhibited communities more similar to natural wetlands. Hydroperiod and canopy closure were indicators of amphibian community composition. Many species observed in natural wetlands were rare in shallow constructed and absent in deep constructed wetlands. Additionally, dominant predator species (primarily Lithobates catesbeianus, Lithobates clamitans, and Notophthalmus viridescens) associated with permanent water were more abundant in constructed wetlands. Water depth, pH, and emergent vegetation were lower in natural wetlands. These data influenced land managers to revise construction methods and to renovate deep constructed wetlands by creating gradual slopes, decreasing maximum depth to 20cm or less, maintaining canopy cover, and decreasing soil compaction to attempt replication of natural wetland hydrology.

Further Characterization of Anuran‐Like Aquaporins in the Urinary Bladder of Urodeles, Notopthalmus viridescens and Cynops pyrrhogaster

Recent Bayesian analysis of tetrapod aquaporin gene clusters by Finn et al (PLOS1, November 26, 2014) suggests anuran‐specific aquaporins that mediate water transport across the ventral skin (AQPa2S) and urinary bladder (AQPa2U) are more closely related to AQP6 found in mammals and reptiles. Furthermore, AQP6/a2 aquaporins are syntenic with AQP5. We used RT‐PCR to show both AQP6/a2U and AQP5 homologs are expressed in the urinary bladder of the newts, Notophthalmus viridescens (nv) and Cynops pyrrhogaster (cp). Full length amino acid sequences showed 72% and 71% identity between AQP6/a2U of nv and anuran species Hyla japonica and Xenopus tropicalis (xt). Amino acid identity of AQP5 between nv and cp was 95% while identity between both urodeles and xt was 69%–70%.Consensus phosphorylation sites for PKA were identified for AQP6/a2U and AQP5 for both nv and cp. AQP5 could be immunolocalized in the apical membrane of bladder epithelial cells in rehydrating newts. These results indicate an absorptive role for AQP5 in the urodele urinary bladder and suggest that this role may originate in the ancestor of urodeles and anurans.Support or Funding InformationSupported by a Grant‐in‐Aid for Scientific Research (26440165) from the Ministry of Education, Culture, Sports, Science and Technology of Japan.

The praying mantis (Mantodea) as predator of the poisonous red-spotted newt Notophthalmus viridescens (Amphibia: Urodela: Salamandridae)

A Chinese praying mantis, Tenodera sinensis, was observed feeding on a living red-spotted newt, Notophthalmus viridescens. Specimens of that newt’s population are known to contain high concentrations of tetrodotoxin (TTX), a specific blocker of voltage-gated sodium channels. After experimental oral administration of a TTX-solution (1 mg/ml) to adult specimens of four mantis species, all survived high TTX concentrations (up to 30.8 μg/g body mass) as revealed by analysis of their body extracts, but they are rapidly killed by intra-abdominal injection of 1 μg TTX. The toxin was found to be gradually excreted with faeces. As demonstrated by monoclonal antibody-based immunohistochemical technique, TTX does not penetrate the mid-gut membrane, since it was localized only in the gut lumen, but not in the epithelial cells. This prevents the toxin to reach its target, the sodium channels of the insect’s nervous system, and enables the mantids to feed on toxic prey without risking poisoning.

Potential Influence of Salamanders and Coarse Woody Debris on the Distribution ofDryopteris intermediain a Hardwood Forest

Abstract Dryopteris intermedia (Common Wood Fern) is more associated with coarse woody debris (CWD) than the surrounding forest floor. Along with microsite-based establishment benefits, dispersal vectors may facilitate this distribution. Some salamanders are associated with CWD and may serve as dispersal agents for spores of the Common Wood Fern. In a deciduous forest of south-central New York State, we assessed the ability of Plethodon cinereus (Red-backed Salamander) and Notophthalmus viridescens (Eastern Newt) to pick up and transport spores and sori fragments from the dorsal side of the frond, and rinsed salamanders to collect and germinate any viable spores from their bodies. We also measured the moisture content of soft CWD, soil beneath hard CWD, and background soil. Both salamander species picked up reproductive components of Common Wood Fern. Wild-caught salamanders of both species had viable spores on their bodies. Soft CWD held more moisture than soil beneath hard CWD and the forest-floor soil....

Both novelty and conspicuousness influence selection by mammalian predators on the colour pattern ofPlethodon cinereus(Urodela: Plethodontidae)

Predators influence the evolution of colour pattern in prey species, yet how these selective forces might differ among predators is rarely considered. In particular, prey colour patterns that indicate unpalatability to some predator species may not carry the same signal for other predators. We test several hypotheses of selection on patterning between mammal predators and the polymorphic salamander Plethodon cinereus, which, under an avian visual system appears as a mimic of the toxic newt Notophthalmus viridescens. We fit each hypothesis against field observations of mammalian attacks on salamander clay replicas. We then develop a novel analytical procedure that enables the combination of multiple non-exclusive models in a likelihood framework. We find that mammals do not follow any single hypothesis proposed, including the hypothesis of mimicry. Instead, mammals in this system use visual cues while foraging to avoid unfamiliar, novel prey and attack conspicuous prey. We propose that mammals may help to maintain colour pattern polymorphism within populations of P. cinereus by avoiding novel, unfamiliar colour morphs. Additionally, selective pressures from multiple predators and variation in predator communities among sites may contribute to the maintenance of colour polymorphism within and among localities in this salamander species.

Disease dynamics of red-spotted newts and their anuran prey in a montane pond community.

Long-term monitoring of amphibians is needed to clarify population-level effects of ranaviruses (Rv) and the fungal pathogen Batrachochytrium dendrobatidis (Bd). We investigated disease dynamics of co-occurring amphibian species and potential demographic consequences of Rv and Bd infections at a montane site in the Southern Appalachians, Georgia, USA. Our 3-yr study was unique in combining disease surveillance with intensive population monitoring at a site where both pathogens are present. We detected sub-clinical Bd infections in larval and adult red-spotted newts Notophthalmus viridescens viridescens, but found no effect of Bd on body condition of adult newts. Bd infections also occurred in larvae of 5 anuran species that bred in our fishless study pond, and we detected co-infections with Bd and Rv in adult newts and larval green frogs Lithobates clamitans. However, all mortality and clinical signs in adult newts and larval anurans were most consistent with ranaviral disease, including a die-off of larval wood frogs Lithobates sylvaticus in small fish ponds located near our main study pond. During 2 yr of drift fence monitoring, we documented high juvenile production in newts, green frogs and American bullfrogs L. catesbeianus, but saw no evidence of juvenile recruitment in wood frogs. Larvae of this susceptible species may have suffered high mortality in the presence of both Rv and predators. Our findings were generally consistent with results of Rv-exposure experiments and support the purported role of red-spotted newts, green frogs, and American bullfrogs as common reservoirs for Bd and/or Rv in permanent and semi-permanent wetlands.

Species Interactions in Constructed Wetlands Result in Population Sinks for Wood Frogs (Lithobates sylvaticus) while Benefitting Eastern Newts (Notophthalmus viridescens)

Wetland construction has been used as a tool to mitigate wetland loss, but constructed wetlands might not provide the same functions as natural wetlands. Hundreds of long-hydroperiod wetlands have been constructed within the Daniel Boone National Forest, Kentucky, in a ridge-top ecosystem where natural wetlands dry annually (i.e., have short hydroperiods). The constructed wetlands have been colonized by several amphibian species not historically associated with this ecosystem and that could have negative impacts on native amphibian species. We compared wood frog (Lithobates sylvaticus) reproductive success at constructed and natural wetlands and benefits of wood frog presence in constructed wetlands to eastern newts (Notophthalmus viridescens). Wood frog reproductive success was zero when eggs were laid in constructed wetlands: 7–70 % of eggs were consumed and no wood frog larvae were found. Eastern newts, present at all constructed wetlands, benefited from wood frog presence, i.e., newts in constructed wetlands with wood frog eggs had higher body condition than newts in natural wetlands. Wetland construction techniques should be altered so their hydrology mimics that of natural wetlands to support historically occurring species. Understanding the influence of species interactions, as habitat loss and modification increase, will continue to be critical for amphibian conservation.

Only fear the fatal foe: predation risk assessment by eastern newts (Notophthalmus viridescens) in response to common snapping turtles and other potential predators

Many organisms utilize toxic or noxious compounds as a means of deterring predation. Eastern newts (Notopthalmus viridescens), along with other species in the family Salamandridae, possess a potent neurotoxin called tetrodotoxin (TTX). Although TTX can serve as an effective antipredator mechanism in species of newts with high concentrations (e.g., Taricha), eastern newts have relatively low levels of toxicity in comparison to those species, and it may not serve as an effective antipredator mechanism against all threats. In this case, they may benefit rather by utilizing behavioral changes to avoid initial contact with predators. We tested for predator-avoidance behavior in newts by exposing individuals to kairomones from various predators. We recorded activity patterns of newts when they were exposed to cues from potential predators including bullfrogs (Lithobates catesbeiana), water snakes (Nerodia sipedon) and snapping turtles (Chelydra serpentina), as well as a non-predator (bullfrog tadpoles), and a control (deionized water). Newts reduced activity when exposed to snapping turtle stimuli, but did not change activity when exposed to any other chemical cues. We verified that newts interact with this predator by trapping snapping turtles found in ponds from which newts were collected. Finally, we used turtles caught during this sampling to test whether they are an actual predator of newts and whether newts shift microhabitat use when exposed to this predator. In each replicate, turtles consumed newts, and newts spatially avoided the snapping turtle, relative to a control. The results of these experiments indicate newts rely on predator-avoidance behavior to reduce the probability of being consumed by snapping turtles, but do not reduce activity in response to other potential predators that may only consume them rarely.