Search

Aposematic organisms rely on their conspicuous appearance to signal that they are defended and unpalatable. Such phenotypes are strongly tied to survival and reproduction. Aposematic colors and patterns are highly variable; however, the genetic, biochemical, and physiological mechanisms producing this conspicuous coloration remain largely unidentified. Here, we identify genes potentially affecting color variation in two color morphs of Ranitomeya imitator: the orange-banded Sauce and the redheaded Varadero morphs. We examine gene expression in black and orange skin patches from the Sauce morph and black and red skin patches from the Varadero morph. We identified genes differentially expressed between skin patches, including those that are involved in melanin synthesis (e.g. mlana, pmel, tyrp1), iridophore development (e.g. paics, ppat, ak1), pteridine synthesis (e.g. gch1, pax3-a, xdh), and carotenoid metabolism (e.g. dgat2, rbp1, scarb2). In addition, using weighted correlation network analysis, we identified the top 50 genes with high connectivity from the most significant network associated with gene expression differences between color morphs. Of these 50 genes, 13 were known to be related to color production (gch1, gmps, gpr143, impdh1, mc1r, pax3-a, pax7, ppat, rab27a, rlbp1, tfec, trpm1, xdh).

Reptiles and amphibians (herptiles) are some of the most endangered and threatened species on the planet and numerous conservation strategies are being implemented with the goal of ensuring species recovery. Little is known, however, about the gut microbiome of wild herptiles and how it relates to the health of these populations. Here, we report results from the gut microbiome characterization of both a broad survey of herptiles, and the correlation between the fungus Basidiobolus, and the bacterial community supported by a deeper, more intensive sampling of Plethodon glutinosus, known as slimy salamanders. We demonstrate that bacterial communities sampled from frogs, lizards, and salamanders are structured by the host taxonomy and that Basidiobolus is a common and natural component of these wild gut microbiomes. Intensive sampling of multiple hosts across the ecoregions of Tennessee revealed that geography and host:geography interactions are strong predictors of distinct Basidiobolus operational taxonomic units present within a given host. Co-occurrence analyses of Basidiobolus and bacterial community diversity support a correlation and interaction between Basidiobolus and bacteria, suggesting that Basidiobolus may play a role in structuring the bacterial community. We further the hypothesis that this interaction is advanced by unique specialized metabolism originating from horizontal gene transfer from bacteria to Basidiobolus and demonstrate that Basidiobolus is capable of producing a diversity of specialized metabolites including small cyclic peptides.IMPORTANCEThis work significantly advances our understanding of biodiversity and microbial interactions in herptile microbiomes, the role that fungi play as a structural and functional members of herptile gut microbiomes, and the chemical functions that structure microbiome phenotypes. We also provide an important observational system of how the gut microbiome represents a unique environment that selects for novel metabolic functions through horizontal gene transfer between fungi and bacteria. Such studies are needed to better understand the complexity of gut microbiomes in nature and will inform conservation strategies for threatened species of herpetofauna.

The North Campus Open Space (NCOS) restoration project has created more than 40 acres of estuarine and palustrine wetlands that historically comprised the upper portion of Devereux Slough that was filled in the mid-1960s to create the Ocean Meadows golf course. The project also restored more than 60 acres of upland habitats that include native grassland, coastal sage scrub, riparian, oak chaparral woodland, vernal pools and patches of annual wildflowers in clay and sandy soils. This report summarizes the results from monitoring native and non-native plants, birds, small mammals, aquatic invertebrates, tree growth, and hydrological functions.

During the metamorphosis of anuran amphibians, the tail resorption process is a necessary and crucial change. One subject that has received relatively little or no attention is the expression patterns of proteins and metabolites in the different tail portions during metamorphosis, especially in highland amphibians. The mechanisms of tail resorption in three portions (the tip, middle and root) of the tail were investigated in N. pleskei G43 tadpole based on two omics (proteomic and metabolomic). Integrin αVβ3 was found to be high expressed in the distal portion of the tail, which could improve the sensitiveness to thyroid hormones in the distal portion of the tail. Muscle regression displayed a spatial pattern with stronger regression in distal and weaker one in proximal portion. Probably, this stronger regression was mainly performed by the proteases of proteasome from the active translation by ribosomes. The suicide model and murder model coexisted in the tail resorption. Meanwhile, fatty acids, amino acids, pyrimidine, and purine which derived from the breakdown of tissues can be used as building blocks or energy source for successful metamorphosis. Our data improved a better comprehension of the tail resorption mechanisms underlying the metamorphism of N. pleskei tadpole through identifying important participating proteins and metabolites. [ABSTRACT FROM AUTHOR]

At many undergraduate institutions it is not possible for every student to participate in one-on-one student-faculty research experiences. However, large numbers of undergraduates could gain research experience through the use of course-based undergraduate research (CURE) in laboratory courses. Here we present a CURE using a viral emerging infection in amphibians that is suitable for undergraduate-level students and will permit them to develop an understanding of how to calculate epidemiologically relevant sample sizes, genomic DNA extraction procedures, traditional or quantitative PCR use, and associated techniques. [ABSTRACT FROM AUTHOR]

Variation in environmental chemistry affects animal health and demographics. For instance, acidification of aquatic ecosystems (e.g., due to acid rain) can have consequences for organismal fitness. Elevated atmospheric concentrations of CO2, which reacts with water to produce carbonic acid, may affect aquatic animal physiology in multiple ways, including via reductions in pH. Such impacts have been assessed to a large extent in marine systems. Similar effects are also likely occurring in freshwater ecosystems but are relatively understudied. The goal of this project was to determine how changes in pH and CO2 concentrations influence traits and survival of animals in freshwater systems, using larval American Bullfrogs (Lithobates catesbeianus (also known as Rana catesbeiana) [Shaw, 1802]) as a model. We hypothesized that elevated CO2 concentrations and reduced pH negatively affect larval frog immune function, growth, and survival, which we tested in a laboratory aquarium experiment. Over the 27-d experiment, tadpoles were exposed to 4 treatments: 1) near-neutral pH and no gas addition (mean ± SE pH = 7.17 ± 0.05), 2) CO2 gas sparged into aquariums (pH = 5.32 ± 0.04), 3) acidified water without gas addition (pH = 6.29 ± 0.08), and 4) ambient air sparged into aquariums (control for effects of gas addition) at near-neutral pH (pH = 7.46 ± 0.03). We measured tadpole innate immune response, growth, and survival. Results from the experiment partially supported our hypothesis, with lower immune function in tadpoles exposed to acidified water or elevated CO2 compared with the control treatments and lower final mass and survival under elevated CO2. These findings motivate additional research on pH and CO2 effects on freshwater animals and suggest that increased environmental acidity and elevated CO2 can lead to negative impacts, which could contribute to reductions in wildlife health and population declines in light of ongoing environmental changes. [ABSTRACT FROM AUTHOR]

As reproduction phenologies shift with climate change, populations can experience intraspecific priority effects, wherein early hatching cohorts experience an advantage over late-hatching cohorts, resulting in altered demography. Our study objective was to identify how variation in egg hatching phenology alters intraspecific interactions in small-mouthed salamanders, Ambystoma texanum. We addressed two research questions: (Q1) How are demographic responses altered by variation in the temporal duration of hatching between cohorts, and (Q2) How does the seasonality of hatching delays affect demographic responses? We manipulated hatching phenologies of A. texanum eggs and reared larvae in outdoor mesocosms to metamorphosis. For Q1, hatching delay exhibited non-linear relationships with survival and body size, with the greatest asynchrony in cohort additions resulting in the highest mortality and largest body sizes. For Q2, hatching delay effects were stronger (i.e., survival was lower and body sizes larger) when they occurred later in the season, potentially due to temperature differences that larvae experienced. Overall, our results demonstrate that changes in intraspecific interactions due to phenological shifts can be context-dependent, depending on the strength (i.e., temporal duration) and seasonality of such processes. Identifying context-dependencies of phenological shifts will be critical for predicting changes in organismal demographics with climatic shifts. [ABSTRACT FROM AUTHOR]

Many animals exchange chemicals during courtship and mating. In some amphibians, sexual chemical communication is mediated by pheromones produced in male breeding glands that are transferred to the female's nostrils during mating. This has been mostly studied in salamanders, despite frogs having similar glands and courtship behaviours suggestive of chemical communication. In Neotropical poison frogs (Dendrobatidae and Aromobatidae), males of many species develop breeding glands in their fingers, causing certain fingers to visibly swell. Many also engage in cephalic amplexus, whereby the male's swollen fingers are placed in close contact with the female's nares during courtship. Here, we investigate the possible roles of swollen fingers in pheromone production using whole‐transcriptome sequencing (RNAseq). We examined differential gene expression in the swollen versus non‐swollen fingers and toes of two dendrobatid species, Leucostethus brachistriatus and Epipedobates anthonyi, both of which have specialised mucous glands in finger IV, the latter of which has cephalic amplexus. The overwhelming pattern of gene expression in both species was strong upregulation of sodefrin precursor‐like factors (SPFs) in swollen fingers, a well‐known pheromone system in salamanders. The differentially expressed SPF transcripts in each species were very high (>40), suggesting a high abundance of putative protein pheromones in both species. Overall, the high expression of SPFs in the swollen fingers in both species, combined with cephalic amplexus, supports the hypothesis that these traits, widespread across members of the subfamilies Colostethinae and Hyloxalinae (ca. 141 species), are involved in chemical signalling during courtship. [ABSTRACT FROM AUTHOR]

Batrachochytrium dendrobatidis (Bd) is a pathogenic chytrid fungus that is particularly lethal for amphibians. Bd can extirpate amphibian populations within a few weeks and remain in water in the absence of amphibian hosts. Most efforts to determine Bd presence and quantity in the field have focused on sampling hosts, but these data do not give us a direct reflection of the amount of Bd in the water, which are useful for parameterizing disease models, and are not effective when hosts are absent or difficult to sample. Current methods for screening Bd presence and quantity in water are time, resource, and money intensive. Here, we developed a streamlined method for detecting Bd in water with low turbidity (e.g., water samples from laboratory experiments and relatively clear pond water from a natural lentic system). We centrifuged water samples with known amounts of Bd to form a pellet and extracted the DNA from that pellet. This method was highly effective and the resulting concentrations across all tested treatments presented a highly linear relationship with the expected values. While the experimentally derived values were lower than the inoculation doses, the values were highly correlated and a conversion factor allows us to extrapolate the actual Bd concentration. This centrifuge-based method is effective, repeatable, and would greatly expand the domain of tractable questions to be explored in the field of Bd ecology. Importantly, this method increases equity in the field, because it is time- and cost-efficient and requires few resources. [ABSTRACT FROM AUTHOR]

The amount of genetic diversity within a population can affect ecological processes at population, community, and ecosystem levels. However, the magnitude, consistency, and scope of these effects are largely unknown. To investigate these issues, we conducted two experiments manipulating the amount of genetic diversity and environmental factors in larval amphibians. The first experiment manipulated wood frog genetic diversity, the presence or absence of caged predators, and competition from leopard frogs to test whether these factors affected survival, growth, and morphology of wood frogs and leopard frogs. The second experiment manipulated wood frog genetic diversity, the presence or absence of uncaged predators, and resource abundance to test whether these factors affected wood frog traits (survival, morphology, growth, development, and behavior) and other components of the ecological community (zooplankton abundance, phytoplankton, periphyton, and bacterial community structure). Genetic diversity did not affect wood frog survival, growth, and development in either experiment. However, genetic diversity did affect the mean morphology of wood frog tadpoles in the first experiment and the abundance and distribution of zooplankton in the second experiment. It did not affect phytoplankton abundance, periphyton abundance, or bacterial community structure. While effect sizes (Cohen's d) of genetic diversity were approximately half those of environment treatments, the greatest effect sizes were for interaction effects between genetic diversity and environment. Our results indicate that genetic diversity can have a large effect on ecological processes, but the direction of those effects is highly dependent upon environmental conditions, and not easily predicted from simple measures of traits. [ABSTRACT FROM AUTHOR]

The environment of an organism exerts selective pressures that affect mobility, feeding, reproduction as well as predator–prey and conspecific interactions. Land use changes induced by human activities modify these selective pressures and may result in the adaptation of organisms. Amphibians are ectotherms that typically show a biphasic life cycle with an aquatic and terrestrial phase, which makes them particularly sensitive to environmental change. We studied the impact of habitat modifications on palmate newt populations in the Ile de France region across four types of habitats: urban, mixed, agricultural, and natural with at least two replicates for each habitat type. We measured the morphology of newts using callipers, quantified maximal running and swimming speed and acceleration using high‐speed video recordings, and quantified the swelling of the hind limb linked to an inflammatory reaction. Our results show that in urban habitats, newts are larger and heavier and have a better body condition. Females, moreover, have a larger head in natural habitats, possibly due to diet specialisation of females during the breeding season. In mixed and agricultural habitats, newts have longer limbs and show a tendency to run faster, possibly associated with the selective pressures on movement in mixed habitats. Differences in inflammatory responses were observed between sexes but not habitat types. Overall, our results show differences in morphology and trends for differences in performance in newts living in different habitats suggesting that animals are adapting to human‐induced changes in their environment. [ABSTRACT FROM AUTHOR]

Wildlife–vehicle collisions (roadkill) have a direct effect on survivorship of wildlife and are a serious problem for conservation in the protected areas. Amphibians and reptiles (herpetofauna) are characterized by their seasonal activity, slow movements, and use of roads as habitat, making them especially vulnerable to roadkill. With the aim of assessing the road-related herpetofauna mortality in a protected area boundary, I performed systematic sampling from June 2015 to February 2016 along a 94-km section of Provincial Route (RP) No. 17 in Cordoba Province, Argentina. I analyzed the species composition, roadkill frequency per km, and spatial and seasonal roadkill patterns. Thirty-six herpetofauna roadkills (belonging to six species) were recorded on RP No. 17, with a roadkill frequency per km of 0.0106. Reptiles were more affected than amphibians, with Philodryas patagoniensis and Tupinambis merianae being the most commonly killed species. A stretch of 23.7 km of the sampled road was identified as a roadkill hotspot. Number of roadkills increased with monthly mean temperature, with a snake roadkill peak in spring and a lizard roadkill peak in early summer. Here, I consider which factors could be related to the identified spatial and seasonal patterns of roadkill in this region. [ABSTRACT FROM AUTHOR]

Spring viremia of carp virus (SVCV) is a rhabdovirus that primarily infects cyprinid finfishes and causes a disease notifiable to the World Organization for Animal Health. Amphibians, which are sympatric with cyprinids in freshwater ecosystems, are considered non-permissive hosts of rhabdoviruses. The potential host range expansion of SVCV in an atypical host species was evaluated by testing the susceptibility of amphibians native to the Pacific Northwest. Larval long-toed salamanders Ambystoma macrodactylum and Pacific tree frog Pseudacris regilla tadpoles were exposed to SVCV strains from genotypes Ia, Ib, Ic, or Id by either intraperitoneal injection, immersion, or cohabitation with virus-infected koi Cyprinus rubrofuscus. Cumulative mortality was 100% for salamanders injected with SVCV, 98–100% for tadpoles exposed to virus via immersion, and 0–100% for tadpoles cohabited with SVCV-infected koi. Many of the animals that died exhibited clinical signs of disease and SVCV RNA was found by in situ hybridization in tissue sections of immersion-exposed tadpoles, particularly in the cells of the gastrointestinal tract and liver. SVCV was also detected by plaque assay and RT-qPCR testing in both amphibian species regardless of the virus exposure method, and viable virus was detected up to 28 days after initial exposure. Recovery of infectious virus from naïve tadpoles cohabited with SVCV-infected koi further demonstrated that SVCV transmission can occur between classes of ectothermic vertebrates. Collectively, these results indicated that SVCV, a fish rhabdovirus, can be transmitted to and cause lethal disease in two amphibian species. Therefore, members of all five of the major vertebrate groups (mammals, birds, reptiles, fish, and amphibians) appear to be vulnerable to rhabdovirus infections. Future research studying potential spillover and spillback infections of aquatic rhabdoviruses between foreign and domestic amphibian and fish species will provide insights into the stressors driving novel interclass virus transmission events. [ABSTRACT FROM AUTHOR]

Amphibians are not only an alternative source of vital protein for humans, but also one of the best bioindicators for ecological studies. In this study, we studied the age structure, body size, and mass of an amphibian species (Pelophylax ridibundus) by sampling from two different frog farms in Türkiye. The age ranged from 4 to 13 (mean: 7.1) years in the Adana site while the age varied from 1 to 12 (mean: 5.2) years in the İstanbul site. Body size ranged between 88.21 and 103.72 mm (mean: 94.99 ± 1.15 mm) in the Adana site and 45.96 and 103.25 mm (mean: 75.90 ± 3.01 mm) in the İstanbul site. The t-test confirmed that the average age, SVL, and weight of the Adana site were higher than those of İstanbul. Body size markedly increased with age and weight (SVL-age: r = 0.659, p < 0.01; SVL-weight: r = 0.877, p < 0.001) in the İstanbul site, while in the Adana site, body size correlated only with weight. In conclusion, our research uses skeletochronology to provide demographic characteristics of marsh frogs from two unexplored frog farms located in the west and south of Türkiye. [ABSTRACT FROM AUTHOR]

The timing and size of metamorphosis are crucial for the future fitness of organisms with complex life cycles, such as amphibians. In some amphibian species, a portion of tadpoles will metamorphose in their natal year whereas others from the same cohort overwinter as tadpoles. Low temperature and food availability were previously assumed to be the underlying reasons; however, the factors influencing the decision to overwinter as tadpoles or metamorphose in the natal year have not been extensively studied. This study investigated these factors by conducting laboratory‐rearing experiments on Babina subaspera tadpoles. The tadpoles were individually reared under controlled temperature and light conditions that simulated five different growing seasons (i.e., the start month) observed in the field. Four different food quantity levels were set to induce different growth rates, which were measured individually. The results revealed that 33 tadpoles metamorphosed within their natal year, whereas 52 tadpoles were overwintered as tadpoles and metamorphosed the following spring. The size at metamorphosis was larger in tadpoles that metamorphosed after winter than in those that metamorphosed before winter. Whether tadpoles metamorphosed before or after winter was influenced by the individual growth rate and growing season. Tadpoles with slower growth rates were more likely to metamorphose after winter, possibly because slower growth prevented them from reaching the critical size threshold required for metamorphosis before winter. The threshold for the occurrence of larval overwintering varied with the growing season; tadpoles that spawned later in the year were more likely to overwinter, even with a high growth rate. The results suggested that slow‐growing B. subaspera tadpoles with insufficient time until the onset of winter would gain a higher fitness by metamorphosing after winter. This would be advantageous due to the tadpoles' potentially high survival rate during dormancy as well as their larger size at metamorphosis in the following year. [ABSTRACT FROM AUTHOR]

Reproductive strategies are one of the more fascinating aspects of Anuran biology and are likely affected by species habitat use and availability of reproductive sites. The Cerrado endemic Pithecopus oreades is a habitat specialist that reproduces in seasonal high-altitude rocky streams in Central Brazil. Herein, we describe its reproductive behavior based on observations made during two consecutive reproductive seasons in a high-altitude stream located in an open field area in Central Brazil. The reproductive activity of P. oreades occurs during the rainy season, from the very first rains, and lasts about 3 months. The species is nocturnal, showing a vocalization peak between 20:00 h and 21:00 h. Its vocalization activity was related to total precipitation. The nests, composed by only one folded leaf, are placed on shrubs along streams. The nests, which hang over the stream pools, contain approximately 30 eggs that last about 13 days of incubation, producing about 25 tadpoles per spawning. Males are territorial, remaining in the same places for more than 60 days, defending them through vocalizations and eventual physical combats. Males with a higher body condition usually stay longer in the same territory. We also recorded males displaying satellite behavior. [ABSTRACT FROM AUTHOR]

Climate and land use changes drive shifts in species distributions, causing variations in species richness. Yet the influence of shifts in species distributions on functional diversity at broad spatial scales remains uncertain. Here, we explored the potential effect of climate and land use changes on the functional diversity of European amphibian assemblages from the present to 2050, along with their effect on species richness. We performed species distribution modelling using a scenario of climate and land use change to estimate current and future potential distributions of 73 species. We estimated functional diversity using morphological and ecological functional traits. Our results highlight the intricate effects of climate and land use changes on taxonomic and functional diversity of amphibians. A climate-induced northward expansion of amphibians is anticipated, with temperature, precipitation, and forest cover prominently shaping future assemblages. Species expected to have shrinking ranges (n = 35) tend to mature sexually at a later age, produce fewer offspring per reproductive event, and live at higher maximum altitudes compared to species expected to expand (n = 38). Furthermore, trait composition changes are expected to exceed predictions based solely on species richness. These changes will vary geographically, with northern regions likely experiencing substantial increases in functional richness and functional redundancy, i.e., the coexistence of species with similar functional roles. Our findings underscore that functional diversity changes might serve as an early warning signal to assess human impacts on biodiversity. [ABSTRACT FROM AUTHOR]

A modified amphibian metamorphosis assay was performed in which Nieuwkoop and Faber (NF) stage 47 Xenopus laevis larvae were exposed to different concentrations of either perchlorate (ClO4−) or nitrate (NO3−) for 32 days. Larvae were exposed to 0.0 (control), 5, 25, 125, 625, and 3125 μg/L ClO4−, or 0 (control), 23, 71, 217, 660, and 2000 mg/L NO3−. The primary endpoints were survival, hind limb length (HLL), forelimb emergence and development, developmental stage (including time to NF stage 62 [MT62]), thyroid histopathology, wet weight, and snout‐vent length (SVL). Developmental delay as evidenced by altered stage distribution and increased MT62, a higher degree of thyroid follicular cell hypertrophy, and an increase in the prevalence of follicular cell hyperplasia was observed at concentrations ≥125 μg/L ClO4−. The no observed effect concentration (NOEC) for developmental endpoints was 25.0 μg/L ClO4− and the NOEC for growth endpoints was 3125 μg/L ClO4−. Exposure to nitrate did not adversely affect MT62, but a decreasing trend in stage distribution and median developmental stage at ≥217 mg/L NO3− was observed. No histopathologic effects associated with nitrate exposure were observed. An increasing trend in SVL‐normalized HLL was observed at 2000 mg/L NO3−. Nitrate did not alter larval growth. The NOEC for developmental endpoints was 71 mg/L NO3−, and 2000 mg/L NO3− for growth endpoints. The present study provided additional evidence that the effects and potency of nitrate and perchlorate on metamorphosis and growth in X. laevis are considerably different. A modified amphibian metamorphosis assay was performed with perchlorate (ClO4−) or nitrate (NO3−) for 32 days. The no observed effect concentration (NOEC) for developmental endpoints was 25 μg/L ClO4− and NOEC for growth endpoints was 3125 μg/L ClO4−. The NOEC for developmental endpoints was 71 mg/L, and 2000 mg/L NO3− for growth endpoints. The present study demonstrated that the effects and potency of nitrate and perchlorate on metamorphosis and growth in X. laevis are considerably different. [ABSTRACT FROM AUTHOR]

Islands harbor a significant proportion of global biodiversity and also have disproportionately high richness of introduced species relative to continents. Given the sensitivity of island ecosystems to introduced species, data deficiencies on introduction pathways, patterns of establishment, and potential impacts of introduced species can hamper mitigation and conservation efforts on islands. The Caribbean region is emerging as a hotspot for introduced amphibian and reptile (herpetofaunal) species, but patterns associated with herpetofaunal introductions on specific islands are not well explored. Here, we perform a detailed investigation of Aruba, a small Caribbean island with an exceptionally high number of introduced herpetofaunal species. We compile a database from the literature of introduction pathways, introduction years, source locations, native ranges, establishment outcomes, habitat use, and ecological impacts for three newly documented species and the 12 previously documented introduced herpetofaunal species on Aruba. From this database we synthesize emergent introduction patterns on Aruba and highlight areas of data deficiency. Overall, the patterns on Aruba echo the patterns exhibited in the greater Caribbean region. Introduction rates on Aruba have been increasing exponentially, yet the introduction pathways and source locations of most species are unknown. Following introduction, most species successfully establish localized populations in anthropogenic habitat, but the ecological impacts of most species have not been well-assessed. We suggest increased monitoring of shipments will help identify potential pathways to slow the introduction of new species, and further studies of ecological impacts of introduced species are needed. [ABSTRACT FROM AUTHOR]

Outbreaks of emerging infectious diseases are influenced by local biotic and abiotic factors, with host declines occurring when conditions favour the pathogen. Deterioration in the population of the micro-endemic Tanzanian Kihansi spray toad (Nectophrynoides asperginis) occurred after the construction of a hydropower dam, implicating habitat modification in this species decline. Population recovery followed habitat augmentation; however, a subsequent outbreak of chytridiomycosis caused by Batrachochytrium dendrobatidis (Bd) led to the spray toad's extinction in the wild. We show using spatiotemporal surveillance and mitogenome assembly of Bd from archived toad mortalities that the outbreak was caused by invasion of the BdCAPE lineage and not the panzootic lineage BdGPL. Molecular dating reveals an emergence of BdCAPE across southern Africa overlapping with the timing of the spray toad's extinction. That our post-outbreak surveillance of co-occurring amphibian species in the Udzungwa Mountains shows widespread infection by BdCAPE yet no signs of ill-health or decline suggests these other species can tolerate Bd when environments are stable. We conclude that, despite transient success in mitigating the impact caused by dams' construction, invasion by BdCAPE caused the ultimate die-off that led to the extinction of the Kihansi spray toad. [ABSTRACT FROM AUTHOR]

Environmental conditions like temperature and photoperiod can strongly shape organisms' growth and development. For many ectotherms with complex life cycles, global change will cause their offspring to experience warmer conditions and earlier-season photoperiods, two variables that can induce conflicting responses. We experimentally manipulated photoperiod and temperature during gray treefrog (Hyla versicolor) larval development to examine effects at metamorphosis and during short (10-day) and long (56-day) periods post-metamorphosis. Both early- and late-season photoperiods (April and August) decreased age and size at metamorphosis relative to the average-season (June) photoperiod, while warmer temperatures decreased age but increased size at metamorphosis. Warmer larval temperatures reduced short-term juvenile growth but had no long-term effect. Conversely, photoperiod had no short-term carryover effect, but juveniles from early- and late-season larval photoperiods had lower long-term growth rates than juveniles from the average-season photoperiod. Similar responses to early- and late-season photoperiods may be due to reduced total daylight compared with average-season photoperiods. However, juveniles from late-season photoperiods selected cooler temperatures than early-season juveniles, suggesting that not all effects of photoperiod were due to total light exposure. Our results indicate that despite both temperature and photoperiod affecting metamorphosis, the long-term effects of photoperiod may be much stronger than those of temperature. [ABSTRACT FROM AUTHOR]

This study is the first to examine the diet composition of adult Pleurodema nebulosum specimens based on an analysis of the gastrointestinal contents of 78 individuals. Analyzed herein were 40 specimens from a site disturbed due to anthropogenic action and 38 from a protected area in Argentina. Differences were found in the trophic consumption at both sites. In the protected area, P. nebulosum presented an active foraging mode, with a diet specialized in prey items from the Formicidae family. At the disturbed site, this amphibian showed a sit-and-wait foraging mode, with a generalist diet where it consumes Hemiptera and Coleoptera. In conclusion, the results support the idea that P. nebulosum adapts to local conditions of a disturbed site or protected area. In this way, it modifies its foraging mode according to habitat conditions. [ABSTRACT FROM AUTHOR]

The salamander, Ambystoma annulatum, is considered a "species of special concern" in the state of Arkansas, USA, due to its limited geographic range, specialized habitat requirements and low population size. Although metazoan parasites have been documented in this salamander species, neither its native protists nor microbiome have yet been evaluated. This is likely due to the elusive nature and under‐sampling of the animal. Here, we initiate the cataloguing of microbial associates with the identification of a new heterlobosean species, Naegleria lustrarea n. sp. (Excavata, Discoba, Heterolobosea), isolated from feces of an adult A. annulatum. [ABSTRACT FROM AUTHOR]

The hibernation of amphibians can offer a unique window into overwintering adaptation processes and host–gut microbiota interactions through changes in metabolic availability and homeostasis. We attempted to identify differences in the physiology and gut microbiome during and after hibernation in Japanese wrinkled frogs (Glandirana rugosa), an aquatic overwintering amphibian. After hibernation, the high alpha and beta diversity of the gut bacterial community appears to reflect the more diverse and complex environmental conditions. During winter, Proteobacteria dominated the majority of the gut bacterial community, likely due to high oxygen saturation. After hibernation, Firmicutes and Bacteroidetes increased, which are supportive of host metabolism by gut microbiota. Corticosterone also showed high values and variances after hibernation, presumably allowing the population to remain adaptable across a broad range of environmental gradients. Innate immunity was high after hibernation but exhibited low variation among populations, which supports the idea of a prioritized investment in immunity after hibernation. Blood biochemistry suggests that aquatic overwintering frogs have a mechanism to adapt through overhydration and regulate homeostasis through water excretion associated with the kidney and urine after hibernation. Frog populations exhibit variations and adaptability in gut microbiota and physiology during and after hibernation: Through this, they may demonstrate an adaptive response that regulates metabolic availability in preparation for unpredictable environmental changes. We also propose that the maintenance of Proteobacteria during hibernation can support the colonization of Firmicutes and Bacteroidetes after hibernation, underscoring the need to study the complex effects of gut microbiota across multiple life stages. [ABSTRACT FROM AUTHOR]

Behavioural syndromes receive attention from many disciplines for their potential evolutionary significance. Personality traits and behavioural syndromes often vary among species and even within species (i.e. between sexes and populations). Whether correlations among behaviours emerge as an adaptive response or a developmental constraint, however, is still debated. As a foundation for future studies to test the adaptive versus constraint hypotheses, we investigated repeatability and covariation of aggression and boldness between two genetically distinct populations of eastern red-backed salamanders, Plethodon cinereus , and between sexes in those populations. We predicted that individuals would show consistency in behavioural traits across trials (i.e. their behaviour would be repeatable) and that aggressive behaviour would be positively correlated with boldness. We also predicted that behavioural syndromes would vary between genetic groups and sexes. Salamanders were exposed to standard resident/intruder territorial trials to assess their aggressive behaviour. We then conducted a refuge-emergence assay to determine boldness, which involved calculating a boldness index from latency to emerge and time spent back inside refuge after initial emergence. We found that our boldness index and two aggressive displays (all-trunk-raised and look towards) were repeatable. Further analysis indicated a positive correlation between boldness and aggressiveness, suggesting the presence of a behavioural syndrome in our sample. However, we did not find strong evidence for geographical or sex differences. Our results warrant future research to determine whether a shared behavioural syndrome in our sample has resulted from adaptive or constraining mechanisms in these populations. • One of the first studies to assess behavioural repeatability in Plethodon cinereus. • One of the first studies to assess behavioural syndromes in Plethodon cinereus. • Evidence for repeatability and bold–aggressive behavioural syndrome. • Lack of geographical and sex differences in boldness and aggressiveness. • Behavioural similarities in genetically distinct groups. [ABSTRACT FROM AUTHOR]

Copyright of Magazine General Union of Arab Archaeologists is the property of General Union of Arab Archaeologists and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Genetic monitoring plays a crucial role in the conservation management of amphibians due to their vulnerability to habitat changes. Traditional biodiversity monitoring methods, such as trapping and morphological identification, are being complemented by advanced technologies that enhance species identification sensitivity and monitoring capabilities. Genetic resource availability is essential for effective amphibian biodiversity assessment and monitoring. This study aims to evaluate the current state of genetic resources and their comprehensiveness for amphibian biomonitoring and conservation in Malaysia. The study focused on seven targeted mitochondrial DNA loci, and data regarding these loci were obtained from the National Centre for Biotechnology Information (NCBI) database. The results showed that 69.8% of amphibian species in Malaysia had genetic data available for at least one or more of the targeted genes, with the 16S gene being the most widely represented. However, only 12.1% of threatened species and 61.2% of endemic species had accessible genetic information. Biological utilization was identified as the primary threat to amphibian species in Malaysia, accounting for 27.0% of recorded threats. These findings highlight the need for further improvement in achieving comprehensive genetic resource information for amphibians in Malaysia. Advancements in enpromisesntal DNA (eDNA) analysis and Next Generation Sequencing (NGS) technologies hold promise in enhancing efforts to conserve amphibian diversity. It is crucial to continue expanding genetic resources to support ongoing monitoring and preservation initiatives for amphibians in Malaysia, ensuring effective conservation management. [ABSTRACT FROM AUTHOR]

As part of the US Environmental Protection Agency's perfluoroalkyl and polyfluoroalkyl substances (PFAS) Action Plan, the agency is committed to increasing our understanding of the potential ecological effects of PFAS. The objective of these studies was to examine the developmental toxicity of PFAS using the laboratory model amphibian species Xenopus laevis. We had two primary aims: (1) to understand the developmental toxicity of a structurally diverse set of PFAS compounds in developing embryos and (2) to characterize the potential impacts of perfluorooctanesulfonic acid (PFOS), perfluorohexanesulfonic acid (PFHxS), perfluorooctanoic acid (PFOA), and hexafluoropropylene oxide‐dimer acid (HFPO‐DA a.k.a. GenX), on growth and thyroid hormone‐controlled metamorphosis. We employed a combination of static renewal and flow‐through exposure designs. Embryos were exposed to 17 structurally diverse PFAS starting at the midblastula stage through the completion of organogenesis (96 h). To investigate impacts on PFOS, PFOA, PFHxS, and HFPO‐DA on development and metamorphosis, larvae were exposed from premetamorphosis (Nieuwkoop Faber stage 51 or 54) through pro metamorphosis. Of the PFAS tested in embryos, only 1H,1H,10H,10H‐perfluorodecane‐1,10‐diol (FC10‐diol) and perfluorohexanesulfonamide (FHxSA) exposure resulted in clear concentration‐dependent developmental toxicity. For both of these PFAS, a significant increase in mortality was observed at 2.5 and 5 mg/L. For FC10‐diol, 100% of the surviving embryos were malformed at 1.25 and 2.5 mg/L, while for FHxSA, a significant increase in malformations (100%) was observed at 2.5 and 5 mg/L. Developmental stage achieved was the most sensitive endpoint with significant effects observed at 1.25 and 0.625 mg/L for FC10‐diol and FHxSA, respectively. In larval studies, we observed impacts on growth following exposure to PFHxS and PFOS at concentrations of 100 and 2.5 mg/L, respectively, while no impacts were observed in larvae when exposed to PFOA and HFPO‐DA at concentration of 100 mg/L. Further, we did not observe impacts on thyroid endpoints in exposed larvae. These experiments have broadened our understanding of the impact of PFAS on anuran development. A series of embryo and larval studies were carried out using Xenopus laevis: 1) to understand the developmental toxicity of a structurally diverse set of 17 PFAS compounds in developing embryos; and 2) to characterize the potential impacts of perfluorooctanesulfonic acid (PFOS), perfluorohexanesulfonic acid (PFHxS), perfluorooctanoic acid (PFOA) and hexafluoropropylene oxide‐dimer acid (HFPO‐DA), on growth and thyroid hormone‐controlled metamorphosis. Exposure to several of the PFAS resulted in developmental toxicity only at concentrations well above what is observed in the environment. [ABSTRACT FROM AUTHOR]

Egg dehydration can kill terrestrial frog embryos, and this threat is increasing with climate change and deforestation. In several lineages that independently evolved terrestrial eggs, and retained aquatic tadpoles, embryos accelerate hatching to escape from drying eggs, entering the water earlier and less developed. However, the cues that stimulate drying‐induced early hatching are unknown. Ammonia is a toxic, water‐soluble metabolic waste that accumulates within eggs as embryos develop and concentrates as eggs dehydrate. Thus, increasing ammonia concentration may be a direct threat to embryos in drying eggs. We hypothesized that it could serve as a cue, stimulating embryos to hatch and escape. The embryos of red‐eyed treefrogs, Agalychnis callidryas, hatch early to escape from many threats, including dehydration, and are known to use mechanosensory, hypoxia, and light cues. To test if they also use high ammonia as a cue to hatch, we exposed stage‐matched pairs of hatching‐competent, well‐hydrated sibling embryos to ammonia and control solutions in shallow water baths and recorded their behavior. Control embryos remained unhatched while ammonia‐exposed embryos showed a rapid, strong hatching response; 95% hatched, on average in under 15 min. This demonstrates that elevated ammonia can serve as a hatching cue for A. callidryas embryos. This finding is a key step in understanding the mechanisms that enable terrestrial frog embryos to escape from egg drying, opening new possibilities for integrative and comparative studies on this growing threat. Highlights: High ammonia induces hatching of the terrestrial embryos of red‐eyed treefrogs. This response may contribute to the ability of these embryos to avoid lethal dehydration by escaping from drying eggs and entering the water prematurely. [ABSTRACT FROM AUTHOR]

Mycobacterium ulcerans ecovar Liflandii (Mu Liflandii) was identified as the causative agent of mycobacteriosis in a research colony of Zaire dwarf clawed frogs (Hymenochirus boettgeri) at the University of Michigan. Clinical presentation included lethargy, generalized septicemia, cutaneous granulomas, coelomic effusion, and acute mortality. Identification of the mycobacterial species was based on molecular, microbiological, and histopathologic characteristics. These findings indicate that Mu Liflandii is a primary cause of morbidity and mortality in Zaire dwarf clawed frogs and should be considered in the differential diagnosis of sepsis and coelomic effusion in amphibians. Mycobacterial speciation is important given the variability in pathogenesis within the family Mycobacteriaceae and the implications for both animal and human health as potential zoonoses. The Zaire dwarf clawed frog is a species common in the pet trade, and these findings provide consideration for this pathogen as a potentially important public health concern. This is the first report of Mu Liflandii infection in the genus Hymenochirus and illustrates the diagnostic challenges of differentiating among both mycolactone-producing mycobacteria and Mycobacterium marinum. Furthermore, we demonstrate the utility of environmental sampling for this pathogen within the tank system, suggesting this mode of sampling could replace the need for direct frog surveillance. [ABSTRACT FROM AUTHOR]

We report a new locality for the endemic glassfrog Vitreorana franciscana Santana, Barros, Pontes & Feio, 2015 from Brazilian Cerrado, from the municipality of Nova Ponte, state of Minas Gerais, Brazil. Field visits were conducted in 2023 at Fazenda Brejão and resulted in the fourth record of this species, which expands this species’ geographic distribution by 150 km to the east. With the new record, the minimum convex polygon for the species is now 18,210 km2.

Abstract As reproduction phenologies shift with climate change, populations can experience intraspecific priority effects, wherein early hatching cohorts experience an advantage over late-hatching cohorts, resulting in altered demography. Our study objective was to identify how variation in egg hatching phenology alters intraspecific interactions in small-mouthed salamanders, Ambystoma texanum. We addressed two research questions: (Q1) How are demographic responses altered by variation in the temporal duration of hatching between cohorts, and (Q2) How does the seasonality of hatching delays affect demographic responses? We manipulated hatching phenologies of A. texanum eggs and reared larvae in outdoor mesocosms to metamorphosis. For Q1, hatching delay exhibited non-linear relationships with survival and body size, with the greatest asynchrony in cohort additions resulting in the highest mortality and largest body sizes. For Q2, hatching delay effects were stronger (i.e., survival was lower and body sizes larger) when they occurred later in the season, potentially due to temperature differences that larvae experienced. Overall, our results demonstrate that changes in intraspecific interactions due to phenological shifts can be context-dependent, depending on the strength (i.e., temporal duration) and seasonality of such processes. Identifying context-dependencies of phenological shifts will be critical for predicting changes in organismal demographics with climatic shifts.

We confirm the presence of the genus Plectrohyla Brocchi, 1877 in Nicaragua and report the first records of Plectrohyla guatemalensis Brocchi, 1877 in the country based on three specimens collected in 1983 from the central mountain range of Matagalpa department. These specimens collected over 40 years ago are the southernmost records for the species and expand its geographic distribution by approximately 175 km southeast from its nearest recorded locality in Honduras.

Based on molecular and morphological evidence, we report the first record of Eleutherodactylus nitidus (Peters, 1870) from Mexico City, in the urban area of Panteón Xilotepec, Xochimilco. We discuss the remarkable urban adaptability of Eleutherodactylus and the need for additional sampling to determine if E. nitidus is native or introduced to Mexico City.

Abstract Gut microbiota impact host physiology, though simultaneous investigations in ectothermic vertebrates are rare. Particularly, amphibians may exhibit more complex interactions between host physiology and the effects of gut microbiota due to the combination of seasonal changes and complex life histories. In this study, we assessed the relationships among food resources, gut bacterial communities, and host physiology in frogs (Phelophylax nigromaculatus), taking into account seasonal and life history variations. We found that food sources were not correlated with physiological parameters but had some relationships with the gut bacterial community. Variations in gut bacterial community and host physiology were influenced by the combined effects of seasonal differences and life history, though mostly driven by seasonal differences. An increase in Firmicutes was associated with higher fat content, reflecting potential fat storage in frogs during the non-breeding season. The increase in Bacteroidetes resulted in lower fat content in adult frogs and decreased immunity in juvenile frogs during the breeding season, demonstrating a direct link. Our results suggest that the gut microbiome may act as a link between food conditions and physiological status, and that the combined effect of seasons and life history could reinforce the relationship between gut microbiota and physiological status in ectothermic animals. While food sources may influence the gut microbiota of ectotherms, we contend that temperature-correlated seasonal variation, which predominately influences most ectotherms, is a significant factor.

Declines in biodiversity and ecosystem health due to climate change are raising urgent concerns. In response, large-scale multispecies monitoring programmes are being implemented that increasingly adopt sensor-based approaches such as acoustic recording. These approaches rely heavily on ecological data science. However, developing reliable algorithms for processing sensor-based data relies heavily on labelled datasets of sufficient quality and quantity. We present a dataset of 1,575 dawn chorus soundscape recordings, 141 being fully annotated (n = 32,994 annotations) with avian, mammalian and amphibian vocalisations. The remaining recordings were included to facilitate novel research applications. These recordings are paired with 48 site-level climatic, forest structure and topographic covariates. This dataset provides a valuable resource to researchers developing acoustic classification algorithms or studying biodiversity and wildlife behaviour and its relationship to environmental gradients. The dawn chorus recordings were collected as part of a long-term Northern Spotted Owl monitoring program; this demonstrates the complementary value of harnessing existing monitoring efforts to strengthen biodiversity sampling.This dataset of dawn chorus soundscape recordings is one of the few open-access acoustic datasets annotated with non-biotic and both interspecific (across species) and intraspecific (within species) bird, mammal and amphibian sonotypes and the first that is paired with climatic, forest structure and topographical covariates extracted at recorder locations. This makes it a valuable resource for researchers studying the dawn chorus and its relationship to the environment.

Different sources of information indicate the possible presence of Teratohyla midas (Lynch & Duellman, 1973) in Bolivia; however, none of them confirm this scenario. Here we confirm the presence of T. midas in the northern Bolivian Amazon (Pando Department) and extend the geographical distribution of the species to include Bolivia. Likewise, we contribute information on some aspects of this species’ behavior and natural history.

Abstract The African clawed frog, Xenopus laevis, has been used as a laboratory animal for decades in many research areas. However, there is a lack of knowledge about the nutritional physiology of this amphibian species and the feeding regimen is not standardized. The aim of the present study was to get more insights into the nutrient metabolism and feeding behavior of the frogs. In Trial 1, adult female X. laevis were fed either a Xenopus diet or a fish feed. After 4 weeks, they were euthanized, weighed, measured for morphometrics and dissected for organ weights and whole-body nutrient analysis. There were no significant differences between the diet groups regarding the allometric data and nutrient contents. The ovary was the major determinant of body weight. Body fat content increased with body weight as indicator of energy reserves. In Trial 2, 40 adult female frogs were monitored with a specifically developed digital tracking system to generate heat-maps of their activity before and up to 25 min after a meal. Three diets (floating, sinking, floating & sinking) were used. The main feed intake activity was fanning the feed into the mouth, peaking until 20 min after the meal. The different swimming characteristics of the diets thereby influenced the activity of the animals. Our dataset helps to adjust the feeding needs to the physical composition and also to meet the natural behavioral patterns of feed intake as a prerequisite of animal wellbeing and animal welfare in a laboratory setting.

Abstract Background Anuran metamorphosis, which is driven by thyroid hormone (TH)-mediated processes, orchestrates intricate morphological and functional transformations for the transition from aquatic tadpoles to terrestrial life, providing a valuable model for studying organ functionalization, remodeling, and regression. Larva-specific organ regression is one of the most striking phenomena observed during the anuran metamorphic climax. While previous studies extensively analyzed the regression mechanisms of the tail, the molecular processes governing gill resorption remain elusive. Results We employed Microhyla fissipes as a model, and utilized a comprehensive approach involving histological analysis, transmission electron microscopy, and transcriptomics to unravel gill development and resorption. The pro-metamorphic stages revealed highly developed gill structures, emphasizing their crucial role as the primary respiratory organ for tadpoles. The transcriptomic analysis highlighted the upregulation of genes associated with enhanced respiratory efficiency, such as hemoglobin and mucins. However, as metamorphosis progressed, gill filaments underwent shrinkage, decreases in blood vessel density, and structural changes that signified a decline in respiratory function. The molecular mechanisms driving gill resorption involved the TH pathway—in particular, the upregulation of thyroid hormone receptor (TR) β, genes associated with the tumor necrosis factor pathway and matrix metalloproteinases. Two distinct pathways orchestrate gill resorption, involving apoptosis directly induced by TH and cell death through the degradation of the extracellular matrix. In addition, metabolic reorganization during metamorphosis is a complex process, with tadpoles adapting their feeding behavior and mobilizing energy storage organs. The gills, which were previously overlooked, have been unveiled as potential energy storage organs that undergo metabolic reorganization. The transcriptomic analysis revealed dynamic changes in metabolism-related genes, indicating decreased protein synthesis and energy production and enhanced substrate transport and metabolism during metamorphic climax. Conclusion This study sheds light on the structural, molecular, and metabolic dynamics during gill development and resorption in M. fissipes. The findings deepen our understanding of the intricate mechanisms governing organ regression and underscore the pivotal role of the gills in facilitating the transition from aquatic to terrestrial habitats.

A climbing mantella frog (Mantella laevigata) was presented with nodular thickened skin. Histological examination revealed dermal nodules composed of differentiated bone consistent with miliary osteoma cutis, a non‐neoplastic condition where bone is abnormally deposited within the skin. This is the first report of idiopathic osteoma cutis in an amphibian. [ABSTRACT FROM AUTHOR]

Conservation and management of drylands is a global challenge. Key attributes of these ecosystems, such as dominant vegetation including shrubs, can provide a crucial mechanism to inform conservation strategies. The shrub species Ephedra californica and Larrea tridentata are common native shrub species within the deserts of California and frequently benefit other plant and animal species. Here, we tested the hypothesis that shrubs support reptile and amphibian communities through relative increases in available habitat, estimated through increasing shrub densities at the site level. Reported occurrence data from the Global Biodiversity Information Facility (GBIF) and high-resolution satellite images were used to test for local-to-regional patterns in reptile and amphibian distribution and diversity by shrub densities at sites. At 43 distinct sites, the relationship between shrub density and reported reptile and amphibian communities was also tested. A total of 71 reptile and amphibian species were reported regionally. Increases in shrub density across sites positively influenced the relative abundance and richness of reptiles and amphibians observed. Moreover, increasing shrub density also had a positive influence on species evenness. Aridity differences between sites did not significantly influence the relationship between shrub density and reptiles and amphibians suggesting that the relationship was robust. This study highlights the importance of foundational shrub species in supporting reptile and amphibian communities in arid and semi-arid regions. Large-scale patterns of biodiversity in deserts can be supported by positive plant-animal interactions including small islands of fertility and resources for animals in the context of a warming climate. [ABSTRACT FROM AUTHOR]

In May 2023, herpetologists from six countries converged at the 8th Conference on the Biology of Plethodontid Salamanders in Hammond, Louisiana to share their latest cutting-edge research. The conference was hosted by the Department of Biological Sciences at Southeastern Louisiana University. Dr. Richard Bruce was the honoree. The presentations covered a diverse array of topics from gene expression to behavior to speciation, illustrating the value of plethodontid salamander biology to a range of disciplines. This special issue of Herpetologica includes 16 papers highlighting a range of research on plethodontids and encouraging new approaches to tackle old and new questions. [ABSTRACT FROM AUTHOR]

In recent years, the potential to locate endangered animals using scent trained detection dogs (conservation detection dogs) has gained attention. Among vertebrates, conservation detection dogs have demonstrated a remarkable capacity to detect the scent of endangered mammals, reptiles, and birds, but their use in detecting amphibians is only beginning to be explored. A lack of work in this area is surprising given that amphibians are declining faster than any other vertebrate taxa. Moreover, amphibians are generally small, highly cryptic and breed in complex habitats, making them difficult to locate for the purpose of monitoring or establishing conservation breeding programs. This study aimed to provide a preliminary investigation into whether conservation detection dogs can be imprinted on the scent of the critically endangered Baw Baw frog (Philoria frosti) under captive conditions, and then effectively trained to locate wild frogs in their complex natural habitat. Two conservation detection dogs were trained to identify and locate P. frosti scent under controlled conditions before assessing their ability to locate wild P. frosti. Both conservation detection dogs were effective at locating P. frosti scent under controlled conditions, and also demonstrated an ability to detect live frogs under natural conditions. From an applied perspective, our findings provide new evidence that conservation detection dogs are capable of learning to detect the scent of small, cryptic anuran species. They also indicate that detection dogs are capable of locating frogs in highly complex forest habitat, confirming their untapped potential to aid in the management of imperiled species that have previously proven difficult to detect, monitor, and protect. We discuss the limitations of our approach and provide recommendations to help direct future amphibian conservation detection dog research. [ABSTRACT FROM AUTHOR]

Host-associated microbial communities, like other ecological communities, may be impacted by the colonization order of taxa through priority effects. Developing embryos and their associated microbiomes are subject to stochasticity during colonization by bacteria. For amphibian embryos, often developing externally in bacteriarich environments, this stochasticity may be particularly impactful. For example, the amphibian microbiome can mitigate lethal outcomes from disease for their hosts; however, this may depend on microbiome composition. Here, we examined the assembly of the bacterial community in spring peeper (Pseudacris crucifer) embryos and tadpoles. First, we reared embryos from identified mating pairs in either lab or field environments to examine the relative impact of environment and parentage on embryo and tadpole bacterial communities. Second, we experimentally inoculated embryos to determine if priority effects (i) could be used to increase the relative abundance of Janthinobacterium lividum, an amphibian-associated bacteria capable of preventing fungal infection, and (ii) would lead to observed differences in the relative abundances of two closely related bacteria from the genus Pseudomonas. Using 16S rRNA gene amplicon sequencing, we observed differences in community composition based on rearing location and parentage in embryos and tadpoles. In the inoculation experiment, we found that priority inoculation could increase the relative abundance of J. lividum, but did not find that either Pseudomonas isolate was able to prevent colonization by the other when given priority. These results highlight the importance of environmental source pools and parentage in determining microbiome composition, while also providing novel methods for the administration of a known amphibian probiotic. [ABSTRACT FROM AUTHOR]

Advertisement calls are the main communication form of anurans, and other individuals can use it to evaluate several aspects of the calling individual. In this context, environmental disturbances, such as traffic noise, can potentially affect this recognition. Therefore, this study aims to evaluate the response of Aplastodiscus leucopygius to traffic noise in a fragment of Atlantic Forest within the city of São Paulo. The experimentation consisted of recording the calling individual previously, during and after an exposure to urban noise. After that, individuals were measured to evaluate the Scaled Mass Index (SMI), and individual and environmental temperatures were taken. Also, considering that individuals of this species present harmonic shifting, we tried to evaluate which factors (individual, acoustic, or environmental) are associated with this phenomenon. We observed that the individuals showed an increase in call activity after exposure to traffic noise, but none of the evaluated aspects here could explain the harmonic shifting in their calls. Considering that this increasing on call activity also means an increasing of individual's expense of energy, traffic noise is potentially harmful to the communication of A. leucopygius and, consequently, to its permanence in the site. [ABSTRACT FROM AUTHOR]

Conservation breeding programs have long been an important management tool for species recovery. Recently, breeding programs have begun to integrate next generation sequencing data into pedigree-based management strategies designed to maximize retention of genetic diversity and minimize inbreeding. In 2005, an ex situ breeding program for two of the three extant, geographically separate populations of the endangered southern mountain yellow-legged frog (Rana muscosa) was established at the San Diego Zoo Wildlife Alliance. To provide improved breeding recommendations for the species, we conducted molecular population genetic assessments using double digest restriction site-associated DNA sequencing data. We first studied genetic diversity, population differentiation, and genetic structure of wild frogs to validate the status of management units in R. muscosa. Genetic diversity was relatively low (HO = 0.166–0.245), population differentiation moderate (FST = 0.29), and patterns of genetic structure and admixture supported the evolutionary divergence of frogs by mountain ranges with limited gene flow. In the breeding program, relatedness estimates identified close relatives amongst the founders, and molecularly-derived kinship values were used to determine and rank suitable breeders to minimize population mean kinship. Ex situ management recommendations highlight the need for importing additional founders from the wild to enhance genetic diversity in the breeding program, as an effective source for genetic restoration. Alternatively, the use of advanced reproductive technologies to capture wild diversity without removal of individuals from the wild seem promising. [ABSTRACT FROM AUTHOR]

Amphibians undergo a metamorphic developmental process primarily regulated by thyroid hormone (TH), exhibiting dramatic changes in external morphology and internal tissues and organs and even in the expression of TH target genes, providing an ideal model for studying and testing thyroid disruptors. Since 2009, the Organization for Economic Cooperation and Development (OECD) has successively released three testing guidelines for thyroid disruptors based on amphibians, namely the amphibian metamorphosis assay (AMA, TG 231), the larval amphibian growth and development assay (LAGDA, TG 241), and the Xenopus eleutheroembryo thyroid assay (XETA, TG 248). These three assays are currently incorporated into The OECD Conceptual Framework for Testing and Assessment of Endocrine Disrupting Chemicals for screening and testing thyroid disruptors. Compared to AMA and LAGDA, which are based on spontaneous metamorphosis, Chinese researchers have developed the T3-induced Xenopus metamorphosis assay (TiXMA) for screening thyroid disruptors. To promote the understanding and application of these assays, this paper reviews the principles, endpoints, result interpretation, and the current application status of each assay, preliminarily compares their sensitivity and specificity for thyroid disruptors. It emphasized the need to validate these assays through testing more chemicals. [ABSTRACT FROM AUTHOR]

Simple Summary: Intergenerational justice entitles future generations to the maximum retention of Earth's biodiversity. The 2022 United Nations COP 15, "Ecological Civilisation: Building a Shared Future for All Life on Earth", aims to safeguard 30% of Earth's terrestrial environment by 2030, and COP 28 addressed the climate catastrophe. Reproduction biotechnologies, biobanks, and conservation breeding programs (RBCs) are also needed to perpetuate amphibian diversity and prevent extinctions. We focused this review on three core themes: the need and potential of RBCs to satisfy sustainability goals, the technical state and current application of RBCs, and how to achieve the future potentials of RBCs in a rapidly evolving environmental and cultural landscape. The full potential of amphibian RBCs requires a democratic, globally inclusive organisation that focuses on developing facilities in the regions with the highest amphibian diversity. Intergenerational justice entitles the maximum retention of Earth's biodiversity. The 2022 United Nations COP 15, "Ecological Civilisation: Building a Shared Future for All Life on Earth", is committed to protecting 30% of Earth's terrestrial environments and, through COP 28, to mitigate the effects of the climate catastrophe on the biosphere. We focused this review on three core themes: the need and potential of reproduction biotechnologies, biobanks, and conservation breeding programs (RBCs) to satisfy sustainability goals; the technical state and current application of RBCs; and how to achieve the future potentials of RBCs in a rapidly evolving environmental and cultural landscape. RBCs include the hormonal stimulation of reproduction, the collection and storage of sperm and oocytes, and artificial fertilisation. Emerging technologies promise the perpetuation of species solely from biobanked biomaterials stored for perpetuity. Despite significant global declines and extinctions of amphibians, and predictions of a disastrous future for most biodiversity, practical support for amphibian RBCs remains limited mainly to a few limited projects in wealthy Western countries. We discuss the potential of amphibian RBCs to perpetuate amphibian diversity and prevent extinctions within multipolar geopolitical, cultural, and economic frameworks. We argue that a democratic, globally inclusive organisation is needed to focus RBCs on regions with the highest amphibian diversity. Prioritisation should include regional and international collaborations, community engagement, and support for RBC facilities ranging from zoos and other institutions to those of private carers. We tabulate a standard terminology for field programs associated with RBCs for publication and media consistency. [ABSTRACT FROM AUTHOR]

The success of ponds constructed to restore ecological infrastructure for pond‐breeding amphibians and benefit aquatic biodiversity depends on where and how they are built. We studied effects of pond and landscape characteristics, including connectivity, on metapopulation dynamics of 12 amphibian species in Switzerland. To understand the determinants of long‐term occupancy (here summarized as incidence), environmental effects on both colonization and persistence should be considered. We fitted dynamic occupancy models to 20 years of monitoring data on a pond construction program to quantify effects of pond and landscape characteristics and different connectivity metrics on colonization and persistence probabilities in constructed ponds. Connectivity to existing populations explained dynamics better than structural connectivity metrics, and simple metrics (distance to the nearest neighbor population, population density) were useful surrogates for dispersal kernel‐weighted metrics commonly used in metapopulation theory. Population connectivity mediated the persistence of conservation target species in new ponds, suggesting source–sink dynamics in newly established populations. Population density captured this effect well and could be used by practitioners for site selection. Ponds created where there were 2–4 occupied ponds within a radius of ∼0.5 km had >3.5 times higher incidence of target species (median) than isolated ponds. Species had individual preferences regarding pond characteristics, but breeding sites with larger (≥100 m2) total water surface area, that temporarily dried, and that were in surroundings with maximally 50% forest benefitted multiple target species. Pond diversity will foster amphibian diversity at the landscape scale. [ABSTRACT FROM AUTHOR]

Parasites represent a ubiquitous threat for most organisms, requiring potential hosts to invest in a range of strategies to defend against infection—these include both behavioural and physiological mechanisms. Avoidance is an essential first line of defence, but this behaviour may show a trade-off with host investment in physiological immunity. Importantly, while environmental stressors can lead to elevated hormones in vertebrates, such as glucocorticoids, that can reduce physiological immunity in certain contexts, behavioural defences may also be compromised. Here, we investigate anti-parasite behaviour and immune responses against a trematode (flatworm) parasite by larval amphibians (tadpoles) exposed or not to a simulated general stressor in the form of exogenous corticosterone. Tadpoles that were highly active in the presence of the trematode infectious stage (cercariae) had lower infection loads, and parasite loads from tadpoles treated only with dechlorinated water were significantly lower than those exposed to corticosterone or the solvent control. However, treatment did not affect immunity as measured through white blood-cell profiles, and there was no relationship between the latter and anti-parasite behaviour. Our results suggest that a broad range of stressors could increase host susceptibility to infection through altered anti-parasite behaviours if they elevate endogenous glucocorticoids, irrespective of physiological immunity effects. How hosts defend themselves against parasitism in the context of multiple challenges represents an important topic for future research, particularly as the risk posed by infectious diseases is predicted to increase in response to ongoing environmental change. [ABSTRACT FROM AUTHOR]