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Current Opinion in Neurobiology Dec 2021Recent studies have served to emphasize the unique placement of amphibians, composed of more than 8000 species, in the evolution of the brain. We provide an overview of... (Review)
Review
Recent studies have served to emphasize the unique placement of amphibians, composed of more than 8000 species, in the evolution of the brain. We provide an overview of the three amphibian orders and their respective ecologies, behaviors, and brain anatomy. Studies have probed the origins of independently evolved parental care strategies in frogs and the biophysical principles driving species-specific differences in courtship vocalization patterns. Amphibians are also important models for studying the central control of movement, especially in the context of the vertebrate origin of limb-based locomotion. By highlighting the versatility of amphibians, we hope to see a further adoption of anurans, urodeles, and gymnophionans as model systems for the evolution and neural basis of behavior across vertebrates.
Topics: Amphibians; Animals; Biological Evolution; Brain; Locomotion; Neurobiology; Vertebrates
PubMed: 34481981
DOI: 10.1016/j.conb.2021.07.015 -
Conservation Biology : the Journal of... Feb 2021Amphibian populations globally are in decline. One great threat is the abstraction of water resources that alter surface-water hydrology. Conservation actions aimed at... (Review)
Review
Amphibian populations globally are in decline. One great threat is the abstraction of water resources that alter surface-water hydrology. Conservation actions aimed at restoring or manipulating surface water are employed as a management tool, but empirical evidence on the effectiveness of these approaches is scarce. In this systematic review, we summarized the global experience of manipulating water for amphibian conservation. We explored examples of manipulating water to conserve amphibian species and communities. Approaches varied in their frequency of implementation and in their success. Extending hydroperiod to match larval requirements showed encouraging results, as did off-season drying to control predators. Spraying water into the environment showed several potential applications, but successes were limited. Despite some promising interventions, we identified few (n = 17) empirically supported examples of successful water manipulation to benefit amphibians. It is unclear whether this stems from publication bias or if it is an artifact of language selection. However, manipulating water shows some potential in amphibian conservation, particularly at sites with a proximal water source and in regions where aridity is increasing due to climate change. Regardless of the scale of the intervention or its perceived probability of success, high-quality reporting of empirical results will further understanding of how water manipulations can benefit threatened amphibian populations.
Topics: Amphibians; Animals; Climate Change; Conservation of Natural Resources; Water
PubMed: 32189374
DOI: 10.1111/cobi.13501 -
FEMS Microbiology Reviews Jan 2023This review summarizes the role of environmental factors on amphibian microbiotas at the organismal, population, community, ecosystem, and biosphere levels. At the... (Review)
Review
This review summarizes the role of environmental factors on amphibian microbiotas at the organismal, population, community, ecosystem, and biosphere levels. At the organismal-level, tissue source, disease status, and experimental manipulations were the strongest predictors of variation in amphibian microbiotas. At the population-level, habitat quality, disease status, and ancestry were commonly documented as drivers of microbiota turnover. At the community-level, studies focused on how species' niche influence microbiota structure and function. At the ecosystem-level, abiotic and biotic reservoirs were important contributors to microbiota structure. At the biosphere-level, databases, sample banks, and seminatural experiments were commonly used to describe microbiota assembly mechanisms among temperate and tropical amphibians. Collectively, our review demonstrates that environmental factors can influence microbiotas through diverse mechanisms at all biological scales. Importantly, while environmental mechanisms occurring at each of the different scales can interact to shape microbiotas, the past 10 years of research have mostly been characterized by targeted approaches at individual scales. Looking forward, efforts considering how environmental factors at multiple organizational levels interact to shape microbiota diversity and function are paramount. Generating opportunities for meaningful cross-disciplinary interactions and supporting infrastructure for research that spans biological scales are imperative to addressing this gap.
Topics: Animals; Ecosystem; Microbiota; Amphibians; Phylogeny
PubMed: 36725211
DOI: 10.1093/femsre/fuad002 -
Integrated Environmental Assessment and... Jan 2023Chemical exposure estimation through the dermal route is an underemphasized area of ecological risk assessment for terrestrial animals. Currently, there are efforts to...
Chemical exposure estimation through the dermal route is an underemphasized area of ecological risk assessment for terrestrial animals. Currently, there are efforts to create exposure models to estimate doses from this pathway for use in ecological risk assessment. One significant limitation has been insufficient published data to characterize exposure and to support the selection and parameterization of appropriate models, particularly for amphibians in terrestrial habitats. Recent publications measuring pesticide doses to terrestrial-phase amphibians have begun to rectify this situation. We collated and summarized available measurements of terrestrial amphibian dermal exposure to pesticides from 11 studies in which researchers measured tissue concentrations associated with known pesticide experimental application rates. This data set included tissue concentrations in 11 amphibian species and 14 different pesticides. We then compared the results of two screening exposure models that differed based on surface area scaling approaches as a function of body weight (one based on birds as surrogates for amphibians and another amphibian-specific) to the measured tissue residue concentrations. We define a false-negative rate for each screening model as the proportion of amphibians for which the predicted concentration is less than the observed concentration (i.e., underestimate), contrary to the intent of screening models, which are intended to have a bias for higher exposure concentrations. The screening model that uses birds as surrogates did not have any instances where estimated expected avian doses were less than measured amphibian body burdens. When using the amphibian-specific exposure model that corrected for differences between avian and amphibian surface area, measured concentrations were greater than model estimates for 11.3% of the 1158 comparisons. The database of measured pesticide concentrations in terrestrial amphibians is provided for use in calculating bioconcentration factors and for future amphibian dermal exposure model development. Integr Environ Assess Manag 2023;19:9-16. © 2022 SETAC. This article has been contributed to by U.S. Government employees and their work is in the public domain in the USA.
Topics: Animals; Amphibians; Pesticides; Ecosystem; Soil
PubMed: 35412009
DOI: 10.1002/ieam.4619 -
Scientific Reports Sep 2020Two species of parasitic fungi from the phylum Chytridiomycota (chytrids) are annihilating global amphibian populations. These chytrid species-Batrachochytrium...
Two species of parasitic fungi from the phylum Chytridiomycota (chytrids) are annihilating global amphibian populations. These chytrid species-Batrachochytrium dendrobatidis and B. salamandrivorans-have high rates of mortality and transmission. Upon establishing infection in amphibians, chytrids rapidly multiply within the skin and disrupt their hosts' vital homeostasis mechanisms. Current disease models suggest that chytrid fungi locate and infect their hosts during a motile, unicellular 'zoospore' life stage. Moreover, other chytrid species parasitize organisms from across the tree of life, making future epidemics in new hosts a likely possibility. Efforts to mitigate the damage and spread of chytrid disease have been stymied by the lack of knowledge about basic chytrid biology and tools with which to test molecular hypotheses about disease mechanisms. To overcome this bottleneck, we have developed high-efficiency delivery of molecular payloads into chytrid zoospores using electroporation. Our electroporation protocols result in payload delivery to between 75 and 97% of living cells of three species: B. dendrobatidis, B. salamandrivorans, and a non-pathogenic relative, Spizellomyces punctatus. This method lays the foundation for molecular genetic tools needed to establish ecological mitigation strategies and answer broader questions in evolutionary and cell biology.
Topics: Amphibians; Animal Diseases; Animals; Chytridiomycota; Electroporation; Host-Pathogen Interactions; Mycoses; Spores, Fungal
PubMed: 32934254
DOI: 10.1038/s41598-020-71618-2 -
Comparative Biochemistry and... Mar 2021The globin gene repertoire of gnathostome vertebrates is dictated by differential retention and loss of nine paralogous genes: androglobin, neuroglobin, globin X,...
The globin gene repertoire of gnathostome vertebrates is dictated by differential retention and loss of nine paralogous genes: androglobin, neuroglobin, globin X, cytoglobin, globin Y, myoglobin, globin E, and the α- and β-globins. We report the globin gene repertoire of three orders of modern amphibians: Anura, Caudata, and Gymnophiona. Combining phylogenetic and conserved synteny analysis, we show that myoglobin and globin E were lost only in the Batrachia clade, but retained in Gymnophiona. The major amphibian groups also retained different paralogous copies of globin X. None of the amphibian presented α-globin gene. Nevertheless, two clades of β-globins are present in all amphibians, indicating that the amphibian ancestor possessed two paralogous proto β-globins. We also show that orthologs of the gene coding for the monomeric hemoglobin found in the heart of Rana catesbeiana are present in Neobatrachia and Pelobatoidea species we analyzed. We suggest that these genes might perform myoglobin- and globin E-related functions. We conclude that the repertoire of globin genes in amphibians is dictated by both retention and loss of the paralogous genes cited above and the rise of a new globin gene through co-option of an α-globin, possibly facilitated by a prior event of transposition.
Topics: Amphibians; Animals; Evolution, Molecular; Globins; Phylogeny; Synteny
PubMed: 33202310
DOI: 10.1016/j.cbd.2020.100759 -
Philosophical Transactions of the Royal... Jul 2023As a class of vertebrates, amphibians, are at greater risk for declines or extinctions than any other vertebrate group, including birds and mammals. There are many... (Review)
Review
As a class of vertebrates, amphibians, are at greater risk for declines or extinctions than any other vertebrate group, including birds and mammals. There are many threats, including habitat destruction, invasive species, overuse by humans, toxic chemicals and emerging diseases. Climate change which brings unpredictable temperature changes and rainfall constitutes an additional threat. Survival of amphibians depends on immune defences functioning well under these combined threats. Here, we review the current state of knowledge of how amphibians respond to some natural stressors, including heat and desiccation stress, and the limited studies of the immune defences under these stressful conditions. In general, the current studies suggest that desiccation and heat stress can activate the hypothalamus pituitary-interrenal axis, with possible suppression of some innate and lymphocyte-mediated responses. Elevated temperatures can alter microbial communities in amphibian skin and gut, resulting in possible dysbiosis that fosters reduced resistance to pathogens. This article is part of the theme issue 'Amphibian immunity: stress, disease and ecoimmunology'.
Topics: Animals; Amphibians; Climate Change; Heat-Shock Response; Introduced Species; Knowledge; Mammals
PubMed: 37305907
DOI: 10.1098/rstb.2022.0132 -
Zootaxa Jun 2023North Sweden ('Norrland' in Swedish) covers 243 000 km2 and lies mainly in the boreal biome. The herpetofauna comprises five amphibian and four reptile species:...
North Sweden ('Norrland' in Swedish) covers 243 000 km2 and lies mainly in the boreal biome. The herpetofauna comprises five amphibian and four reptile species: Lissotriton vulgaris, Triturus cristatus, Bufo bufo, Rana temporaria, Rana arvalis, Zootoca vivipara, Anguis fragilis, Natrix natrix, and Vipera berus. Successful conservation and management of amphibians and reptiles depend on accurate information about distribution, habitat affinities, and abundance. Such knowledge is also essential as a benchmark to assess changes in distribution and abundance that may come about as a result of climate change and human habitat alteration. This paper aims to present accurate distribution maps, describe habitat affinities, and provide abundance estimates for the herpetofauna of North Sweden for the period 1970-2022. Distribution data are presented by traditional faunistic provinces, as well as by biotic regions and alpine life zones. Separate sections address post-glacial colonization and a herpetological perspective on anthropogenic changes in relation to species´ present status. Bufo bufo, Rana temporaria, Rana arvalis, Zootoca vivipara, and Vipera berus are widely distributed throughout the boreal sub-regions. Rana temporaria, Zootoca vivipara, and Vipera berus also extend into the alpine region. Triturus cristatus, Anguis fragilis, and Natrix natrix occur mainly in the coastal parts of the Southern Boreal region. There are no signs of recent changes in distribution range, but Lissotriton vulgaris, Triturus cristatus, and Rana arvalis have been largely overlooked in the past and have a much wider occurrence than previously recognized. Most species are found in habitats usually not described in all-European field guides. Nearly all anurans hibernate in water. Abundance estimates suggest that some species are more common in the boreal than thought, supporting the notion that a large share of their total European population occurs there. Although local extinctions and declines are known, there are no signs of widespread population decline for any species during the study period.
Topics: Humans; Animals; Sweden; Amphibians; Reptiles; Ecosystem; Anura; Ranidae; Viperidae; Colubridae; Lizards
PubMed: 37518558
DOI: 10.11646/zootaxa.5301.3.1 -
Biotechnology and Bioengineering Feb 2024In recent years, environmental DNA (eDNA) has received attention from biologists due to its sensitivity, convenience, labor and material efficiency, and lack of damage... (Review)
Review
In recent years, environmental DNA (eDNA) has received attention from biologists due to its sensitivity, convenience, labor and material efficiency, and lack of damage to organisms. The extensive application of eDNA has opened avenues for the monitoring and biodiversity assessment of amphibians, which are frequently small and difficult to observe in the field, in areas such as biodiversity survey assessment and detection of specific, rare and threatened, or alien invasive species. However, the accuracy of eDNA can be influenced by factors such as ambient temperature, pH, and false positives or false negatives, which makes eDNA an adjunctive tool rather than a replacement for traditional surveys. This review provides a concise overview of the eDNA method and its workflow, summarizes the differences between applying eDNA for detecting amphibians and other organisms, reviews the research progress in eDNA technology for amphibian monitoring, identifies factors influencing detection efficiency, and discusses the challenges and prospects of eDNA. It aims to serve as a reference for future research on the application of eDNA in amphibian detection.
Topics: Animals; DNA, Environmental; Ecosystem; Amphibians; Biodiversity
PubMed: 37986625
DOI: 10.1002/bit.28592 -
Toxins Oct 2022The skin of amphibians is a tissue with biological functions, such as defense, respiration, and excretion. In recent years, researchers have discovered a large number of... (Review)
Review
The skin of amphibians is a tissue with biological functions, such as defense, respiration, and excretion. In recent years, researchers have discovered a large number of peptides in the skin secretions of amphibians, including antimicrobial peptides, antioxidant peptides, bradykinins, insulin-releasing peptides, and other peptides. This review focuses on the origin, primary structure, secondary structure, length, and functions of peptides secreted from amphibians' skin. We hope that this review will provide further information and promote the further study of amphibian skin secretions, in order to provide reference for expanding the research and application of amphibian bioactive peptides.
Topics: Animals; Antimicrobial Peptides; Antioxidants; Amino Acid Sequence; Amphibians; Peptides; Skin; Insulins; Amphibian Proteins
PubMed: 36287990
DOI: 10.3390/toxins14100722