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The Science of the Total Environment Oct 2019Nanomaterials (NMs) have been used in a growing number of commercial products, and their rapid expansion could lead to their release into the aquatic environments.... (Review)
Review
Nanomaterials (NMs) have been used in a growing number of commercial products, and their rapid expansion could lead to their release into the aquatic environments. However, there is limited knowledge about the impact of NMs in the biota, especially the amphibians. The present study revised the historical use of amphibian species as a model system for nanoecotoxicological studies and summarized the data available in the scientific literature about the genotoxic, mutagenic, histopathological, embryotoxic and reproductive effects of NMs in different groups of amphibians. The interaction, bioaccumulation, mode of action (MoA) and ecotoxicity of NMs on amphibians were also revised. The nanoecotoxicological studies were conducted with 11 amphibian species, being eight species of the order Anura and three species of the order Caudata. Xenopus laevis was the most studied species. The studies were conducted mainly with inorganic NMs (72%) compared to organic ones. The nanoecotoxicity depends on NM behavior and transformation in the environment, as well as the developmental stages of amphibians. The known effects of NMs in amphibians were mainly reported with reactive oxygen species (ROS) production, oxidative stress, and genotoxic effects. Results emphasize the need for further studies testing the ecotoxicity of different NMs, concentrations and exposure periods at environmentally relevant approaches. Furthermore, standard protocols for nanoecotoxicological tests using amphibians are required. Revised data showed that amphibians are suitable organisms to assess the environmental impact of NMs and indicated significant research gaps concerning the ecotoxicity of NMs on freshwater ecosystems and recommendations for future researches.
Topics: Amphibians; Animals; Biota; Mutagens; Nanostructures; Oxidative Stress; Water Pollutants, Chemical
PubMed: 31181520
DOI: 10.1016/j.scitotenv.2019.05.487 -
Journal of Experimental Zoology. Part... Apr 2022Quantifying ectotherm body temperature is important to understand physiological performance under environmental change. The increasing availability of small,...
Quantifying ectotherm body temperature is important to understand physiological performance under environmental change. The increasing availability of small, commercially-available animal-borne biologgers increases accessibility to high-quality body temperature data. However, amphibians present several challenges to successful datalogger implantation including small body sizes and physiologically active skin. We developed a method for the implantation, extraction, and validation of temperature biologgers in captive salamanders. We assessed the effect of biologger implantation and extraction surgery on body condition. Implantation had no effects on short or long-term body condition. Body condition also did not differ between implant and control groups after datalogger extraction. Biologgers did not alter preferred temperature in a laboratory thermal gradient, indicating that temperature data would not be biased by implantation. We provide detailed recommendations for datalogger placement and refinement of surgical techniques to further improve outcomes, enhance our understanding of fitness, species range limitations, and responses to environmental and climatic change.
Topics: Amphibians; Animals; Body Temperature; Climate Change; Temperature; Urodela
PubMed: 34982510
DOI: 10.1002/jez.2575 -
Philosophical Transactions of the Royal... Aug 2023Amphibians exhibit an incredible diversity of reproductive and life-history strategies, including various forms of nest construction and nesting behaviour. Although... (Review)
Review
Amphibians exhibit an incredible diversity of reproductive and life-history strategies, including various forms of nest construction and nesting behaviour. Although anuran amphibians (frogs and toads) are not known for their nests, nesting behaviour in this clade-broadly defined as a location chosen or constructed for eggs and young-is tightly linked to the amphibious lifestyle of this group. Transitions to increasingly terrestrial living have driven reproductive diversity in anurans, including the repeated, independent evolution of nests and nesting. Indeed, a core feature of many notable anuran adaptations-including nesting behaviour-is the maintenance of an aquatic environment for developing offspring. The tight link between increasingly terrestrial reproduction and morphological, physiological and behavioural diversity in anurans provides inroads for studying the evolutionary ecology of nests, their architects and their contents. This review provides an overview of nests and nesting behaviour in anurans, highlighting areas where additional work may be particularly fruitful. I take an intentionally broad view of what constitutes nesting to highlight what we can learn from thinking and researching comparatively across anurans and vertebrates more broadly. This article is part of the theme issue 'The evolutionary ecology of nests: a cross-taxon approach'.
Topics: Anura; Biological Evolution; Ecosystem; Life Cycle Stages; Nesting Behavior; Reproduction; Male; Female; Animals
PubMed: 37427468
DOI: 10.1098/rstb.2022.0141 -
Acta Parasitologica Mar 2023The diversity of larval digenetic trematodes can provide information on one or more intermediate hosts prior to maturation into the definitive host; on host activity and...
PURPOSE
The diversity of larval digenetic trematodes can provide information on one or more intermediate hosts prior to maturation into the definitive host; on host activity and distribution; and in some cases, on environmental perturbations. In this context, the goal of the present study was to analyse the trematode larvae found in adult amphibians collected from the Argentinian Chaco Region. Few studies have been reported on the systematics of larval digeneans in amphibians.
METHODS
A total of 167 specimens of frogs (Leptodactylus macrosternum, Leptodactylus latinasus, Lepidobatrachus laevis, Lepidobatrachus llanensis and Lysapsus limellum) and toads (Rhinella bergi) were examined for larval digeneans. Frogs and toads were collected in two Argentinian ecoregions (Dry Chaco and Humid Chaco); between June 2002 and December 2019. Morphology of each taxon was studied in detail using light microscopy and scanning electron microscopy (SEM).
RESULTS
Fourteen different taxa of the families Diplostomidae (Alariinae gen sp., Didelphodiplostomum sp., Pharingostomoides sp. and Tylodelphys sp.), Proterodiplostomidae (Heterodiplostomum lanceolatum), and Strigeidae (Strigea spp.) were found infecting the body cavity, mesentery, muscle, fluid in the spinal cord canal, and cranial cavity of amphibians. All species are described and illustrated, and their life cycles are briefly discussed.
CONCLUSION
These infections provide new information on the morphology, morphometry, and composition of the diversity of mesocercariae and metacercariae in amphibians, thus contributing to the knowledge of potential intermediate hosts. In addition, our results serve as an indicator of parasite and host biodiversity in different ecoregions of the Gran Chaco.
Topics: Humans; Animals; Trematode Infections; Trematoda; Larva; Anura; Biodiversity; Bufonidae
PubMed: 36542296
DOI: 10.1007/s11686-022-00650-1 -
Molecular Phylogenetics and Evolution Feb 2022The ability to bear live offspring, viviparity, has evolved multiple times across the tree of life and is a remarkable adaptation with profound life-history and...
The ability to bear live offspring, viviparity, has evolved multiple times across the tree of life and is a remarkable adaptation with profound life-history and ecological implications. Within amphibians the ancestral reproductive mode is oviparity followed by a larval life stage, but viviparity has evolved independently in all three amphibian orders. Two types of viviparous reproduction can be distinguished in amphibians; larviparity and pueriparity. Larviparous amphibians deliver larvae into nearby ponds and streams, while pueriparous amphibians deliver fully developed juveniles and thus do not require waterbodies for reproduction. Among amphibians, the salamander genus Salamandra is remarkable as it exhibits both inter- and intraspecific variation in the occurrence of larviparity and pueriparity. While the evolutionary relationships among Salamandra lineages have been the focus of several recent studies, our understanding of how often and when transitions between modes occurred is still incomplete. Furthermore, in species with intraspecific variation, the reproductive mode of a given population can only be confirmed by direct observation of births and thus the prevalence of pueriparous populations is also incompletely documented. We used sequence capture to obtain 1,326 loci from 94 individuals from across the geographic range of the genus, focusing on potential reproductive mode transition zones. We also report additional direct observations of pueriparous births for 20 new locations and multiple lineages. We identify at least five independent transitions from the ancestral mode of larviparity to pueriparity among and within species, occurring at different evolutionary timescales ranging from the Pliocene to the Holocene. Four of these transitions occurred within species. Based on a distinct set of markers and analyses, we also confirm previous findings of introgression between species and the need for taxonomic revisions in the genus. We discuss the implications of our findings with respect to the evolution of this complex trait, and the potential of using five independent convergent transitions for further studies on the ecological context in which pueriparity evolves and the genetic architecture of this specialized reproductive mode.
Topics: Animals; Biological Evolution; Humans; Oviparity; Phylogeny; Salamandra; Urodela; Viviparity, Nonmammalian
PubMed: 34763070
DOI: 10.1016/j.ympev.2021.107347 -
Annual Review of Microbiology Oct 2021Ancient enzootic associations between wildlife and their infections allow evolution to innovate mechanisms of pathogenicity that are counterbalanced by host responses.... (Review)
Review
Ancient enzootic associations between wildlife and their infections allow evolution to innovate mechanisms of pathogenicity that are counterbalanced by host responses. However, erosion of barriers to pathogen dispersal by globalization leads to the infection of hosts that have not evolved effective resistance and the emergence of highly virulent infections. Global amphibian declines driven by the rise of chytrid fungi and chytridiomycosis are emblematic of emerging infections. Here, we review how modern biological methods have been used to understand the adaptations and counteradaptations that these fungi and their amphibian hosts have evolved. We explore the interplay of biotic and abiotic factors that modify the virulence of these infections and dissect the complexity of this disease system. We highlight progress that has led to insights into how we might in the future lessen the impact of these emerging infections.
Topics: Amphibians; Animals; Chytridiomycota; Mycoses; Virulence
PubMed: 34351790
DOI: 10.1146/annurev-micro-052621-124212 -
Theriogenology Oct 2022The establishment and management of ex situ breeding and assurance populations around the globe are meant to provide short-term solutions to the formidable loss of... (Review)
Review
The establishment and management of ex situ breeding and assurance populations around the globe are meant to provide short-term solutions to the formidable loss of amphibian diversity presently occurring. Large multi-scaled facilities, such as zoos and aquariums, can provide the infrastructure to safeguard species and populations. However, often even large, economically viable facilities lack the knowledge to efficiently cater to the plethora of environmentally controlled physiological strategies that amphibians possess. Anurans present a class of amphibians that have often been viewed as easy to maintain ex situ. However, while adult survival may be relatively successful it is rarely accompanied by good reproductive output, health, and fitness. Even more conspicuous is the low survivorship of offspring produced ex situ once they are translocated back into the wild. The mountain yellow-legged frog (R. muscosa) ex situ breeding program EBP is a prime example of the challenges that amphibians EBPs face. Although more research is needed, the R. muscosa program has increased reproductive output and health of its colony by incorporating reproductive technologies and strategic genetic management in conjunction with a greater understanding of the species' natural history, to produce and translocate viable animals each year. This paper highlights the EBPs past decade of research featuring the program's contribution to building empirical, multidisciplinary approaches that boost the robustness of an endangered species, by safeguarding existing genetic diversity and maximizing fitness and survival outcomes.
Topics: Animals; Anura; Conservation of Natural Resources; Endangered Species; Reproduction; Reproductive Techniques
PubMed: 35986940
DOI: 10.1016/j.theriogenology.2022.07.003 -
Reproduction, Fertility, and Development Mar 2022Amphibians and reptiles are highly threatened vertebrate taxa with large numbers of species threatened with extinction. With so many species at risk, conservation... (Review)
Review
Amphibians and reptiles are highly threatened vertebrate taxa with large numbers of species threatened with extinction. With so many species at risk, conservation requires the efficient and cost-effective application of all the tools available so that as many species as possible are assisted. Biobanking of genetic material in genetic resource banks (GRBs) in combination with assisted reproductive technologies (ARTs) to retrieve live animals from stored materials are two powerful, complementary tools in the conservation toolbox for arresting and reversing biodiversity decline for both amphibians and reptiles. However, the degree of development of the ARTs and cryopreservation technologies differ markedly between these two groups. These differences are explained in part by different perceptions of the taxa, but also to differing reproductive anatomy and biology between the amphibians and reptiles. Artificial fertilisation with cryopreserved sperm is becoming a more widely developed and utilised technology for amphibians. However, in contrast, artificial insemination with production of live progeny has been reported in few reptiles, and while sperm have been successfully cryopreserved, there are still no reports of the production of live offspring generated from cryopreserved sperm. In both amphibians and reptiles, a focus on sperm cryopreservation and artificial fertilisation or artificial insemination has been at the expense of the development and application of more advanced technologies such as cryopreservation of the female germline and embryonic genome, or the use of sophisticated stem cell/primordial germ cell cryopreservation and transplantation approaches. This review accompanies the publication of ten papers on amphibians and twelve papers on reptiles reporting advances in ARTs and biobanking for the herpetological taxa.
Topics: Amphibians; Animals; Biological Specimen Banks; Goals; Reproductive Techniques, Assisted; Reptiles
PubMed: 35275052
DOI: 10.1071/RDv34n5_FO -
Experimental Cell Research Jul 2020Size is a fundamental feature of biology that affects physiology at all levels, from the organism to organs and tissues to cells and subcellular structures. How size is... (Review)
Review
Size is a fundamental feature of biology that affects physiology at all levels, from the organism to organs and tissues to cells and subcellular structures. How size is determined at these different levels, and how biological structures scale to fit together and function properly are important open questions. Historically, amphibian systems have been extremely valuable to describe scaling phenomena, as they occupy some of the extremes in biological size and are amenable to manipulations that alter genome and cell size. More recently, the application of biochemical, biophysical, and embryological techniques to amphibians has provided insight into the molecular mechanisms underlying scaling of subcellular structures to cell size, as well as how perturbation of normal size scaling impacts other aspects of cell and organism physiology.
Topics: Amphibians; Animals; Body Patterning; Body Size; Cell Size; Developmental Biology; Genome; Models, Biological; Organ Size
PubMed: 32343955
DOI: 10.1016/j.yexcr.2020.112036 -
Global Change Biology May 2024Amphibians and fishes play a central role in shaping the structure and function of freshwater environments. These organisms have a limited capacity to disperse across...
Amphibians and fishes play a central role in shaping the structure and function of freshwater environments. These organisms have a limited capacity to disperse across different habitats and the thermal buffer offered by freshwater systems is small. Understanding determinants and patterns of their physiological sensitivity across life history is, therefore, imperative to predicting the impacts of climate change in freshwater systems. Based on a systematic literature review including 345 experiments with 998 estimates on 96 amphibian (Anura/Caudata) and 93 freshwater fish species (Teleostei), we conducted a quantitative synthesis to explore phylogenetic, ontogenetic, and biogeographic (thermal adaptation) patterns in upper thermal tolerance (CT) and thermal acclimation capacity (acclimation response ratio, ARR) as well as the influence of the methodology used to assess these thermal traits using a conditional inference tree analysis. We found globally consistent patterns in CT and ARR, with phylogeny (taxa/order), experimental methodology, climatic origin, and life stage as significant determinants of thermal traits. The analysis demonstrated that CT does not primarily depend on the climatic origin but on experimental acclimation temperature and duration, and life stage. Higher acclimation temperatures and longer acclimation times led to higher CT values, whereby Anuran larvae revealed a higher CT than older life stages. The ARR of freshwater fishes was more than twice that of amphibians. Differences in ARR between life stages were not significant. In addition to phylogenetic differences, we found that ARR also depended on acclimation duration, ramping rate, and adaptation to local temperature variability. However, the amount of data on early life stages is too small, methodologically inconsistent, and phylogenetically unbalanced to identify potential life cycle bottlenecks in thermal traits. We, therefore, propose methods to improve the robustness and comparability of CT/ARR data across species and life stages, which is crucial for the conservation of freshwater biodiversity under climate change.
Topics: Animals; Acclimatization; Fishes; Fresh Water; Amphibians; Global Warming; Phylogeny; Climate Change; Temperature
PubMed: 38771091
DOI: 10.1111/gcb.17318