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Dinotefuran, a chiral neonicotinoid pesticide, is known to cause endocrine disruption, but the specific impact of its enantiomers remains unclear. Xenopus laevis tadpoles were exposed to varying concentrations of R- and S-dinotefuran (0, 5, and 50 μg/L) for 21 days. Body length and developmental stages were measured, and hormone levels and HPT axis gene expression were analyzed. Molecular docking was performed to evaluate the activation of the thyroid hormone receptor (TRα) by the enantiomers. Dinotefuran exposure significantly decreased body length and delayed developmental stages, indicating developmental toxicity. It reduced T3, T4, and TSH levels, suggesting thyroid endocrine disruption. Dinotefuran increased the mRNA expression of TSH synthesis and receptor genes, likely compensating for lower T4. Changes in iodide uptake and deiodinase gene expression may explain reduced thyroid hormone levels. Molecular docking showed that both R- and S-dinotefuran can directly activate TRα. Additionally, enantioselective differences were observed at the gene expression level, indicating that the developmental toxicity and endocrine disruption effects of the dinotefuran enantiomers differ in their impact on HPT axis regulation. Dinotefuran altered HPT axis gene expression and thyroid hormone levels, causing thyroid endocrine disorders and delayed tadpole metamorphosis, posing a threat to frog populations. [ABSTRACT FROM AUTHOR]

Background: Energetic aspects of neuronal activity have become a major focus of interest given the fact that the brain among all organs dominates the oxygen consumption. At variance with the importance of neuroenergetics, the knowledge about how electrical activity and metabolism is correlated in defined neuronal populations is still rather scarce. Results: We have estimated the ATP consumption in the two physiologically well characterized populations of frog central vestibular neurons, with tonic and phasic firing patterns, respectively. These two distinct groups of neurons jointly process head/body movements detected by semicircular canal and otolith organs in the inner ear. The ATP consumption for maintenance of the resting membrane potential (Vr) and postsynaptic action potential (AP) generation was calculated based on the wealth of previously reported morpho-physiological features of these two neuronal types. Accordingly, tonic vestibular neurons require less ATP across the physiological activity range for these major processes, than phasic vestibular neurons, despite the considerably higher firing rates of the former subtype. However, since both neuronal subtypes are indispensable for the encoding and processing of the entire head/body motion dynamics, the higher energy demand of phasic neurons represents an obvious and necessary price to pay. Although phasic and tonic neurons form the respective core elements of the frequency-tuned vestibular pathways, both cellular components are cross-linked through feedforward and feedback side loops. The prominent influence of inhibitory tonic neurons in shaping the highly transient firing pattern of phasic neurons is cost-intensive and contributes to energy consumption for electrical activity in addition to the already extensive energy costs of signal processing by the very leaky phasic vestibular neurons. Conclusion: Despite the sparse production of action potentials by phasic vestibular neurons, the computation by this neuronal type dominates the ATP expense for processing head/body movements, which might have contributed to the late evolutionary arrival of this central neuronal element, dedicated to the encoding of highly dynamic motion profiles. [ABSTRACT FROM AUTHOR]

We hypothesized that the North American invasive crayfish Procambarus clarkii (Girard, 1852) can negatively affect the populations of native frog species through predation. We conducted three laboratory experiments to examine whether P. clarkii can prey on eggs or larvae of the Japanese native frog Rana japonica Boulenger , 1879: Experiment I crayfish + frog egg in an aquarium without a substrate or aquatic plants, Experiment II crayfish + frog larva in an aquarium without a substrate or aquatic plants, and Experiment III crayfish + frog larva in an aquarium with a substrate and aquatic plants as shelter for the larva. We used three experimental groups of crayfish individuals (small, intermediate, and large size), each of 10 individuals, and simultaneously placed one crayfish individual and one egg or frog larva in the same aquarium for 24 h and checked for predation by the crayfish. We found that 88.9% and 86.7% of eggs and larvae used in Experiments I and II were preyed upon, respectively. Predation rate of frog larvae was still high (77.8%) in Experiment III, suggesting that crayfish can potentially find and prey on frog larvae in nature. Predation on frog eggs or larvae was high regardless of the crayfish body size. Our results indicate that P. clarkii can potentially have a marked effect on the population of R. japonica by preying on eggs and larvae. [ABSTRACT FROM AUTHOR]

Amphibians are continuously exposed to pollutants and anthropogenic stressors in their natural habitats, representing a significant challenge to their survival. This study aimed to quantify the extent of DNA damage caused by chronic industrial and agrochemical surface water pollution in wild populations of the marsh frog (Pelophylax ridibundus). The observed genotoxic effects on the marsh frog DNA, manifesting as abnormalities in erythrocyte nuclei, micronuclei, and DNA strand breaks, demonstrate a clear cause-and-effect relationship with surface water parameters, heavy metals, metalloids, and pesticides. The most prevalent nuclear abnormalities observed were notched and blebbed nuclei and nuclear buds, indicative of chromosomal instability. The significant correlation between cadmium, lead, and copper contamination and the increased frequency of DNA breakage in the marsh frogs from the industrial site indicates that heavy metal contamination has a higher genotoxic potential than pesticide contamination. These findings underscore the vulnerability of amphibians inhabiting heavy metal-contaminated wetlands to genotoxic stress due to their lower tolerance to environmental genotoxins. Therefore, using in situ assays to detect erythrocyte nuclear abnormalities and DNA damage in P. ridibundus could serve as a reliable indicator of environmental quality and provide early detection of anthropogenic pollution. [ABSTRACT FROM AUTHOR]

Currently, the name Gastrotheca splendens is applied to Bolivian montane forest populations of marsupial frogs that have been associated with G. marsupiata and its allies in the past. Because its comparatively large size evoked taxonomic doubts, we re-examined the holotype of Hyla splendens Schmidt, 1857 and extracted and sequenced archival DNA to clarify its identity. Morphological and molecular data revealed H. splendens as being conspecific with Gastrotheca monticola from northwestern Peru. We place Gastrotheca monticola Barbour & Noble, 1920 as a junior synonym of Hyla splendens Schmidt, 1857, regarding the latter a valid species, Gastrotheca splendens (Schmidt, 1857). We furthermore correct its type locality to 'northwestern Peru'. As a result of these findings and the morphological differences observed among the name-bearing types, the Bolivian taxa Gastrotheca lauzuricae De la Riva, 1992 and G. piperata Duellman & Köhler, 2005 are removed from the synonymy of Hyla splendens. Examination of the external morphology and osteology (inferred from micro-CT images) of the holotypes of G. lauzuricae and G. piperata revealed several differences. However, with the data currently available, we are unable to judge whether these differences represent species-specific diagnostic characters or intraspecific variation. We consider G. lauzuricae a valid species and, applying a principle of parsimony of taxonomic changes, provisionally regard G. piperata as its junior synonym pending future investigations. Furthermore, pending further studies, we tentatively continue to consider Gastrotheca coeruleomaculata (Werner, 1899) a valid species occurring in montane forests of the Departamento La Paz, Bolivia. Finally, Leptodactylus andicola Boettger, 1891 is removed from the synonymy of Gastrotheca marsupiata (Duméril & Bibron, 1841) and regarded a nomen dubium based on the morphological characters mentioned in its original description, which are in disagreement with Gastrotheca and argue for affinities with the genus Yunganastes (Strabomantidae). The results of this study highlight the importance of referring to namebearing type specimens when taxonomically revising complex and species-rich groups of organisms. [ABSTRACT FROM AUTHOR]

Temporally variable climates are expected to drive the evolution of thermal physiological traits that enable performance across a wider range of temperatures (i.e. climate variability hypothesis, CVH). Spatial thermal variability, however, may mediate this relationship by providing ectotherms with the opportunity to behaviourally select preferred temperatures (i.e. the Bogert effect). These antagonistic forces on thermal physiological traits may explain the mixed support for the CVH within species despite strong support among species at larger geographical scales. Here, we test the CVH as it relates to plasticity in physiological upper thermal limits (critical thermal maximum—CTmax) among populations of coastal tailed frogs (Ascaphus truei). We targeted populations that inhabit spatially homogeneous environments, reducing the potentially confounding effects of behavioural thermoregulation. We found that populations experiencing greater temporal thermal variability exhibited greater plasticity in CTmax, supporting the CVH. Interestingly, we identified only one site with spatial temperature variability and tadpoles from this site demonstrated greater plasticity than expected, suggesting the opportunity for behavioural thermoregulation can reduce support for the CVH. Overall, our results demonstrate one role of climate variability in shaping thermal plasticity among populations and provide a baseline understanding of the impact of the CVH in spatially homogeneous thermal landscapes. [ABSTRACT FROM AUTHOR]

The northern leopard frog (Lithobates pipiens) has undergone dramatic declines in population size and range over recent decades in western Canada and the United States. In British Columbia, only a single population remains at the Creston Valley Wildlife Management Area. Yet, the continuing viability of this population is uncertain. In this paper, the current genetic structure of northern leopard frog populations in western Canada was assessed using microsatellite markers. Historical samples from the extinct population of Fort Steele in British Columbia were compared with the Creston Valley population to understand changes in population genetic parameters over time. Genotypic data from four populations (Creston Valley, Drain K, Prince Spring, and Cypress Hill) sampled in 2004 and 2019 were compared. To evaluate changes in the genetic diversity of the Creston Valley population over time, allelic richness and expected heterozygosity of the population were compared at three time points using genotypes from 2000, 2004, and 2019. Northern leopard frog populations in western Canada showed high genetic differentiation, with genetic diversity decreasing from east to west. Although there weren't notable changes in genetic parameters between 2004 and 2019, there was evidence of a decline in diversity between 2000 and 2019. The extinct population of Fort Steele had private alleles, while the current Creston Valley population did not, suggesting a genetic bottleneck in the Creston Valley population. Therefore, genetic rescue, specifically for the endangered Creston Valley population, can be considered as an action to support recovery. Additionally, continued genetic monitoring will help in the effective management of the species by providing information on the success of conservation actions. [ABSTRACT FROM AUTHOR]

Simple Summary: The main objective of this study was to provide the first information on the age structure of the critically endangered and endemic frog species, Rana tavasensis, in Türkiye. Age data are important in evaluating the dynamics of populations and effective conservation strategies should be addressed according to age-related parameters (e.g., longevity, mean age, growth rate, and age at maturity). Skeletochronology is an effective method for estimating the ages of amphibians, and using this method, we determined the mean age, longevity, and relationship between age and body size in both males and females of a R. tavasensis population in Çakıroluk, the terra-typica, located in Denizli province, Türkiye. The results of our study provides insights for taking feature measures to protect these frogs, whose number has progressively declined each year due to habitat loss and degradation. This study used skeletochronology to assess the relationships between age and body length among individuals in a population of the Tavas Frog (Rana tavasensis), located in the Çakıroluk plateau, Tavas district, Denizli province. The age varied from 3 to 12 years in both adult males and females. The age was 2 years in two subadult males, while it was 1 year in one juvenile specimen. The mean SVL and age of the adult individuals of the Çakıroluk population were 62.75 mm and 6.70 years in male specimens and 58.04 mm and 6.12 years in female specimens. A positive correlation was found between body size (SVL) and age in adult female and male individuals of the species. Because the number of individuals of the species is rapidly decreasing, species protection measures, based on knowledge related to the age structure and breeding features of these frogs, must be put into action urgently. [ABSTRACT FROM AUTHOR]

Antimicrobial peptides (AMPs) play a fundamental role in the innate defense against microbial pathogens, as well as other immune and non-immune functions. Their role in amphibian skin defense against the pathogenic fungus Batrachochytrium dendrobatidis (Bd) is exemplified by experiments in which depletion of host's stored AMPs increases mortality from infection. Yet, the question remains whether there are generalizable patterns of negative or positive correlations between stored AMP defenses and the probability of infection or infection intensity across populations and species. This study aims to expand on prior field studies of AMP quantities and compositions by correlating stored defenses with an estimated risk of Bd exposure (prevalence and mean infection intensity in each survey) in five locations across the United States and a total of three species. In all locations, known AMPs correlated with the ability of recovered secretions to inhibit Bd in vitro. We found that stored AMP defenses were generally unrelated to Bd infection except in one location where the relative intensity of known AMPs was lower in secretions from infected frogs. In all other locations, known AMP relative intensities were higher in infected frogs. Stored peptide quantity was either positively or negatively correlated with Bd exposure risk. Thus, future experiments coupled with organismal modeling can elucidate whether Bd infection affects secretion/synthesis and will provide insight into how to interpret amphibian ecoimmunology studies of AMPs. We also demonstrate that future AMP isolating and sequencing studies can focus efforts by correlating mass spectrometry peaks to inhibitory capacity using linear decomposition modeling. [ABSTRACT FROM AUTHOR]

Accurately estimating effective population size (Ne) is essential for understanding evolutionary processes and guiding conservation efforts. This study investigates Ne estimation methods in spatially structured populations using a population of moor frog (Rana arvalis) as a case study. We assessed the behaviour of Ne estimates derived from the linkage disequilibrium (LD) method as we changed the spatial configuration of samples. Moor frog eggs were sampled from 25 breeding patches (i.e., separate vernal ponds, ditches or parts of larger fens) within a single population, revealing an isolation‐by‐distance pattern and a local spatial genetic structure. Varying buffer sizes around each patch were used to examine the impact of sampling window size on the estimation of effective number of breeders (Nb). Our results indicate a downward bias in LD Nb estimates with increasing buffer size, suggesting an underestimation of Nb. The observed bias is attributed to LD resulting from including genetically divergent individuals (mixture‐LD) confounding LD due to drift. This emphasises the significance of considering even subtle spatial genetic patterns. The implications of these findings are discussed, emphasising the need to account for spatial genetic structure to accurately assess population viability and inform conservation efforts. This study contributes to our understanding of the challenges associated with Ne estimation in spatially structured populations and underscores the importance of refining methodologies to address population‐specific spatial dynamics for effective conservation planning and management. [ABSTRACT FROM AUTHOR]

Value of information (VoI) analysis is a method for quantifying how additional information may improve management decisions, with applications ranging from conservation to fisheries. However, VoI studies frequently suggest that collecting more data will not substantially improve management outcomes. This often contradicts the intuition of ecologists and managers who usually believe new information is critical for management. This inconsistency is exacerbated by the perception that VoI is a black‐box method. A lack of understanding as to why VoI is usually lower than ecologists expect is hampering on‐ground uptake. There is an urgent need to identify the factors that drive VoI methodology to produce low values.Here, we use a rigorous approach to provide insights into why VoI values are often low. We first derive analytic solutions and upper bounds for a VoI problem with two uncertain states, two actions, and four management outcomes. We show how VoI changes with respect to the benefit (i.e. utility) of implementing actions in each state, and the probability the system is in each state. We apply our formulation to a published frog population management case study and extend the results numerically to 10 million randomly generated larger‐sized problems.Zero VoI occurred half of the time in our two‐action two‐state simulations, corresponding to when one action is best, or equal best, across all states. Even when VoI values were positive, they were typically low. However, on average, VoI tended to increase with the number of states and actions. Our analytic expression for VoI, in the case where VoI is positive, demonstrates that VoI is characterized by the state probabilities and, the utility gaps, that is the difference in utility of deploying each action in each state. Our derived bounds reveal that, in all two‐action two‐state systems, VoI cannot be larger than half the largest utility gap.Our simple, yet powerful, analysis provides precious insight into the important factors that drive VoI analysis. Our work provides an essential stepping stone towards increasing the interpretability of VoI analysis in more complex settings, ultimately empowering managers to use VoI to help inform their decisions. [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]

In order to understand the population abundance and dynamic of crab-eating frog (Fejervarya cancrivora)in the mangrove of Hainan Dongzhaigang National Nature Reserve, 34 line transects were investigated in tidal ditches of mangrove from 2020 to 2022. Further, the risk factors affecting the frog population in the reserve were analyzed, and some suggestions on protection and management were informed. The results showed that crab-eating frogs mainly distributed in the regions of Management Bureau, Daoxue and Sanjiang, but absent in Tashi and Bodu. The population density of crab-eating frog was highest in Sanjiang, then in Daoxue and lowest in Management Bureau. The population density of Sanjiang, Daoxue, Management Bureau were 221. 6 individuals/hm², 164. 7 individuals/hm², 137. 4 individuals/hm² respectively in 2020, which was significantly higher than that in 2022 (151. 2 individuals/hm² in Sanjiang, 144. 8 individuals/hm² in Daoxue and 116. 3 individuals/hm² in Management Bureau) and 2021 (113. 2 individuals/hm² in Sanjiang, 99. 6 individuals/ hm² in Daoxue and 51. 9 individuals/hm² in Management Bureau). The total population of Sanjiang, Daoxue and Management Bureau were 6, 498, 3, 357, 4, 847 respectively from 2020 to 2022. Higher salinity, water pollution, epiphytic oyster and small tidal bare beach area were the main factors leading to the absence of crab-eating frog in Tashi and Bodu. The illegal capture, reduction of breeding habitats and pollution caused by aquaculture ponds are threatening factors to the populations of crab-eating frog. [ABSTRACT FROM AUTHOR]

Frogs play crucial roles in ecosystems as both predator and prey within food webs. The decline in their populations is attributed, in part, to modern, intensive rice farming practices. In the Tajima region of Hyogo Prefecture, Japan, a subset of farmers has embraced a "white stork friendly farming" (WSFF) method since 2003, which promotes environment-friendly rice production to preserve and restore biodiversity while aiding the reintroduction of the Oriental White Stork (Ciconia boyciana) into the ecosystem. Here, we hypothesize that the WSFF method has a positive impact on the conservation of black-spotted pond frog (Pelophylax nigromaculatus) populations inhabiting paddy fields. To test this hypothesis, we evaluated the influence of the WSFF method on the population density of P. nigromaculatus. Using a line transect method, we identified and quantified individual frogs observed on the paddy field levees in June 2016. Subsequently, we analyzed the effects of rice production using the WSFF method and land-use factors on the frogs' population density. Our findings indicate that P. nigromaculatus population density increased with the expansion of paddy-field areas managed under the WSFF method within a 100 m radius of the paddy-field center. These results suggest that rice production following the WSFF method has a positive impact on the conservation of this frog species. [ABSTRACT FROM AUTHOR]

Two water frog species: the pool frog Pelophylax lessonae (L) and the marsh frog P. ridibundus (R) occur sympatrically in Central Europe and form mixed populations (genetic systems) with their hybrid, the edible frog P. esculentus (E). The aim of the study was to assess the species composition of water frogs in urban and rural populations and compare our current findings with the results of previous studies. We surveyed the same sites that were investigated by Berger et al. in 1962–1970 (Poznań, urban landscape) and 1977–1997 (Dezydery Chłapowski Landscape Park, rural landscape). Because some ponds surveyed in the past were destroyed or dried-up, we also explored others located in the adjacent areas. We captured frogs during breeding seasons 2020 and 2021 and identified them by the nuclear marker gene SAI-1. We found three types of populations in the urban area: R-E, E-E and R-E-L and four in the rural area: R-E, L-E, E-E and R-E-L. Compared to the historical data, we found a drastic decrease in the frequency of P. lessonae in urban and rural landscapes: from 89.1% and 68% to 2.7% and 1.8%, respectively. At the same time, the frequency of P. ridibundus increased from 2.2% and 0.1% to 40% and 29.6%, respectively. A similar pattern was found for P. esculentus whose frequency increased from 8.7% and 31.9% to 57.3% and 68.6%, respectively. Additionally, we confirmed the presence of a cryptogenic Balkan water frog, P. kurtmuelleri, which was recently discovered in south-western Poland. The frequency of SAI-1 allele specific for this taxon reached 7.3%. The patterns found in both types of landscapes are in line with the current situation of both parental species in Europe. Such dynamic changes show the need for long-term monitoring of the population compositions of water frogs, what is crucial for their conservation management. [ABSTRACT FROM AUTHOR]

Population systems in which all three taxa of the Pelophylax esculentus complex coexist are rare and in Serbia can only be found along the Danube. Although several studies describe the diet in populations with only one taxon, there is a lack of data from mixed populations. We studied the diet in mixed populations of edible frogs at three sites for three years. We collected gut contents from 221 adult frogs using the stomach flushing method and identified 1,477 prey items. The diet consisted mainly of insects (88%). For all three taxa, the most frequently consumed prey groups were Hymenoptera (28%), Coleoptera (18%), Lepidoptera (17%) and Diptera (11%). Larger prey (in terms of length and volume) was mainly consumed by P. ridibundus, followed by P. esculentus. The smallest prey were mainly consumed by P. lessonae. However, P. ridibundus consumed fewer prey items than P. lessonae. No significant difference was found between the taxa in the staple diet, while there were differences in the less abundant prey categories, especially between P. ridibundus and P. lessonae. The narrowest trophic niche width was observed in P. lessonae, followed by P. esculentus, and the widest in P. ridibundus. Our results suggest that the diet of the three taxa is diverse and consists of a large number of invertebrate groups. However, the diet was locality-specific, with the dominance of different prey groups in different localities depending on habitat characteristics. These results confirm our expectation that the frogs of the Pelophylax esculentus complex follow an opportunistic foraging strategy, as predicted by optimal foraging theory. [ABSTRACT FROM AUTHOR]

Insights from conservation genomics have dramatically improved recovery plans for numerous endangered species. However, most taxa have yet to benefit from the full application of genomic technologies. The mountain yellow-legged frog species complex, Rana muscosa and Rana sierrae, inhabits the Sierra Nevada mountains and Transverse/Peninsular Ranges of California and Nevada. Both species have declined precipitously throughout their historical distributions. Conservation management plans outline extensive ongoing recovery efforts but are still based on the genetic structure determined primarily using a single mitochondrial sequence. Our study used two different sequencing strategies – amplicon sequencing and exome capture – to refine our understanding of the population genetics of these imperiled amphibians. We used buccal swabs, museum tissue samples, and archived skin swabs to genotype frog populations across their range. Using the amplicon sequencing and exome capture datasets separately and combined, we document five major genetic clusters. Notably, we found evidence supporting previous species boundaries within Kings Canyon National Park with some exceptions at individual sites. Though we see evidence of genetic clustering, especially in the R. muscosa clade, we also found evidence of some admixture across cluster boundaries in the R. sierrae clade, suggesting a stepping-stone model of population structure. We also find that the southern R. muscosa cluster had large runs of homozygosity and the lowest overall heterozygosity of any of the clusters, consistent with previous reports of marked declines in this area. Overall, our results clarify management unit designations across the range of an endangered species and highlight the importance of sampling the entire range of a species, even when collecting genome-scale data. [ABSTRACT FROM AUTHOR]

The excessive activation of frog eggs, referred to as overactivation, can be initiated by strong oxidative stress, leading to expedited calcium-dependent non-apoptotic cell death. Overactivation also occurs spontaneously, albeit at a low frequency, in natural populations of spawned frog eggs. Currently, the cytological and biochemical events of the spontaneous process have not been characterized. In the present study, we demonstrate that the spontaneous overactivation of Xenopus frog eggs, similarly to oxidative stress- and mechanical stress-induced overactivation, is characterized by the fast and irreversible contraction of the egg's cortical layer, an increase in egg size, the depletion of intracellular ATP, a drastic increase in the intracellular ADP/ATP ratio, and the degradation of M phase-specific cyclin B2. These events manifest in eggs in the absence of caspase activation within one hour of triggering overactivation. Importantly, substantial amounts of ATP and ADP leak from the overactivated eggs, indicating that plasma membrane integrity is compromised in these cells. The rupture of the plasma membrane and acute depletion of intracellular ATP explicitly define necrotic cell death. Finally, we report that egg overactivation can occur in the frog's genital tract. Our data suggest that mechanical stress may be a key factor promoting egg overactivation during oviposition in frogs. [ABSTRACT FROM AUTHOR]

Simple Summary: Rana temporaria is one of the most widespread Palearctic brown frogs, with two main genetic clades in Europe, geographic spatial pattern of which is insufficiently known. We analyzed samples from the understudied western and central Balkans to evaluate the haplotype diversity of widely used 16SrRNA and MT-CYTB mitochondrial gene sequences and to recognize the contour of a possible contact zone between the main clades. The results revealed a suture zone between the Western and Eastern Clades in the central part of the Balkan Peninsula. Overall, haplotype diversity in the western and central Balkans sample is high. Harboring both main genetic clades of R. temporaria qualifies the Balkan Peninsula as another important center of species' genetic diversity, as well as rich in unique haplotypes. Rana temporaria is one of the most widespread Palearctic brown frogs. We aimed to clarify distribution pattern of two main genetic clades in the understudied Balkan peninsula by using 16SrRNA and MT-CYTB sequences, already widely applied in analyses of populations from other parts of Europe, while focusing on the broad area along the Morava river (central Balkans) as a known gap in the species distribution. Additionally, we were interested in revealing the extent of haplotype diversity within the main genetic clades in the Balkans, particularly around the supposed suture zone. The results revealed a suture zone between the Western and Eastern Clades in the central part of the Balkan Peninsula. This indicated the existence of a historical barrier between the Balkan Mountain Belt and geographically close mountains surrounding the Vlasina Plateau (Rhodope/Serbian–Macedonian Massif). The overall observed haplotype diversity in populations of R. temporaria from the Balkan Peninsula seems high. Harboring both main genetic clades of R. temporaria qualifies the Balkan Peninsula as another important center of species' genetic diversity, as well as rich in unique haplotypes. This points out the necessity of applying conservation measures focused on the common European frog populations and habitats in this part of the species' distribution area. [ABSTRACT FROM AUTHOR]

Variable harlequin frogs Atelopus varius have declined significantly throughout their range as a result of infection with the fungal pathogen Batrachochytrium dendrobatidis (Bd). The Panama Amphibian Rescue and Conservation Project maintains an ex situ population of this Critically Endangered species. We conducted a release trial with surplus captive-bred A. varius individuals to improve our ability to monitor frog populations post-release, observe dispersal patterns after freeing them into the wild and learn about threats to released frogs, as well as to determine whether natural skin toxin defences of frogs could be restored inside mesocosms in the wild and to compare Bd dynamics in natural amphibian communities at the release site vs a non-release site. The 458 released frogs dispersed rapidly and were difficult to re-encounter unless they carried a radio transmitter. No frog was seen after 36 days following release. Thirty frogs were fitted with radio transmitters and only half were trackable by day 10. Tetrodotoxin was not detected in the skins of the frogs inside mesocosms for up to 79 days. Bd loads in other species present at sites were high prior to release and decreased over time in a pattern probably driven by weather. No differences were observed in Bd prevalence between the release and non-release sites. This trial showed that refinements of our methods and approaches are required to study captive Atelopus frogs released into wild conditions. We recommend continuing release trials of captive-bred frogs with post-release monitoring methods, using an adaptive management framework to advance the field of amphibian reintroduction ecology. [ABSTRACT FROM AUTHOR]

Sex chromosome turnover is the transition between sex chromosomes and autosomes. Although many cases have been reported in poikilothermic vertebrates, their evolutionary causes and genetic mechanisms remain unclear. In this study, we report multiple transitions between the Y chromosome and autosome in the Japanese Tago's brown frog complex. Using chromosome banding and molecular analyses (sex-linked and autosomal single nucleotide polymorphisms, SNPs, from the nuclear genome), we investigated the frogs of geographic populations ranging from northern to southern Japan of two species, Rana tagoi and Rana sakuraii (2n = 26). Particularly, the Chiba populations of East Japan and Akita populations of North Japan in R. tagoi have been, for the first time, investigated here. As a result, we identified three different sex chromosomes, namely chromosomes 3, 7, and 13, in the populations of the two species. Furthermore, we found that the transition between the Y chromosome (chromosome 7) and autosome was repeated through hybridization between two or three different populations belonging to the two species, followed by restricted chromosome introgression. These dynamic sex chromosome turnovers represent the first such findings in vertebrates and imply that speciation associated with inter- or intraspecific hybridization plays an important role in sex chromosome turnover in frogs. [ABSTRACT FROM AUTHOR]

This article, published in the Journal of Raptor Research, discusses the predation of a Titicaca water frog by a Mountain Caracara in Peru. The Mountain Caracara is an opportunistic predator and scavenger that typically feeds on lizards, birds, arthropods, refuse, and carrion. This observation of the caracara preying on a frog contributes to a better understanding of its food habits. The Titicaca water frog is an endangered species, and this study provides valuable insights into predator-prey interactions involving this iconic frog species in the region. [Extracted from the article]

The American bullfrog Lithobates catesbeianus is a well-known invasive alien species recorded in over 40 countries and islands. It is necessary to elucidate their seasonal emergence and habitat water body characteristics for implementing efficient eradication activities. Sado Island, Japan, is home to several endemic and rare species, including the endangered Sado wrinkled frogs (Glandirana susurra) that are concerned to be negatively impacted by invasive American bullfrogs. Here, we surveyed 41 ponds for invasive American bullfrogs over the period preceding emergence to the start of oviposition to determine their seasonal emergence and habitat pond use. As in previous studies, we observed initiations of their post-hibernation activities such as emergence, mating call, and oviposition in that order as air temperature increased, and those activities were thought to begin as late as late-April, mid-May, and mid-July, respectively on Sado Island. For their habitat preferences, we confirmed that they mainly inhabit relatively deep ponds surrounded by rice paddy fields. Our results were broadly consistent with those of previous studies, with respect to the seasonal emergence and habitat pond characteristics of American bullfrogs on Sado Island. Since our results suggest an overlap in habitat and pond usage season between American bullfrogs and Sado wrinkled frogs, we highly recommend implementing bullfrog eradication activities to conserve the Sado wrinkled frog population. This study provided the basic ecological information for selecting appropriate seasons and ponds for implementing bullfrog eradication activities. [ABSTRACT FROM AUTHOR]

Amphibians are among the most sensitive taxa to climate change, and species inhabiting arid and semiarid landscapes at the extremes of their range are especially vulnerable to drought. The Jack Creek, Oregon, USA, population of Oregon spotted frogs (Rana pretiosa) faces unique challenges because it occupies the highest elevation site in the species' extant range and one that has been transformed by loss of American beavers (Castor canadensis), which historically maintained open water. We evaluated the effects of drought mitigation (addition of excavated ponds) on relationships between local and regional water availability, inactive legacy beaver dams, and Oregon spotted frog population dynamics in the Jack Creek system. We conducted egg mass surveys and capture‐mark‐recapture sampling at a treatment reach with excavated ponds and 3 reference reaches over 13 years; surveys spanned a period before and after pond excavation at the treatment and 1 primary comparison reference reach. We analyzed data using a combination of robust design capture‐mark‐recapture estimators and generalized linear mixed models to characterize population dynamics. Adult Oregon spotted frog survival was approximately 19.5% higher at the treatment reach than the primary reference reach during the study period. Annual survival was most strongly associated with late summer vegetation greenness, a proxy for water availability, and males had higher survival than females. Among the 4 study reaches, the treatment reach consistently had higher late summer vegetation greenness, and the hydrology functioned more independently of regional precipitation patterns relative to the reference reaches; however, these dynamics were not linked to pond excavation. Breeding was concentrated in 2 legacy beaver ponds that were deepened by excavation during the study compared to an unexcavated beaver pond, 2 excavated ponds without legacy beaver dams, and 9 reference ponds. These results point to the benefit of enhancing existing beaver structures and indicate that management actions aimed at maintaining surface water for breeding in spring and saturated soils and ponded water for adults in late summer would benefit this unique population of Oregon spotted frogs in the face of drought. [ABSTRACT FROM AUTHOR]

Freshwater vertebrate predators can exert trophic control over aquatic and littoral communities. Among these predators, post‐metamorphic anurans exhibit a biphasic trophic spectrum by foraging in both terrestrial and aquatic habitats. Many studies have described their diet through the classical taxonomic classification of prey. However, these singular diet habits imply a complex, time‐dependent, realised trophic niche in which predation pressure occurs over many consumers that fill diverse functional roles throughout the aquatic and terrestrial interface of ponds. Among anurans, marsh frogs (Pelophylax ridibundus) have been introduced outside their range in many countries and are now invading nationwide areas, particularly in western Europe. Focusing on their foraging specificities will therefore further the understanding of the trophic role of these alien taxa in pond environments that are highly colonised.We collected stomach contents from 761 marsh frogs from introduced populations in 19 ponds in southern France once a month over 4 months of their active period in the spring. The populations of marsh frogs were studied in a geographic area that was devoid of native water frogs and their origin tracks back as far as south‐eastern Europe (i.e., more than 1,000 km from the studied sites, as evidenced previously by genetic analyses).Marsh frogs exhibited generalist and opportunistic feeding strategies. The trophic niche was strongly asymmetrical and broader in the terrestrial environment than in the aquatic environment. However, predation occurred in communities of large freshwater macroinvertebrates and amphibians. Whereas the composition of the terrestrial diet exhibited strong seasonal variations, predation pressure was continuously exerted on the same aquatic organisms over time. Primary consumers and consumers at higher trophic levels frequenting aquatic benthic, vegetated, pelagic, and surface microhabitats were preyed upon, underlying the multidimensional extent of the predation spectrum.The diversified feeding strategies of alien marsh frogs highlight the extent of potential ecological control by predation on pond communities. Because of their wide trophic niche, they exert predation pressure on most pond organisms, triggering possible top‐down control of the overall aquatic communities.Our results show that the integration of the functional traits and microhabitats of consumed prey may aid in a better understanding of how predation by anurans may target specific components of pond communities. More particularly, this study raises concerns about the predatory role of introduced anurans in the context of biological invasions. [ABSTRACT FROM AUTHOR]

Ectothermic animals like amphibians have unique life histories that are impacted by a variety of eco-geographical variables. In this study, the impacts of altitude, which is one of the most frequently used parameters, were examined concerning the age structure, age upon attaining sexual maturity, sexual dimorphism, and growth of two populations of marsh frogs (Pelophylax ridibundus) living at different elevations. The maximum lifespan was 13 years, the highest lifespan ever recorded for P. ridibundus, in the high-altitude population (Sultansazlığı), while it was eight years in the low-altitude population (Ulubağ). In this study, we estimated that individuals living at low altitudes generally reach sexual maturity at the end of their 2nd or 3th year, while individuals living at high altitudes reach sexual maturity approximately one year later. Our results indicated that the population living in the high-altitude site has an average larger body size, higher age, and body weight compared to the population living in the low-altitude site. [ABSTRACT FROM AUTHOR]

Frog population declines have already been observed in the central Amazon even for common species that are considered not to be in danger of extinction. The Amazon is close to its limit of tolerated deforestation, and parts of the forest have already been modified by climate change, which raises questions about how the fauna in these areas would adapt to climate changes by the middle and the end of this century. In this study we used population density data on seven species of Amazonian frogs and analyzed the relationship between the activity of these species and temperature, precipitation, and relative humidity. We also used the least-squares method with logarithmic models to assess whether climate change projected by the Intergovernmental Panel on Climate Change (IPCC) would be an indicator of the population dynamics of these species. Our results suggest that even common species may be may experience population declines and extinction in the next decades due to climate changes. [ABSTRACT FROM AUTHOR]

Using skeletochronology, we assessed the relationships of age and body size (SVL) in individuals from a population of the agile frog Rana dalmatina near the village of Özyurt, North-western Türkiye. The mean age and SVL of adult frogs were 4.50 ± 0.38 years and 61.54 ± 1.31 mm (6.46 ± 0.33 years and 67.86 ± 1.00 mm in females and 3.00 ± 2.71 years and 56.70 ± 1.26 mm in males, respectively). Intersexual differences in body size were female-biased (SSD = 0.196) while the age ranged between 4-8 years in females and 2-6 years in males. There was a positive correlation between body size and age (i.e., larger frogs were older) in both female and male individuals of this species. [ABSTRACT FROM AUTHOR]

The article discusses the successful use of Itraconazole to manage Batrachochytrium dendrobatidis outbreaks in ex-situ frog colonies in Argentina, focusing on the El Rincon Stream Frog, a Critically Endangered species. The study details the treatment protocol, including dose and schedule, to combat the chytrid fungus infection that caused mass mortality events in the frog colony. The research highlights the importance of preemptive biosecurity measures and the need for further experiments to determine the most effective treatment for endangered amphibian species in ex-situ settings. [Extracted from the article]

Background: Mosquitoes are the deadliest organisms in the world, killing an estimated 750,000 people per year due to the pathogens they can transmit. Mosquitoes also pose a major threat to other vertebrate animals. Culex territans is a mosquito species found in temperate zones worldwide that feeds almost exclusively on amphibians and can transmit parasites; however, little is known about its ability to transmit other pathogens, including fungi. Batrachochytrium dendrobatidis (Bd) is a topical pathogenic fungus that spreads through contact. With amphibian populations around the world experiencing mass die-offs and extinctions due to this pathogen, it is critical to study all potential modes of transmission. Because Cx. territans mosquitoes are in contact with their hosts for long periods of time while blood-feeding, we hypothesize that they can transmit and pick up Bd. Methods: In this study, we first assessed Cx. territans ability to transfer the fungus from an infected surface to a clean one under laboratory conditions. We also conducted a surveillance study of Bd infections in frogs and mosquitoes in the field (Mountain Lake Biological station, VA, USA). In parallel, we determined Cx. territans host preference via blood meal analysis of field caught mosquitoes. Results: We found that this mosquito species can carry the fungus to an uninfected surface, implying that they may have the ability to transmit Bd to their amphibian hosts. We also found that Cx. territans feed primarily on green frogs (Rana clamitans) and bullfrogs (Rana catesbeiana) and that the prevalence of Bd within the frog population at our field site varied between years. Conclusions: This study provides critical insights into understanding the role of amphibian-biting mosquitoes in transmitting pathogens, which can be applied to disease ecology of susceptible amphibian populations worldwide. [ABSTRACT FROM AUTHOR]

Vocalization, visual and chemical signals are courtship behaviours of anurans that may expose them to the risk of predation. Here, we described a predation event in which a population of the torrent frog Hylodes cardosoi was in intense courtship behaviour and one individual was caught by a specimen of the pitviper Bothrops jararaca. The predation event was recorded in a region of Atlantic Forest, Paraná, Brazil. We hypothesized that the pitviper was ambush hunting and captured a female frog that was attracted by the vocalization of a nearby male. Predatory interactions are important ecological factors driving the evolution and population size of both prey and predator. This report increases the prey richness described for B. jararaca and also extends the known geographic distribution of H. cardosoi. Our observation contributes to knowledge of the natural history of the species involved. [ABSTRACT FROM AUTHOR]

The marsh frog Pelophylax ridibundus has an extensive distribution range owing to a variety of adaptations that contribute to the development of tolerance to multiple environmental physicochemical factors. Of particular interest are its adaptations to different oxygen levels under mid- and high-altitude conditions. In this work, we carried out a comparative analysis of lactate dehydrogenase (LDH) kinetic parameters in the liver and skeletal muscles of the marsh frogs inhabiting lowland and highland areas of Dagestan. Animals, caught in their natural habitats, had the liver and gastrocnemius muscle isolated and frozen in liquid nitrogen. LDH activity was assayed in the mitochondria-free cytosolic fraction of tissue homogenates, obtained by differential centrifugation. Cytosolic LDH activity was significantly higher in the tissues of highland frogs, namely by 42.4% in the muscles and 2.38 times in the liver (p < 0.05). A high catalytic efficiency of LDH was provided due to significant changes in the enzyme's catalytic parameters, namely an increase in Vmax (by 50.9% in muscles and 70% in the liver, p < 0.05) and a decrease in Km (by 45.9% in muscles and 69% in the liver, p < 0.05). The larger difference between LDH activity in the liver of and lowland frog populations suggests that LDH sensitivity to changes in oxygen tension is higher in the liver than in skeletal muscles. The vector of some other LDH kinetic parameters (Ki, Sopt, Δ) in the liver of highland frogs is quite opposite to that in skeletal muscles. A high activity and modifications of LDH catalytic properties in tissues of the marsh frogs inhabiting highland areas may play an important role in the adaptation of these animals to oxygen deficiency. [ABSTRACT FROM AUTHOR]

Peptides released on frogs' skin in a stress situation represent their only weapon against micro-organisms and predators. Every species and even population of frog possesses its own peptidome being appropriate for their habitat. Skin peptides are considered potential pharmaceuticals, while the whole peptidome may be treated as a taxonomic characteristic of each particular population. Continuing the studies on frog peptides, here we report the peptidome composition of the Central Slovenian agile frog Rana dalmatina population. The detection and top-down de novo sequencing of the corresponding peptides was conducted exclusively by tandem mass spectrometry without using any chemical derivatization procedures. Collision-induced dissociation (CID), higher energy collision-induced dissociation (HCD), electron transfer dissociation (ETD) and combined MS3 method EThcD with stepwise increase of HCD energy were used for that purpose. MS/MS revealed the whole sequence of the detected peptides including differentiation between isomeric Leu/Ile, and the sequence portion hidden in the disulfide cycle. The array of the discovered peptide families (brevinins 1 and 2, melittin-related peptides (MRPs), temporins and bradykinin-related peptides (BRPs)) is quite similar to that of R. temporaria. Since the genome of this frog remains unknown, the obtained results were compared with the recently published transcriptome of R. dalmatina. [ABSTRACT FROM AUTHOR]

Sexually dimorphic body colouration can serve to signal quality in vertebrates, but less is known about its importance in amphibians when compared to some other groups. The green frog (Lithobates clamitans) is a common anuran of aquatic habitats in eastern North America. In adults of both sexes, the dorsal abdomen is green or brown, and the ventral abdomen usually white. In contrast, throat colouration is sexually dimorphic; adult male throats are usually bright yellow in colour, whereas females and some males express white throats. We assessed body colouration in males and females from a population in Georgia, USA using spectrophotometry to quantify variation in these features and determine if hidden dimorphism was present. We then asked whether this spectral variation correlated with aspects of phenotype linked to fitness in anurans. Male throats were higher in Green-Yellow Chroma and lower in UV Chroma than those of females, but the sexes did not differ in ventral or dorsal abdominal colour. Male SVL was related to ventral abdominal colouration; larger males tended to have ventral abdomens with longer-wavelength Hue and reduced Green-Yellow Chroma compared to smaller males. However, throat or dorsal abdominal colouration was unrelated to any morphometric trait examined in either sex. Overall, variation in male throat and abdominal colour was only weakly related to indices of male quality; instead, we hypothesize that the persistence of white-throated males in populations throughout the range of green frogs is related to the presence of sex-reversed males and intersex individuals recently described from other populations. [ABSTRACT FROM AUTHOR]

The study of the peculiarities of energy metabolism in populations of the marsh frog Pelophylax ridibundus from several reservoirs of the Kamchatka Peninsula with different temperature regimes revealed the temperature compensation of this parameter in tadpoles. The linear dependence of the tadpoles' metabolic rate on the average annual temperature of habitat was shown. It was found that stable inherited differences in the intensity of tadpoles' metabolism were formed in 30–20 years from the moment of the first introduction of the species into the reservoirs of Kamchatka. An assumption is made about the limit of adaptive diapason of the species for the development stage 39–40 of tadpoles of the marsh frog. [ABSTRACT FROM AUTHOR]

The genus Pelophylax has the most controversial taxonomy of any group of western Palearctic frogs. The taxonomic status of the Pelophylax ridibundus sensu lato from Iran is unclear and many populations of this marsh frog have not been examined. Here, we investigate cytogenetic and morphological variation in populations of this species from western and southwestern Iran. The morphometric results revealed that the frogs from these two areas can be largely distinguished in discriminate function analyses. All frogs are diploid and have 2N=26 chromosomes with five large pairs and eight small pairs of chromosomes. These chromosomes are metacentric, submetacentric and subtelocentric. All frogs have three or four pairs of subtelocentric chromosomes. The 6th and 13th pairs of chromosomes are subtelocentric in all western populations, but the position of the third subtelocentric chromosome pair varies. In south-western populations (Bushehr and Deylam regions) the 8th, 9th, and 13th >pairs of chromosomes are subtelocentric, but frogs from Bushehr have one more pair of subtelocentric chromosomes (11th). The second pair of large chromosomes in western populations is submetacentric, but in southwestern populations, the second pair of large chromosomes is metacentric. These differences in the type of chromosomes of P. ridibundus, especially in the presence, absence and number of subtelocentric chomosomes, suggest that the taxonomy of Pelophylax in Iran requires further investigation. [ABSTRACT FROM AUTHOR]

Given the speed at which humans are changing the climate, species with high degrees of endemism may not have time to avoid extinction through adaptation. We investigated through teleconnection analysis the origin of rainfall that determines the phylogenetic diversity of rainforest frogs and the effects of microclimate differences in shaping the morphological traits of isolated populations (which contribute to greater phylogenetic diversity and speciation). We also investigated through teleconnection analysis how deforestation in Amazonia can affect ecosystem services that are fundamental to maintaining the climate of the Atlantic rainforest biodiversity hotspot. Seasonal winds known as flying rivers carry water vapor from Amazonia to the Atlantic Forest, and the breaking of this ecosystem service could lead Atlantic Forest species to population decline and extinction in the short term. Our results suggest that the selection of morphological traits that shape Atlantic Forest frog diversity and their population dynamics are influenced by the Amazonian flying rivers. Our results also suggest that the increases of temperature anomalies in the Atlantic Ocean due to global warming and in the Amazon forest due to deforestation are already breaking this cycle and threaten the biodiversity of the Atlantic Forest hotspot. [ABSTRACT FROM AUTHOR]

Semi-aquatic European water frogs (Pelophylax spp.) harbour rich helminth infra-communities, whose effects on host population size in nature are poorly known. To study top-down and bottom-up effects, we conducted calling male water frog counts and parasitological investigations of helminths in waterbodies from different regions of Latvia, supplemented by descriptions of waterbody features and surrounding land use data. We performed a series of generalized linear model and zero-inflated negative binomial regressions to determine the best predictors for frog relative population size and helminth infra-communities. The highest-ranked (by Akaike information criterion correction, AICc) model explaining the water frog population size contained only waterbody variables, followed by the model containing only land use within 500 m, while the model containing helminth predictors had the lowest rank. Regarding helminth infection responses, the relative importance of the water frog population size varied from being non-significant (abundances of larval plagiorchiids and nematodes) to having a similar weight to waterbody features (abundances of larval diplostomids). In abundances of adult plagiorchiids and nematodes the best predictor was the host specimen size. Environmental factors had both direct effects from the habitat features (e.g., waterbody characteristics on frogs and diplostomids) and indirect effects through parasite-host interactions (impacts of anthropogenic habitats on frogs and helminths). Our study suggests the presence of synergy between top-down and bottom-up effects in the water frog–helminth system that creates a mutual dependence of frog and helminth population sizes and helps to balance helminth infections at a level that does not cause over-exploitation of the host resource. [ABSTRACT FROM AUTHOR]

The patterns of isolation by distance (IBD) entailing increased genetic differentiation among populations have aroused extensive concerns for evolutionary biologists. Although the IBD may act on spatial processes contributing to the genetic differentiation among populations in anuran species, the factors shaping the IBD of frogs among populations in natural systems are largely unknown. Here, we studied the genetic differentiation among six populations with 24 individuals of the spotted‐leg treefrog along a latitudinal gradient (1860.31 km) based on 1020 single nucleotide polymorphisms from restriction site‐associated DNA sequencing. The results showed that the genetic diversity differed significantly among populations and that the insular populations had higher genetic diversity than the mainland populations. Furthermore, we also found a significant genetic differentiation among populations (FST = 0.277) and no sign of inbreeding (FUNI = −0.145). The IBD was detected for all populations, and a higher degree of the IBD was indicated when controlling for the effects of the isolation between Hainan and mainland populations caused by the Qiongzhou Strait. Our findings suggest that the form of the Qiongzhou Strait plays a key role in shaping the genetic diversity and population differentiation in treefrogs. [ABSTRACT FROM AUTHOR]

The use of translocations for conservation management has increased in frequency over recent decades. Though many early translocations were carried out as one-off management exercises, the need to test release strategies and gain knowledge in order to improve future reintroductions has been recognised. This study examined both the movements and survival of 101 Leiopelma hamiltoni (Anura: Leiopelmatidae) translocated to Long Island, New Zealand, and the response of the source population on Te Pākeka/Maud Island to the removal of a discrete subset of frogs. An experimental approach was taken to test whether familiarity would improve anchoring to the site and discourage homing and dispersal post translocation. Frogs translocated with their neighbours did not stay with those individuals and those that were released in a random pattern did not move towards their former Maud Island neighbours. While initial movements were significantly oriented to the bearing of Maud Island, after several months this had changed to indicate that the frogs moved in a downhill direction. Capture-recapture abundance estimates suggest a decline in the population of translocated frogs during the 46 months post-release and follow up surveys 10-13 years post-release confirm that this translocation failed. Capture-recapture abundance estimates suggest that the 240 m² grid emptied of frogs (i.e. the source population) took one year to return to pre-translocation densities. There is little doubt that translocations will continue to be an important tool for the conservation management of leiopelmatid frogs in New Zealand and for amphibians worldwide. However, a commitment to post-release monitoring, use of methods that allow for causes of failure to be assessed, and testing release strategies is imperative to informing methods and improving the success rates of future translocations. [ABSTRACT FROM AUTHOR]

Control of introduced predators is part of the management strategy for many conservation programs. However, when such programs are designed to protect a single species, the benefits to sympatric native species are usually not assessed. We used site occupancy modelling to investigate whether predator control implemented to protect a native bird species (North Island kōkako) in the Hūnua Ranges, New Zealand also benefits the sympatric native Hochstetter's frog population. We hypothesised this benefit is possible because both native species are vulnerable to introduced mammalian predators that are targeted by control measures. Model results indicate that the predator control history of sites was the only factor to exhibit a strong and consistent relationship with occupancy by frogs. Under a range of realistic model scenarios, the probability of occupancy by juvenile, subadult, and adult frogs was consistently higher at sites that receive intensive predator management. Relationships between occupancy probability and other site factors (number of refugia, air temperature) existed but were inconsistent among frog age classes and either occurred independent of predator control history or appear less biologically relevant than predator control. The results support the notion that predator control designed to protect North Island kōkako in the Hūnua Ranges also benefits the Hochstetter's frog population. [ABSTRACT FROM AUTHOR]

Predation by introduced mammals is considered a primary threat to New Zealand's native frog populations. Rats are known predators of the terrestrial Archey's frog (Leiopelma archeyi), New Zealand's smallest Leiopelmatid frog. During a 12 year study in Whareorino Conservation Area, we investigated effects of sustained rat control on survival, number of independent juveniles per adult, and abundance of Archey's frog. Frogs were monitored following a capture-recapture robust design at four grids, split between a 300- ha 'nontreatment' area and a 300-ha rat control 'treatment' area. Low rat abundances were achieved in the treatment area for much of the study (rat tracking index threshold: < 10%), although, mouse abundances were higher at times there. Adult frog survival rates were greater in treatment (0.74-0.78) compared to nontreatment (0.53-0.55) areas, indicating rat suppression reduces adult frog mortality; however, juvenile and subadult frog survival was lower in treatment (0.03-0.27) than nontreatment areas (0.26-0.61). This may be due to increased vulnerability of smaller frogs to other predators e.g. mice. Population modelling showed ongoing rat suppression has a positive effect on the rate of independent juveniles produced per adult frog and on adult abundance over time, revealing a significant increase in frog abundance in treatment (annual rate of increase, adult frogs: 10.75, 95%; CI [4.62, 17.24]) compared to nontreatment areas where frogs declined (annual rate of decline, adult frogs: -5.73, 95% CI [-10.95, -0.21]). We show that suppressing rat populations is successful for frog population management at Whareorino Conservation Area. However, rat control alone may not be sufficient to recover depleted populations elsewhere or grow newly translocated populations on the mainland. We recommend further work to substantiate the above findings and research to investigate both the impact of mice on native frogs and elucidate age class dependant parameters for Leiopelmatid frogs in mainland and island populations. [ABSTRACT FROM AUTHOR]

Multifarious sources of selection shape visual signals and can produce phenotypic divergence. Theory predicts that variance in warning signals should be minimal due to purifying selection, yet polymorphism is abundant. While in some instances divergent signals can evolve into discrete morphs, continuously variable phenotypes are also encountered in natural populations. Notwithstanding, we currently have an incomplete understanding of how combinations of selection shape fitness landscapes, particularly those which produce polymorphism. We modelled how combinations of natural and sexual selection act on aposematic traits within a single population to gain insights into what combinations of selection favours the evolution and maintenance of phenotypic variation. With a rich foundation of studies on selection and phenotypic divergence, we reference the poison frog genus Oophaga to model signal evolution. Multifarious selection on aposematic traits created the topology of our model's fitness landscape by approximating different scenarios found in natural populations. Combined, the model produced all types of phenotypic variation found in frog populations, namely monomorphism, continuous variation and discrete polymorphism. Our results afford advances into how multifarious selection shapes phenotypic divergence, which, along with additional modelling enhancements, will allow us to further our understanding of visual signal evolution. [ABSTRACT FROM AUTHOR]

Many chemically-defended/aposematic species rely on diet for sequestering the toxins with which they defend themselves. This dietary acquisition can lead to variable chemical defenses across space, as the community composition of chemical sources is likely to vary across the range of (an aposematic) species. We characterized the alkaloid content of two populations of the Dyeing Poison Frog (Dendrobates tinctorius) in northeastern French Guiana. Additionally, we conducted unpalatability experiments with naive predators, Blue Tits (Cyanistes caeruleus), using whole-skin secretion cocktails to assess how a model predator would respond to the defense of individuals from each population. While there was some overlap between the two D. tinctorius populations in terms of alkaloid content, our analysis revealed that these two populations are markedly distinct in terms of overall alkaloid profiles. Predator responses to skin secretions differed between the populations. We identified 15 candidate alkaloids (including three previously undescribed) in seven classes that are correlated with predator response in one frog population. We describe alkaloid profile differences between populations for D. tinctorius and provide a novel method for assessing unpalatability of skin secretions and identifying which toxins may contribute to the predator response. In one population, our results suggest 15 alkaloids that are implicated in predator aversive response. This method is the first step in identifying the causal link between alkaloids and behavioral responses of predators, and thus makes sense of how varying alkaloid combinations are capable of eliciting consistent behavioral responses, and eventually driving evolutionary change in aposematic characters (or characteristics). [ABSTRACT FROM AUTHOR]

Animal personality traits are sometimes linked to an individual's degree of plasticity, with certain personality types being more plastic than others. In territorial species, consistently high levels of aggression might increase the risk of harmful fights, while consistently low aggression might lead to the loss of a territory. Consequently, reacting plastically with an appropriate territorial response should be beneficial to avoid these risks. An integrative investigation of both personality traits and plasticity can help us better understand the dynamics of aggressive interactions during male-male competition. Here, we used a free-ranging Neotropical poison frog population to investigate the role of plasticity in male territorial aggression towards intruders. We conducted repeated standardized territorial intrusion experiments mimicking frogs of different body sizes via playback calls with different peak frequencies. We found individual repeatability for the latency to reach and approach a simulated intruder and observed that both aggressive and less aggressive males decreased their level of aggression towards big intruders. However, our results do not support a correlation between personality and plasticity in the context of male territory defense during the breeding season. We discuss how such a correlation between personality and plasticity might be conditional on the costs and benefits across contexts. [ABSTRACT FROM AUTHOR]

We used data from a five-year study at two focal breeding wetlands of a single Crawfish Frog (Rana areolata) population to demonstrate the relative importance and potential of tadpole survival as a target for population management. We concurrently estimated 11 vital rates in the field and used a females-only matrix projection model to estimate elasticities of demographic rates. We then simulated stochastic population dynamics at each wetland with and without immigration to estimate the intrinsic capacity for each focal breeding wetland to sustain a Crawfish Frog breeding population and the likelihood of breeding population persistence at each wetland. Elasticity of tadpole survival was second only to juvenile survival elasticity and 1.34-2.04 times greater than adult survival elasticity. Projections indicated that the Crawfish Frog population was not at risk of extinction but only one breeding site was capable of self-sustaining a breeding population. Because of low tadpole survival, the other breeding site was completely dependent on immigration to persist and was functioning as a population sink. Despite higher variability compared to terrestrial vital rates, larval survival did have a strong effect on population growth. Tadpole survival at the more productive breeding site was density dependent and likely related to wetland vegetation and predator and competitor abundance. Two additional findings were that annual survival of frogs following their first known breeding event was 48% lower compared to survival of frogs that had bred in two or more prior years, and adult temporary emigration from the breeding population was moderately high. Our study demonstrates the benefits of using population models that integrate density-dependent processes, temporary emigration from the breeding population, and state-specific adult survival, to identify larval habitats that function as population sinks and limit current population size and persistence probability. We contend that tadpole survival is an important and feasible habitat management target within broader conservation strategies for Crawfish Frogs and other amphibian species. [ABSTRACT FROM AUTHOR]

The correction notice in the journal "Conservation Genetics" addresses the article "Genetic assessment and monitoring of wild, captive, and reintroduced northern leopard frog populations" by Parinaz Khalilzadeh et al. The authors have opted for Open Choice, making the article an Open Access publication under the Creative Commons Attribution 4.0 International License. The correction ensures proper credit and distribution rights for the article, allowing for use, sharing, and reproduction with appropriate acknowledgment. [Extracted from the article]