Neotropical frogs in the family Leptodactylidae frequently emit a loud scream upon being captured by predators, and the leptodactylid scream call was first classified as a distress call functioning to startle would-be predators into releasing prey frogs. Other authors, however, have suggested that scream calls function to warn nearby conspecifics of a predator threat (i.e., an alarm call) and/or to attract larger secondary predators to distract and/or predate the primary predator. In this study, we used a repeated-measures playback experiment to test whether Leptodactylus savagei (Smoky Jungle Frog) in Costa Rica responds to scream calls in ways consistent with the call functioning as an alarm. If scream calls emitted by individuals during predation events serve to warn nearby conspecifics of a predator threat, we predicted that scream calls would elicit elevated flight responses compared to when individuals are exposed to advertisement calls or control grey-noise treatments. We observed five primary behavioral responses: individuals flattened their bodies, faced their dens, fled into the dens, faced the audio treatment, and called back with a territorial vocalization. Behavioral responses differed by treatment: scream calls elicited a greater proportion of flight responses whereas advertisement calls caused individuals to demonstrate more interest in the call (particularly females). Our results suggest that L. savagei respond to screaming calls from conspecifics by fleeing in ways consistent with the call functioning as an alarm. Future studies are needed to test whether scream calls also function as a distress call and/or to attract secondary predators.

Understanding movement patterns and their biotic and abiotic correlates is crucial to effectively manage and conserve salamander populations of concern. Because information on Green Salamander (Aneides aeneus) movement patterns is limited, we tested several biological hypotheses about factors affecting their movements on the basis of data from 69 salamanders fluorescently tracked during spring of 2015 and 2016 in the Bankhead National Forest, northern Alabama. We found Green Salamanders primarily in rock crevices but also observed use of trees. Green Salamanders traveled through leaf litter but did not use it as a daily refuge. There was a significant difference between salamander body temperatures in daily refugia and ambient temperatures, indicating that refugia effectively buffer the species from ambient conditions. Green Salamanders moved an average of 4.98 m (95% confidence interval [CI] = 3.88–6.08) per night. Total distance traveled overnight increased with increasing body size for males but decreased with increasing size for females. Individual wandering ratios were affected by body size, with larger salamanders moving in more linear paths than smaller individuals. During nightly monitoring, 23% of salamanders did not leave their starting refuge or returned to it after a night of movement. Net distance movements showed selection of crevices averaging 1.94 m (95% CI = 0.90–2.99) from starting refuges. Our short-term movement study suggests that Green Salamanders use multiple neighboring refuges, follow complex paths in moving between them, and exhibit philopatry to those refuges.

Boreal Chorus Frogs (Pseudacris maculata) are widely distributed across North America; however, populations in parts of southeastern Canada and northeastern United States have been designated as either vulnerable or threatened because of human land use, and pressures from housing developments continue to jeopardize remnant populations found within fragmented habitats. A genetic characterization of Boreal Chorus Frogs sampled in Quebec and Ontario was conducted to help determine current levels of genetic variability, isolation, and to help identify important populations for conservation. The analysis involved 12 P. maculata-sampled locations using six microsatellite markers. Most exhibited discernible genetic differences, but some gene flow was still apparent among sites within and between three regions. We identified sampled locations with unique clustering results and little genetic similarity between neighboring sites. We propose that increased protection and monitoring of Boreal Chorus Frog populations, and establishing or expanding dispersal corridors among them, should be part of recovery planning.

Data deficiencies exist for ∼20–25% of amphibian and reptile species worldwide, typically excluding them from conservation consideration and funding opportunities. Current species status is often unknown at historic locations or previously unsurveyed areas. We present an iterative study to assess and optimize novel survey methods for a declining amphibian species (Boreal Toad, Anaxyrus boreas boreas) using a combination of methods. We found that if toads are present in a drainage, searching riparian areas multiple times during the active season is an efficient way of detecting the occurrence of previously unknown breeding populations. Once a breeding population has been located, traditional visual encounter surveys yield high probabilities of species detection for monitoring efforts (_vis ≈ 0.80). Supplementing streamside surveys when toads are not detected with other survey methods (e.g., environmental DNA [eDNA] samples) at suitable breeding locations can help confirm the species is absent, provided ≥10 eDNA samples are collected. Moreover, employing both visual surveys and eDNA samples can simultaneously yield distributional information on amphibian species and target pathogens, if pathogen presence is evaluated for all captured amphibian species and environmental samples are tested for both amphibian and pathogen DNA. Our iterative process of designing, testing, optimizing, and combining sampling methods to determine current species distribution should serve as a model for other rare amphibian and reptile species and provide managers better information with which to plan mitigation and conservation efforts.

Temperature tolerance can be a critical factor in determining amphibian species range over both latitudinal and elevational gradients; however, range limits across latitudes and elevations are not always congruent. For some mountaintop endemic and widespread salamanders in the Southern Appalachians, elevational distributions suggest the hypothesis that mountaintop species should be more cold tolerant, whereas latitudinal patterns are consistent with the hypothesis that widespread species should be more cold tolerant or tolerate a wider range of temperatures. We tested these hypotheses with year-round surveys of two mountaintop endemic species, Big Levels salamanders (Plethodon sherando) and Peaks of Otter salamanders (Plethodon hubrichti), at high- and low-elevation sites where they overlap with the widespread Eastern Redback salamander (Plethodon cinereus). We fit hierarchical Bayesian models to salamander surface counts across natural variation in soil temperature and moisture to compare temperatures that maximized surface counts (“peak activity temperature”) and the range of temperatures at which each species was active (“activity window”). We found that P. sherando and P. cinereus showed similar peak activity temperatures in areas of overlap, though P. sherando had a wider activity window as compared to P. cinereus. For P. hubrichti, we found a similar to somewhat higher peak activity temperature compared to P. cinereus, though P. cinereus had a wider activity window. We found no consistent differences in responses to soil moisture across species pairs. Our results suggest that elevational zonation in salamanders can result from a variety of processes and may not always reflect differences in relative temperature preferences.

When evolutionarily divergent lineages adjoin their geographic ranges after a period of isolation, myriad outcomes can occur, from population anastomosis to the evolution of reproductive isolation by way of reinforcement. Hybrid zones represent natural experiments that may indicate whether lineages will maintain their evolutionary independence. Here, we report on a hybrid zone in the Eastern Red-Backed Salamander, Plethodon cinereus, a highly abundant and wide-ranging terrestrial salamander found in the northeastern United States and in southeastern Canada. An earlier study identified six distinct mitochondrial clades across the range of P. cinereus. Populations of two of these clades were as close as 9.6 km apart in Lorain County, Ohio, USA. To investigate the nature of this contact zone, we sampled 316 individuals from 16 sites along a 53-km transect, and analyzed 10 microsatellite loci and one mitochondrial locus. We found a clinal transition for mtDNA haplotypes. In contrast, most studies of terrestrial plethodontid salamanders commonly exhibit sharp boundaries between mtDNA clades. Microsatellite markers, however, revealed little differentiation and weak population structure, suggesting the nuclear cline, if it exists, lies outside of our sampling region. Explanations for the discordance between the mitochondrial DNA and our microsatellite data include lineage sorting, male-biased dispersal, or historical introgression of mtDNA, among other possibilities. We compare our results with other studies of introgression in terrestrial salamanders, and discuss the causes of mitonuclear discordance.

Many oviparous species rely on hatching cues to ensure hatchlings maximize their survival, given the external environmental conditions. In nature, these cues are traditionally environmental (e.g., temperature) or social (e.g., communication between embryos). Examples of both are common throughout ectothermic taxa, particularly reptiles. In the present study, we explored the role of temperature in hatch timing in Snapping Turtles (Chelydra serpentina). We allowed embryos to incubate in wild nests for the majority of embryonic development, then isolated embryos in the lab, and maintained them at 24°C until they reached Yntema stage 25. At this developmental stage, external morphological differentiation is complete and yolk resorption begins. We then incubated embryos until pipping across a range of constant but biologically relevant temperatures (20, 23, 25, 28, or 30.5°C). To test whether thermal variance acts as a hatching cue, we also included a treatment in which temperature fluctuated diurnally around a stationary mean (25 ± 4°C). We found that the timing of egg pipping was not related to temperature treatment, thermal fluctuation, or sex of the embryo. Thus, contrary to traditional understanding, temperatures in the range studied do not affect the duration of the final embryonic stage in C. serpentina embryos, and a definitive hatching cue in this species is yet unknown.

The ecological consequences of impoundment construction on riparian systems throughout the U.S. Southwest has profoundly affected a variety of organisms, including many amphibians. To better understand the current extent of hybridization and changes in genetic composition over time in Bufo (Anaxyrus) woodhousii and Bufo microscaphus, we used microsatellite loci to evaluate 260 individuals representing 10 total populations constituting B. woodhousii, B. microscaphus, and putative hybrids along the Agua Fria River in Arizona during two time periods (1992–97 and 2009–10). Consistent with prior work with these two anurans documenting unidirectional replacement or genetic introgression, we predicted that microsatellites would provide evidence of directional introgression of B. woodhousii into B. microscaphus. The putative hybrid populations exhibited the highest number of alleles, and B. microscaphus exhibited the lowest number of alleles. Structure analysis indicated K = 2 as the best-fit population number for both time periods. All pairwise F-statistics were highly significant, corroborating differentiation among populations as inferred by structure analysis. The principal coordinates analysis demonstrated three distinct clusters of individuals that corresponded strongly with prior morphological and mitochondrial assignments within this region over both sampling periods. Our findings indicate that the genetic identity of B. microscaphus remains distinct from B. woodhousii and the hybrids, suggesting that the genetic structure of the corresponding populations has remained intact. Bufo woodhousii has not replaced B. microscaphus along the Agua Fria River beyond those habitats directly associated with impoundment construction.

Although the fossil record of pipoid frogs is more extensive than for other anuran clades, crown-group genera are poorly documented throughout the Cenozoic. We report an isolated neurocranium from the Nsungwe Formation (∼25 million years ago; Oligocene) in southwestern Tanzania, providing the earliest evidence for the genus Xenopus in sub-Saharan Africa. The specimen is well preserved, allowing us to use three-dimensional geometric morphometrics to compare the shape of this neurocranium to those of all extant species of Xenopus based on microcomputed tomography scans. Analyses revealed that this small fossil resembles diminutive extant species of Xenopus such as X. longipes. The fossil neurocranium preserves well-ossified tectum nasi and septum nasi, the latter separating large ovoid olfactory foramina, contributing to a more-ossified region surrounding the prootic foramen than observed in extant species of similar size. The Nsungwe Formation pipoid fossil contributes new information to the early biogeography and body-size diversification within the genus Xenopus.

We describe a new species of Adenomera from the Brazilian Atlantic Forest corresponding to one of the candidate species indicated in the published phylogeny of the genus (“sp. R”). The new species differs from all 18 congeners by the combination of small size, absence of toe discs, and the advertisement call composed of a single nonpulsed note with pronounced frequency upsweep. From the closest related and morphologically cryptic Adenomera araucaria, the new species is distinguished only by its nonpulsed advertisement call (multipulsed call in A. araucaria). The new species is distributed in the Serra do Tabuleiro mountain range and the Santa Catarina Island, as well as localities in between them in the eastern portion of the state Santa Catarina. This is the second Adenomera species endemic to the Atlantic Forest of eastern Santa Catarina in southern Brazil, sympatric to Adenomera engelsi and allopatric to the sibling A. araucaria.