Search Results (107)

Emerging infectious diseases are major threats to amphibian biodiversity. Ranaviruses (Family Iridoviridae) are a group of globally emerging infections that infect poikilothermic vertebrates. In the United Kingdom, the emergence of this group of viruses has been followed by the decline in populations of common frogs (Rana temporaria) across the country, especially in the southeast of England. Simple susceptible-infected (SI) and combinatorial models have been developed to explain the spread of ranavirus in populations of common frogs; here, we use those models as a basis for developing a simple transmission model using cellular automata with the programming language Python. Full article

Urban-driven landscape fragmentation is a major factor contributing to amphibian population decline yet its genetic consequences remain incompletely understood. We examined the genetic structure and variability of the common toad (Bufo bufo) in Warsaw, Poland, using seven nuclear microsatellite loci and mitochondrial cytochrome b sequences (800 bp). Samples (N = 97) were collected from six breeding sites representing contrasting urban habitats on both banks of the Vistula River. Genetic analyses revealed low but significant population differentiation, elevated inbreeding coefficients, and a heterozygosity deficit despite relatively high effective population sizes. This pattern is consistent with post-fragmentation genetic inertia, in which demographic buffering temporarily maintains genetic diversity despite reduced connectivity. Consequently, contemporary genetic patterns may underestimate the extent of ecological isolation imposed by urban infrastructure. Mitochondrial analyses identified seven haplotypes, including six previously unreported, forming a star-like network topology indicative of a single postglacial colonization event. The Vistula River did not constitute a significant barrier to gene flow, based on pairwise F_ST and hierarchical AMOVA. Supervised feature selection (MCFS-ID) identified specific alleles and body mass as key discriminants among sites, suggesting emerging responses to local urban conditions. Our results indicate that urban common toad populations can retain substantial genetic variation despite fragmentation, although continued isolation may ultimately increase inbreeding and genetic drift. Full article

Microplastic (MP) contamination has become a defining feature of twenty-first century environmental change, yet the toxicological and ecological consequences for amphibians and reptiles—two vertebrate classes already facing severe extinction pressures—remain fragmented across taxa, regions, and methodological traditions. Here, we synthesize field and experimental evidence from five continents to provide a taxonomically balanced, mechanistically grounded, and geographically explicit assessment of MP exposure, bioaccumulation, and toxicity in herpetofauna, drawing on a structured literature search in Web of Science, Scopus, and PubMed (January 2015—March 2026). Field detection rates of MPs in amphibian larvae range from 26% in conservatively screened Central European populations to 73–80% in anuran tadpoles from high-anthropogenic-pressure Anatolian catchments, with fibrous polyethylene terephthalate (PET), polyethylene (PE), and polypropylene (PP) particles dominating the detected burden. Mechanistic evidence converges on oxidative stress cascades, hypothalamic–pituitary–thyroid axis disruption, gut and cutaneous microbiome dysbiosis, and compromised antiviral and antifungal immunity, with the latter potentially amplifying vulnerability to Batrachochytrium dendrobatidis and to ranavirus. Among reptiles, sea turtles display near-universal MP ingestion with documented maternal transfer to eggs; freshwater turtles, terrestrial squamates, and crocodilians remain critically understudied. Three structural asymmetries constrain current ecotoxicological risk characterization: taxonomic bias toward anurans and sea turtles, geographic bias toward the Global North, and experimental bias toward acute, supra-environmental laboratory exposures using pristine, single-polymer particles that fail to capture the chemical complexity of weathered field mixtures. We argue that MP burden may warrant consideration as a candidate stressor criterion within IUCN Red List assessments and within environmental risk assessment frameworks for freshwater and terrestrial biodiversity once a robust quantitative relationship between MP burden and demographic decline or population-level fitness has been established, and propose six hypothesis-driven research priorities: methodological standardization, reptile toxicokinetics, transgenerational epigenetics, MP–pathogen microbiome interactions and their translation into population viability models, temperature × MP interaction under climate warming, and population-genetic consequences of contemporary MP-driven selection, as the most tractable avenues for ecotoxicological progress and for the development of herpetofauna-specific risk characterization frameworks. Full article

Climate change threatens global biodiversity, with amphibians from climatically stable and geographically restricted ecosystems such as Mexico’s montane cloud forest (CF) being particularly vulnerable. This study evaluated the potential impacts of climate scenarios on the distribution and richness of 53 endemic anuran species. We used ecological niche models (MaxEnt) to project current and future distributions (year 2100) under the SSP2-4.5 and SSP5-8.5 scenarios, and assessed species representativeness within federal Protected Natural Areas (PNAs). The results indicate that 71.7% of species already fall into an IUCN threat category. Widespread habitat contraction is observed under the climate projections, with average losses of 40.3% (SSP2-4.5) and 45.5% (SSP5-8.5). Twelve species (22.6%) could lose over 90% of their current distribution, suggesting a high risk of functional extinction. Only 15.3% of occurrence records currently fall within PNAs, and key reserves such as Los Tuxtlas and La Sepultura are projected to experience significant richness declines. These patterns are consistent with an “escalator to extinction” process driven by altitudinal compression of climatic niches. Adaptive conservation strategies are urgently needed, including the identification of climate microrefugia and the establishment of connectivity corridors to enhance the long-term persistence of endemic anurans under climate change. Full article

The Southern Stuttering Frog, Mixophyes australis, is a newly described threatened species endemic to Australia that is suffering severe and ongoing declines. The species is currently presumed extinct from the southern two thirds of its range, primarily driven by the amphibian chytrid fungus (Batrachochytrium dendrobatidis; Bd). In response to the species’ decline, a conservation breeding program (CBP) was established at Symbio Wildlife Park to secure an insurance population and support future reintroductions. Herein, the establishment and management of the CBP for M. australis is described. We detail the captive husbandry framework and tracing progress from the collection of 200 wild-caught tadpoles in April 2022, through to the successful reproduction of the founder colony. Following the revision of husbandry and water management practices, and disease treatment in quarantine to overcome initial mortality, 89 Bd-free individuals were transferred to the breeding facility to establish the insurance colony. Critically, the program has achieved consistent and successful reproduction commencing in April 2024, within 2 years of tadpole collection. The breeding cohort exhibited a distinctive bimodal annual reproductive pattern in captivity, with clear peaks in breeding activity in Austral autumn (March–May) and mid-winter to early spring (July–September). We detail effective husbandry protocols for all life stages of the species, which has resulted in the generation of clutches exhibiting high fertility and high tadpole survivorship. Overall, the program to date has contributed to the reintroduction of over 7700 first-generation (F1) tadpoles and 59 head-started founder (F0) adults across 15 release sites within the species’ historical range in NSW. Herein, we provide important natural history data for the species and considerations for their breeding in captivity, which can inform future conservation efforts for this and other threatened frog species globally. Full article

Itraconazole is an antifungal drug used to treat chytridiomycosis, one of the leading causes of global amphibian decline in species such as the critically endangered Panamanian golden frog (Atelopus zeteki). Despite its widespread use for prophylaxis and treatment in both assurance colonies and free-ranging amphibians, there is minimal pharmacologic information to guide dosing. In experiment A, frogs were exposed to 0.01% itraconazole for 10 min and tissue samples were analyzed at various time points from 1 to 84 h. In experiment B, frogs were divided into six groups and exposed to itraconazole in different combinations of concentration (0.01% or 0.001%) and time (5, 10, or 15 min) over 10 days of treatment. Tissue concentrations were quantified via high-performance liquid chromatography. In experiment A, following a one-time dose, itraconazole concentrations remained high until the end of the experiment at 84 h. In experiment B, at 0.01% itraconazole daily for 10 days, skin and liver concentrations were high and increased substantially over the 10-day treatment course. Frogs exposed at the lower concentration (0.001%) had tissue concentrations that appeared to remain steady. At the reported doses over 10 days, there was no histologic evidence of hepatic toxicity, although one frog was found dead in the low-dose bath at 84 h and could not be further analyzed. This experiment is an excellent example of assurance colonies providing evidence-based information for the improved care and welfare of amphibians in order to prepare for future free-ranging populations. Full article

Highway construction is a major driver of landscape transformation, yet its integrated effects on ecological functions in forested regions under strong ecological governance remain poorly quantified. This study examines spatiotemporal changes in land use, landscape patterns, ecosystem service value (ESV), and habitat connectivity within 1–5 km buffer zones along three highways in Zhejiang, China, from 2000 to 2023. Results indicate that highway-induced fragmentation was land-use-specific: cropland and construction land became more fragmented, while forests maintained high spatial cohesion due to protective policies. ESV per hectare increased over time and with distance from highways, driven by forest expansion and economic revaluation. In contrast, habitat connectivity for reptiles, amphibians, mammals, and birds declined, revealing a decoupling between ESV enhancement and connectivity conservation. These findings underscore the context-dependent impacts of highways and highlight the need for integrated management strategies that preserve forest integrity to balance ecological functions in rapidly developing regions. Full article

Amphibian populations are undergoing dramatic global declines, with infectious diseases recognized as major contributors. While chytridiomycosis, caused by Batrachochytrium dendrobatidis (Bd), and disease caused by ranaviruses are well known, herpesviruses in amphibians remain comparatively neglected. We conducted a passive survey using carcasses collected between 2022 and 2025 in Schleswig-Holstein, northern Germany. Dead amphibians (n = 187) were dissected. Skin, kidney, liver, and brain samples were screened for Bd, ranaviruses, bufonid herpesvirus 1 (BfHV1), and ranid herpesvirus 3 (RaHV3) by PCR. BfHV1 was detected in nearly half of the Bufo bufo (common toads; 48.6%), while RaHV3 was identified in 23.6% of the Rana temporaria (common frogs) examined. Bd was detected in a single B. bufo, while ranaviruses were not detected. BfHV1 was present in skin, liver, kidney, and brain samples, whereas RaHV3 was detected exclusively in skin samples. No macroscopical or histological lesions characteristic of herpesviruses or Bd were found. However, the carcass-based approach frequently limited detailed examination due to compromised sample quality. Our findings confirm the presence of amphibian herpesviruses (BfHV1 and RaHV3) in the region without associated lesions, raising questions about their potential to cause systemic infections. Furthermore, our results highlight the limitations of carcass-based surveillance and underscore the need for complementary diagnostic approaches, such as immunohistochemistry and meta-omics. Full article

In August 2023, a large forest fire burned more than 60% of the Dadia–Lefkimi–Soufli Forest National Park in northeastern Greece, following another large fire in 2022. To quantify the effects of these fires on local herpetofauna, we analyzed community composition, abundance, and diversity before and after the 2023 event. Standardized visual encounter surveys were conducted across 29 sites between 2015 and 2024, spanning burned and unburned areas. Species richness, abundance, and diversity metrics, together with Bray–Curtis community dissimilarities, were compared across sampling periods and fire-severity classes. Amphibian assemblages showed high postfire persistence, with 82% of regional species still detected and no significant changes in diversity indices, likely reflecting the buffering role of perennial streams and other hydrologically stable refugia. In contrast, reptile communities showed clear compositional shifts and experienced severe declines: overall reptile species richness decreased to 30% of prefire levels and diversity indices dropped significantly. Tortoises (i.e., Testudo graeca, T. hermanni) declined by nearly 90% relative to prefire estimates, indicating high vulnerability of low-mobility, long-lived species. Snakes were not detected in any burned sites, whereas only a few small-bodied lizards and the freshwater turtle Mauremys rivulata persisted locally. These findings demonstrate that extreme, landscape-scale fires can restructure reptile communities in Mediterranean forests, particularly where long-term habitat change and drought had already reduced population resilience. The study underscores the need for targeted postfire restoration, conservation planning for slow-dispersing taxa, and long-term biodiversity monitoring under increasingly frequent fire regimes. Full article

Background/Objectives: In humans, diseases such as oral cancer may require surgical amputation of the jaw. This severe disruption causes impairments in eating, swallowing, and speech, leading to a significant decline in quality of life. In contrast, newts, a group of urodele amphibians, can regenerate their jaws even in adulthood. This study explored how adult newts reconstruct lower jaws after substantial loss and clarified how this process contributes to rapid functional recovery when feeding becomes impossible. Methods: Adult Japanese fire-bellied newts (Cynops pyrrhogaster) underwent surgical amputation of the anterior half of their lower jaws. Regeneration was monitored for 64 weeks using histological analyses of bone, cartilage, and dental tissues and micro-computed tomography (micro-CT)-based osteomorphometry to quantify structural changes in the regenerating lower jaw. Results: Histological observations and osteomorphometry revealed the following: epithelial coverage of the amputation margin; ectopic cartilage formation, growth, and regression; bone resorption at the amputation margin prior to bone regeneration; anterior extension of the lower jaw bone along the original dentition position, followed by its thickening; and dental lamina invagination with tooth germ formation. Through these processes, the lower jaw bone, Meckel’s cartilage, and dentition were restored by 64 weeks post-amputation to their pre-amputation states. Conclusions: This study delineates the full sequence of lower jaw regeneration in adult newts, demonstrating complete restoration of bone, cartilage, and teeth after substantial lower jaw loss. These findings provide a detailed framework for understanding urodele jaw regeneration and may inform future strategies for promoting jaw reconstruction in humans. Full article

Climate change poses a serious threat to amphibians and reptiles, which are especially vulnerable because of limited thermoregulatory capacity and restricted dispersal. We used an ensemble species distribution modeling framework to assess habitat determinants, niche breadth, and climate-driven distribution changes for eight legally protected endangered amphibian and reptile species in South Korea. Occurrence records collected between 1997 and 2021 were combined with ten bioclimatic, topographic, and hydrological predictors, and 11 species distribution modeling algorithms (SDMs), including Random Forest and MaxEnt, were implemented and combined into weighted ensemble predictions. The weighted ensemble model showed high predictive performance (mean ROC–AUC = 0.897; overall mean across all SDMs = 0.843). Variable-importance analysis revealed clear taxonomic contrasts: reptiles exhibited approximately 1.7-fold greater dependence on temperature variables than amphibians, whereas amphibians were more strongly associated with precipitation and topographic context. Environmental niche-breadth analysis identified Sibynophis chinensis, Hynobius yangi, and Dryophytes suweonensis as narrow- or moderate-niche specialists largely constrained by precipitation of the driest month and a small set of climatic variables. Under moderate (SSP2-4.5) and high (SSP5-8.5) emission scenarios, areas of high species richness are projected to decline by 22% and 45%, respectively, by the 2070s, with distribution centroids shifting northeastward and pronounced habitat loss in western lowland plains. Priority conservation targets include S. chinensis, D. suweonensis, and H. yangi, which combine narrow niches, restricted ranges, and high climate vulnerability. These findings provide a quantitative basis for climate-adaptive conservation planning for threatened herpetofauna in South Korea. Full article

The fluctuating temperature poses challenges to the survival of amphibians. This study employed two cold-adapted brown frog species, Rana dybowskii and Rana amurensis, from high-latitude cold regions as research models. We explored the mechanism by which contrasting peak daily habitat temperatures affect their physiological function and symbiotic microbial community. The results indicate that these two cold-adapted brown frog species exhibit a common physiological response of enhanced immune capacity and suppressed antioxidant capacity when subjected to elevated temperatures. However, they demonstrate unique coping strategies and physiological regulatory effects on gut microbiota: R. dybowskii activates its immune system by reducing the abundance of Actinobacteria and inhibiting metabolic pathways, but the decrease in Bacteroidetes abundance impairs antioxidant efficacy. On the other hand, R. amurensis experiences impairment of antioxidant function due to the regulatory effects of a significant increase in Proteobacteria and Actinobacteria, a marked decrease in Bifidobacterium, and a decline in gut microbiota α-diversity. For the first time, this study reveals the adaptive mechanisms by which two cold-adapted amphibian species respond to the contrasting peak daily habitat temperatures, providing a scientific basis for understanding how ectotherms react to climate change and for predicting their population dynamics. Full article

Amphibians face a global conservation crisis, driven largely by habitat degradation. Effective and practical strategies for habitat restoration are urgently needed, particularly for Critically Endangered species in human-impacted ecosystems. Telmatobius philippii is a species classified as Critically Endangered by the IUCN. Its habitat is restricted to a few thermal springs in the Ascotán salt flat in Chile. A significant portion of one of these springs, V11, dried up in 2005 due to industrial groundwater withdrawals, leading to the loss of natural refuges and population decline. As part of a recovery plan for this spring we implemented a habitat improvement program by installing artificial refuges (clay tiles, bricks, and rock piles) and monitored their use over a two-year period. The results indicated that the refuges, particularly the clay tiles, were utilized by T. philippii at all life stages (larvae, juveniles, and adults). Refuge occupancy increased over time, reaching 75% by the end of the study, and the presence of eggs and early-stage larvae confirmed successful breeding associated with the artificial structures. This demonstrates the positive effect of artificial refuges as a practical tool for the recovery of Telmatobius populations. To our knowledge, this study provides the first documented case of successful habitat enhancement for this threatened group of high Andean amphibians, offering a replicable strategy for conservation in fragile ecosystems. Full article

Global amphibian populations are declining rapidly and the development of effective cryopreservation protocols for germ cells has become a critical tool in ex situ conservation programs. Post-thaw membrane-integrity viability in four endangered Korean amphibians (Dryophytes suweonensis, Pelophylax chosenicus, Kaloula borealis, and Hynobius yangi) were evaluated. Sperm were cryopreserved using dimethyl sulfoxide (DMSO) or N,N-dimethylformamide (DMF) at 10–30% (v/v) in combination with 0.6 M sucrose, and were frozen at two suspension heights (5 cm vs. 10 cm) above liquid nitrogen. Post-thaw membrane-integrity viability was assessed using a SYBR-14/propidium iodide membrane-integrity assay (LIVE/DEAD kit). Low concentrations of permeating cryoprotectants (CPs) improved membrane-integrity viability, whereas high concentrations led to high toxicity, particularly with DMSO. Across species, DMF produced the highest membrane-integrity viability and the most consistent performance. The cooling rate influenced membrane-integrity viability, with samples frozen at 10 cm exhibiting greater viability, reflecting the balance between intracellular ice formation during rapid cooling and solution effects during slow cooling. Optimal conditions for D. suweonensis were 15% DMSO at 10 cm (86.5% membrane-integrity viability); for P. chosenicus, 10% DMF at 10 cm (75.5%); and for K. borealis, 10% DMSO at 5 cm (81.6% membrane-integrity viability). Hynobius yangi showed modest improvement under 15% DMF at 5 cm (19.7%), although overall membrane-integrity viability was low. ED₅₀ modeling indicated species-specific thresholds requiring low CP concentrations. Sperm cryopreservation outcomes in amphibians are strongly influenced by CP type, concentration, cooling regime, and species physiology. GLM and ED₅₀ modeling provide a methodological framework for refining cryopreservation strategies for non-model, endangered species. Full article

Wetland diversity and associated wildlife is declining globally. The Szaporca Old-Drava oxbow, one of Hungary’s first wetlands designated under the Ramsar Convention, has been threatened by desiccation, prompting the implementation of water replenishment interventions. This study aimed to determine which aquatic vertebrate species can be detected using bottle traps in the oxbow and whether the traps’ efficiency and capture success change following hydrological restoration. Our results showed that the relative frequency of smooth newts caught with bottle traps was 10%, while that of other amphibians (Danube crested newt, common spadefoot toad, edible frog) and fish (European weather loach, European mudminnow, Danube whitefin gudgeon) species did not even reach 1%. Based solely on the relative frequency data of the smooth newt, we found that both the capture efficiency (10.4% vs. 3%) and capture success (17% vs. 7.4%) of bottle traps significantly declined following an increase in water volume in the oxbow. Sex ratio patterns also shifted markedly: in the year of water scarcity, the male-to-female ratio of smooth newt was 2.7:1, whereas during water-abundant conditions it increased to 7:1. Water replenishment raised the water level by nearly one meter, resulting in the partial inundation of terrestrial vegetation and consequent habitat alterations. While water supplementation clearly supports the persistence of rare, protected, strictly protected and endemic aquatic species, our findings highlight the importance of considering hydrological conditions when interpreting the results of long-term monitoring in wetland ecosystems. Full article