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Molecular Phylogenetics and Evolution Jun 2024Unusually for oceanic islands, the granitic Seychelles host multiple lineages of endemic amphibians. This includes an ancient (likely ca. 60 million years) radiation of...
Unusually for oceanic islands, the granitic Seychelles host multiple lineages of endemic amphibians. This includes an ancient (likely ca. 60 million years) radiation of eight caecilian species, most of which occur on multiple islands.These caecilians have a complicated taxonomic history and their phylogenetic inter-species relationships have been difficult to resolve. Double-digest RAD sequencing (ddRADseq) has been applied extensively to phylogeography and increasingly to phylogenetics but its utility for resolving ancient divergences is less well established. To address this, we applied ddRADseq to generate a genome-wide SNP panel for phylogenomic analyses of the Seychelles caecilians, whose phylogeny has so far not been satisfactorily resolved with traditional DNA markers. Based on 129,154 SNPs, we resolved deep and shallow splits, with strong support. Our findings demonstrate the capability of genome-wide SNPs for evolutionary inference at multiple taxonomic levels and support the recently proposed synonymy of Grandisonia Taylor, 1968 with Hypogeophis Peters, 1879. We revealed three clades of Hypogeophis (large-, medium- and short-bodied) and identify a single origin of the diminutive, stocky-bodied and pointy-snouted phenotype.
PubMed: 38889862
DOI: 10.1016/j.ympev.2024.108130 -
Proceedings. Biological Sciences Jun 2024Biological invasions are among the threats to global biodiversity and social sustainability, especially on islands. Identifying the threshold of area at which non-native...
Biological invasions are among the threats to global biodiversity and social sustainability, especially on islands. Identifying the threshold of area at which non-native species begin to increase abruptly is crucial for early prevention strategies. The small-island effect (SIE) was proposed to quantify the nonlinear relationship between native species richness and area but has not yet been applied to non-native species and thus to predict the key breakpoints at which established non-native species start to increase rapidly. Based on an extensive global dataset, including 769 species of non-native birds, mammals, amphibians and reptiles established on 4277 islands across 54 archipelagos, we detected a high prevalence of SIEs across 66.7% of archipelagos. Approximately 50% of islands have reached the threshold area and thus may be undergoing a rapid increase in biological invasions. SIEs were more likely to occur in those archipelagos with more non-native species introduction events, more established historical non-native species, lower habitat diversity and larger archipelago area range. Our findings may have important implications not only for targeted surveillance of biological invasions on global islands but also for predicting the responses of both non-native and native species to ongoing habitat fragmentation under sustained land-use modification and climate change.
Topics: Introduced Species; Islands; Animals; Biodiversity; Conservation of Natural Resources; Ecosystem; Birds; Amphibians; Mammals; Reptiles
PubMed: 38889781
DOI: 10.1098/rspb.2024.0844 -
Comparative Biochemistry and... Jun 2024Ivermectin (IVM) is a broad-spectrum veterinary antiparasitic used worldwide in cattle breeding. The aim of this study was to evaluate the lethal effects of the active...
Ivermectin (IVM) is a broad-spectrum veterinary antiparasitic used worldwide in cattle breeding. The aim of this study was to evaluate the lethal effects of the active ingredient and a commercial formulation of IVM (1 % active ingredient) in the embryonic stage (S. 4-6) and larval stage (S. 25) of the South American amphibian Rhinella arenarum through chronic standardized bioassays. Also, behavior analysis and oxidative stress and cholinergic effects biomarkers were analyzed at 1, 10 and 100 μg IVM/L concentrations. For the embryonic stage, the active ingredient (96 h- LC: 15900 μg/L) was more toxic than the commercial formulation (96 h-LC: 51230 μg/L) during the acute period, while at chronic exposure the commercial formulation was more toxic (504 h-LC: 10.25 μg/L), compared to the active ingredient (504 h-LC: 312.80 μg/L). For the larval stage, in acute exposure, the active ingredient (96 h-LC: 800 μg/L) was more toxic than the commercial formulation (96 h-LC: 1550 μg/L). In the chronic exposure, the commercial formulation (504 h-LC: 77.33 μg/L) was more toxic than the active ingredient (504 h-LC: 195.25 μg/L). Overall, larvae exhibited greater sensitivity to both the active ingredient and the commercial formulation. However, during chronic exposure, embryos were more sensitive to the commercial formulation than larvae. The commercial formulation primarily induced oxidative stress, and both forms of the compound affected behavior and cholinergic effect biomarkers, even at low environmentally relevant concentrations (1 μg/L). These results highlight the potential impact of IVM on aquatic ecosystems.
PubMed: 38885750
DOI: 10.1016/j.cbpc.2024.109965 -
Proceedings of the National Academy of... Jun 2024An often-overlooked question of the biodiversity crisis is how natural hazards contribute to species extinction risk. To address this issue, we explored how four natural...
An often-overlooked question of the biodiversity crisis is how natural hazards contribute to species extinction risk. To address this issue, we explored how four natural hazards, earthquakes, hurricanes, tsunamis, and volcanoes, overlapped with the distribution ranges of amphibians, birds, mammals, and reptiles that have either narrow distributions or populations with few mature individuals. To assess which species are at risk from these natural hazards, we combined the frequency and magnitude of each natural hazard to estimate their impact. We considered species at risk if they overlapped with regions where any of the four natural hazards historically occurred (n = 3,722). Those species with at least a quarter of their range subjected to a high relative impact were considered at high risk (n = 2,001) of extinction due to natural hazards. In total, 834 reptiles, 617 amphibians, 302 birds, and 248 mammals were at high risk and they were mainly distributed on islands and in the tropics. Hurricanes (n = 983) and earthquakes (n = 868) affected most species, while tsunamis (n = 272), and volcanoes (n = 171) affected considerably fewer. The region with the highest number of species at high risk was the Pacific Ring of Fire, especially due to volcanoes, earthquakes, and tsunamis, while hurricane-related high-risk species were concentrated in the Caribbean Sea, Gulf of Mexico, and northwestern Pacific Ocean. Our study provides important information regarding the species at risk due to natural hazards and can help guide conservation attention and efforts to safeguard their survival.
Topics: Extinction, Biological; Animals; Biodiversity; Birds; Mammals; Reptiles; Earthquakes; Cyclonic Storms; Tsunamis; Amphibians; Volcanic Eruptions; Natural Disasters
PubMed: 38885390
DOI: 10.1073/pnas.2321068121 -
Parasitology Research Jun 2024Acanthocephalans, in their adult stage, are obligatory parasites of many types of vertebrates, including anuran amphibians. Their complex life cycle always involves an...
Acanthocephalans, in their adult stage, are obligatory parasites of many types of vertebrates, including anuran amphibians. Their complex life cycle always involves an arthropod intermediate host but may include non-obligatory strategies that could improve transmission success, such as paratenic infections. In paratenic hosts, these parasites are normally found loose in the body cavity or encysted in internal organs. Here, we present the first report of acanthocephalans found encysted under the skin of an amphibian (i.e., external to its body cavity). The specimen, a clay robber frog [Haddadus binotatus (Spix, 1824)], had been collected in an Atlantic Forest area in southeastern Brazil. Upon examination of the frog, we recovered two specimens of acanthocephalan (Order Echinorhynchida) encysted under the skin of its venter. Considering the host's relatively small size and its thin ventral musculature, we believe that the acanthocephalans may have accidentally trespassed the muscular tissue while attempting to encyst in the frog's internal body wall.
Topics: Animals; Acanthocephala; Brazil; Anura; Helminthiasis, Animal; Skin
PubMed: 38884663
DOI: 10.1007/s00436-024-08270-6 -
PeerJ 2024The Montseny brook newt (), a glacial relict endemic to a small, isolated massif in northeast Spain, is considered the only Critically Endangered urodele in Europe. Its...
The Montseny brook newt (), a glacial relict endemic to a small, isolated massif in northeast Spain, is considered the only Critically Endangered urodele in Europe. Its restricted range is divided by a deep valley that acts as an impassable barrier to dispersal, separating two isolated metapopulations (Western and Eastern) that correspond to independent lineages with different evolutionary trajectories, based on genetic and genomic data. Here, we address the ecological differentiation between lineages and discuss its potential effect on the phenotypic distinctness of each lineage. Based on multiple lines of evidence, we formally describe the Western Montseny brook newt as a new subspecies: Finally, our study underscores the importance of considering taxonomic progress in the conservation policies of endangered species, ensuring appropriate management and protection of the newly described taxa.
Topics: Spain; Animals; Salamandridae; Endangered Species; Phylogeny
PubMed: 38881865
DOI: 10.7717/peerj.17550 -
Cellular and Molecular Life Sciences :... Jun 2024Acid-sensing ion channels (ASICs) are trimeric proton-gated cation channels that play a role in neurotransmission and pain sensation. The snake venom-derived peptides,...
Acid-sensing ion channels (ASICs) are trimeric proton-gated cation channels that play a role in neurotransmission and pain sensation. The snake venom-derived peptides, mambalgins, exhibit potent analgesic effects in rodents by inhibiting central ASIC1a and peripheral ASIC1b. Despite their distinct species- and subtype-dependent pharmacology, previous structure-function studies have focussed on the mambalgin interaction with ASIC1a. Currently, the specific channel residues responsible for this pharmacological profile, and the mambalgin pharmacophore at ASIC1b remain unknown. Here we identify non-conserved residues at the ASIC1 subunit interface that drive differences in the mambalgin pharmacology from rat ASIC1a to ASIC1b, some of which likely do not make peptide binding interactions. Additionally, an amino acid variation below the core binding site explains potency differences between rat and human ASIC1. Two regions within the palm domain, which contribute to subtype-dependent effects for mambalgins, play key roles in ASIC gating, consistent with subtype-specific differences in the peptides mechanism. Lastly, there is a shared primary mambalgin pharmacophore for ASIC1a and ASIC1b activity, with certain peripheral peptide residues showing variant-specific significance for potency. Through our broad mutagenesis studies across various species and subtype variants, we gain a more comprehensive understanding of the pharmacophore and the intricate molecular interactions that underlie ligand specificity. These insights pave the way for the development of more potent and targeted peptide analogues required to advance our understating of human ASIC1 function and its role in disease.
Topics: Acid Sensing Ion Channels; Animals; Humans; Rats; Elapid Venoms; Amino Acid Sequence; Binding Sites; Models, Molecular; Xenopus laevis; Peptides
PubMed: 38880807
DOI: 10.1007/s00018-024-05276-2 -
Veterinary Parasitology, Regional... Jul 2024Clinostomum spp. are common parasites of piscivorous birds. Metacercaria are typically observed in the muscles or just under the skin of fish and rarely amphibians. We...
Clinostomum spp. are common parasites of piscivorous birds. Metacercaria are typically observed in the muscles or just under the skin of fish and rarely amphibians. We describe an unusually severe case of Clinostomum marginatum infection in an adult female green tree frog (Hyla cinerea) from Georgia (USA). The frog was found in November 2015 with a high number (>250) of widely disseminated, raised, subcutaneous nodules. The frog died in December. At necropsy, it was emaciated, and the skin was covered in raised uniform, tan-green, subcutaneous, ∼2-3 mm diameter nodules. Each nodule contained 1-3 C. marginatum metacercariae. Microscopically, high numbers of trematodes were within subcutaneous tissues and in coelomic and oral cavities, lung, liver, kidney, ovary, orbit and calvarium. Small to large numbers of lymphocytes and melanomacrophages were in connective tissues and epidermis. A 732 bp region of COI was 98.8-99.8% similar to numerous sequences of C. marginatum and, phylogenetically it grouped with these C. marginatum sequences. The ITS-1 region was 100% similar to a C. marginatum sample from a great egret (Ardea alba) from Mississippi. This report represents a novel finding of severe trematodiasis in a free-ranging amphibian with C. marginatum infection.
Topics: Animals; Trematode Infections; Female; Anura; Trematoda; Georgia; Fatal Outcome; Larva
PubMed: 38880568
DOI: 10.1016/j.vprsr.2024.101051 -
Journal of Thermal Biology Jun 2024Thermal tolerance data are important for identifying the potential range of non-native species following introduction and establishment. Such data are particularly...
Thermal tolerance data are important for identifying the potential range of non-native species following introduction and establishment. Such data are particularly important for understanding invasion risks of tropical species introduced to temperate climates and identifying whether they can survive outside tropical regions. A breeding population of the tropical clawed frog (Xenopus tropicalis) was recently discovered in west-central Florida, U.S.A. This fully aquatic species is native to the rainforest belt of west Africa and has not been documented outside its native range. Because of the lack of invasion history, data are sparse on the thermal limits for this species. We used chronic lethal and critical thermal methodologies to investigate thermal tolerance on adult stages and critical thermal methods on tadpoles. Because of our use of both chronic and critical methodologies, we also examined the literature to reveal common methods used to investigate thermal minimum and maximum temperature in amphibians, which were found to be dominated by the critical maximum. Chronic lethal temperatures for adult X. tropicalis were 9.73 °C and 36.68 °C. Critical temperatures were affected by acclimation temperature and life stage; adults were more tolerant of extreme temperatures. Based on these critical thermal data and the fact that breeding tends to occur when temperatures are suitable for survival, tadpole stages are unlikely to be affected by extreme temperatures. Instead, range expansion in Florida will likely be limited by the adult stages. Our findings indicate that the tropical clawed frog could occupy much of southern Peninsular Florida and other tropical and subtropical regions worldwide.
PubMed: 38879911
DOI: 10.1016/j.jtherbio.2024.103890 -
Analytica Chimica Acta Aug 2024Harmful algal blooms (HABs), caused by the rapid proliferation or aggregation of microorganisms, are catastrophic for the environment. The Prymnesium parvum is a...
BACKGROUND
Harmful algal blooms (HABs), caused by the rapid proliferation or aggregation of microorganisms, are catastrophic for the environment. The Prymnesium parvum is a haptophyte algal species that is found worldwide and is responsible for extensive blooms and death of larval amphibians and bivalves, causing serious negative impacts on the ecological environment. For the prevention and management of environmental pollution, it is crucial to explore and develop early detection strategies for HABs on-site using simple methods. The major challenge related to early detection is the accurate and sensitive detection of algae present in low abundance.
RESULTS
Herein, recombinase polymerase amplification (RPA) was combined with clustered regularly interspaced short palindromic repeats and Cas12a protein (CRISPR-LbaCas12a) systems, and the lateral flow dipstick (LFD) was used for the first time for early detection of P. parvum. The internal transcribed spacer (ITS) of P. parvum was selected as the target sequence, and the concentration of single-strand DNA reporters, buffer liquid system, reaction time, and amount of gold particles were optimized. The RPA-CRISPR-LbaCas12a-LFD approach demonstrated highly specificity during experimental testing, with no cross-reaction against different microalgae used as controls. In addition, the lowest detection limit was 10,000 times better than the lowest detection limit of the standalone RPA approach. The feasibility and robustness of this approach were further verified by using the different environmental samples. It also observed that P. parvum are widely distributed in Chinese Sea, but the cell density of P. parvum is relatively low (<0.1 cells/mL).
SIGNIFICANCE
The developed approach has an excellent specificity and offers 10,000 times better sensitivity than the standalone RPA approach. These advantages make this approach suitable for early warning detection and prevention of HAB events in environmental water. Also, the outcomes of this study could promote a shift from traditional laboratory-based detection to on-site monitoring, facilitating early warning against HABs.
Topics: CRISPR-Cas Systems; Limit of Detection; Nucleic Acid Amplification Techniques; Recombinases; Harmful Algal Bloom; Gold; CRISPR-Associated Proteins; Endodeoxyribonucleases; Bacterial Proteins
PubMed: 38879209
DOI: 10.1016/j.aca.2024.342797