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The International Journal of... 2021The axial skeleton of the has undergone an evolutionary reduction of its bone elements. This structural plan is strongly preserved throughout the order and would have... (Review)
Review
The axial skeleton of the has undergone an evolutionary reduction of its bone elements. This structural plan is strongly preserved throughout the order and would have emerged as a highly specialized anatomical adaptation to its locomotor jumping pattern. The development programs that direct the vertebral morphogenesis of the anurans are poorly described and the molecular bases that have caused their pattern to differ from other tetrapods are completely unknown. In this work, we review the ontogeny of the spinal column of the anurans and explore the genetic mechanisms that could explain the morphological difference and the maintenance of the body plan during evolution. Here, we propose that the absence of caudal osseous elements, as a consequence of the inability of sclerotomes to form cartilaginous condensations in frogs, could be due to changes in both pattern and expression levels of , , and genes along the anteroposterior axis. The anteriorised expression of the genes together with the reduction in the expression levels of , and in the posterior somites could explain, at least partly, the loss of caudal vertebrae in the anurans during evolution.
Topics: Animals; Anura; Bone and Bones; Gene Expression Regulation, Developmental; Genes, Homeobox; Skeleton; Somites
PubMed: 32930370
DOI: 10.1387/ijdb.200230ss -
Current Biology : CB Jan 2019Hybridogenesis is an unusual form of reproduction that is found in hybrids between different species. It involves the selective transmission of one of the parental...
Hybridogenesis is an unusual form of reproduction that is found in hybrids between different species. It involves the selective transmission of one of the parental genomes, while the other one is renewed by mating with the corresponding species. It is seen as a form of sexual parasitism, in which the hybridogenetic genome gains a twofold transmission advantage and exploits the reproductive effort of another species.
Topics: Animals; Anura; Biological Evolution; Fishes; Genome; Hybridization, Genetic; Insecta; Reproduction
PubMed: 30620918
DOI: 10.1016/j.cub.2018.11.046 -
Comparative Biochemistry and... Mar 2021August Krogh's studies of the frog identified the respiratory function of the skin in 1904 and the osmoregulatory function of the skin in 1937. It is the thesis of my... (Review)
Review
August Krogh's studies of the frog identified the respiratory function of the skin in 1904 and the osmoregulatory function of the skin in 1937. It is the thesis of my review that the osmoregulatory function of the skin has evolved for meeting quite different demands. In freshwater the body fluid homeostasis is challenged by loss of ions to the environment. This is compensated for by active ion uptake energized by the sodium-pump ATPase and the V-type proton pump ATPase. I conclude that Krogh's astonishing observation of cutaneous chloride uptake from μM concentrations of NaCl is compatible with the free energy changes of ATP hydrolysis catalyzed by the sodium‑potassium pump ATPase and the V-type proton pump ATPase operating in series, and in parallel with experimentally verified vanishingly small leak fluxes. On land the frog is challenged by evaporative water loss through the highly water permeable skin, similar to the water permeable conducting airways of terrestrial vertebrates including man. The epithelia serving respiratory gas exchanges are heterocellular and have molecular, structural and functional properties in common. The cutaneous surface liquid of amphibians evolved for protecting the skin epithelium from desiccation like the airway surface liquid of the lung. Published studies of ion transport mechanisms of acinar cells and the two types of epithelial cells, lead to the hypothesis that subepithelial gland secretion, evaporative water loss, and ion reabsorption by the epithelium regulate composition and volume of the cutaneous surface liquid.
Topics: Animals; Anura; Epithelial Cells; Epithelium; Ion Transport; Osmoregulation; Skin Physiological Phenomena; Sodium-Potassium-Exchanging ATPase; Vacuolar Proton-Translocating ATPases; Water-Electrolyte Balance
PubMed: 33326845
DOI: 10.1016/j.cbpa.2020.110869 -
Current Biology : CB Nov 2015Stynoski et al. introduce the dendrobatids, a charismatic group of frogs known for their colourful and often poisonous skin.
Stynoski et al. introduce the dendrobatids, a charismatic group of frogs known for their colourful and often poisonous skin.
Topics: Animals; Anura; Female; Male; Poisons; Skin; Skin Pigmentation; Toxins, Biological
PubMed: 26528739
DOI: 10.1016/j.cub.2015.06.044 -
Current Biology : CB Sep 2020David and Karin Pfennig introduce character displacement, the divergent evolution of traits in overlapping species.
David and Karin Pfennig introduce character displacement, the divergent evolution of traits in overlapping species.
Topics: Animals; Anura; Biological Evolution; Phenotype; Selection, Genetic; Species Specificity
PubMed: 32961151
DOI: 10.1016/j.cub.2020.07.021 -
Genetics and Molecular Research : GMR Aug 2014This article reviews the polyploidy events that have long been demonstrated to play a role in the evolution of Anura, while also discussing the importance of epigenetic... (Review)
Review
This article reviews the polyploidy events that have long been demonstrated to play a role in the evolution of Anura, while also discussing the importance of epigenetic control of gene expression and diversity. Findings on Brazilian autopolyploid anurans, mainly of the genus Odontophrynus, obtained in previous studies on their cytogenetics, chromatin ultrastructure, and molecular gene regulation are discussed here. Our data on genome duplication and on epigenetic events were analyzed here regarding phylogenetic trees, including the classic 2R model for vertebrate evolution and the growing evidence of similar epigenetic mechanisms in animal and allopolyploid plants. We propose that polyploidy and epigenetic events led to rapid Anura diversity and speciation. Also, recent advances in molecular studies in other organisms led us to revisit some controversial models of evolution.
Topics: Amphibians; Animals; Anura; Brazil; Chromosomes, Plant; Epigenesis, Genetic; Epigenomics; Evolution, Molecular; Gene Expression Regulation, Plant; Hybridization, Genetic; Phylogeny; Phylogeography; Polymorphism, Genetic; Polyploidy
PubMed: 25117358
DOI: 10.4238/2014.August.7.15 -
Microbiome Mar 2022The fungal pathogen Batrachochytrium dendrobatidis (Bd) threatens amphibian biodiversity and ecosystem stability worldwide. Amphibian skin microbial community structure...
BACKGROUND
The fungal pathogen Batrachochytrium dendrobatidis (Bd) threatens amphibian biodiversity and ecosystem stability worldwide. Amphibian skin microbial community structure has been linked to the clinical outcome of Bd infections, yet its overall functional importance is poorly understood.
METHODS
Microbiome taxonomic and functional profiles were assessed using high-throughput bacterial 16S rRNA and fungal ITS2 gene sequencing, bacterial shotgun metagenomics and skin mucosal metabolomics. We sampled 56 wild midwife toads (Alytes obstetricans) from montane populations exhibiting Bd epizootic or enzootic disease dynamics. In addition, to assess whether disease-specific microbiome profiles were linked to microbe-mediated protection or Bd-induced perturbation, we performed a laboratory Bd challenge experiment whereby 40 young adult A. obstetricans were exposed to Bd or a control sham infection. We measured temporal changes in the microbiome as well as functional profiles of Bd-exposed and control animals at peak infection.
RESULTS
Microbiome community structure and function differed in wild populations based on infection history and in experimental control versus Bd-exposed animals. Bd exposure in the laboratory resulted in dynamic changes in microbiome community structure and functional differences, with infection clearance in all but one infected animal. Sphingobacterium, Stenotrophomonas and an unclassified Commamonadaceae were associated with wild epizootic dynamics and also had reduced abundance in laboratory Bd-exposed animals that cleared infection, indicating a negative association with Bd resistance. This was further supported by microbe-metabolite integration which identified functionally relevant taxa driving disease outcome, of which Sphingobacterium and Bd were most influential in wild epizootic dynamics. The strong correlation between microbial taxonomic community composition and skin metabolome in the laboratory and field is inconsistent with microbial functional redundancy, indicating that differences in microbial taxonomy drive functional variation. Shotgun metagenomic analyses support these findings, with similar disease-associated patterns in beta diversity. Analysis of differentially abundant bacterial genes and pathways indicated that bacterial environmental sensing and Bd resource competition are likely to be important in driving infection outcomes.
CONCLUSIONS
Bd infection drives altered microbiome taxonomic and functional profiles across laboratory and field environments. Our application of multi-omics analyses in experimental and field settings robustly predicts Bd disease dynamics and identifies novel candidate biomarkers of infection. Video Abstract.
Topics: Animals; Anura; Chytridiomycota; Microbiota; Mycoses; RNA, Ribosomal, 16S
PubMed: 35272699
DOI: 10.1186/s40168-021-01215-6 -
Genes Mar 2021Frogs are ideal organisms for studying sex chromosome evolution because of their diversity in sex chromosome differentiation and sex-determination systems. We review 222... (Review)
Review
Frogs are ideal organisms for studying sex chromosome evolution because of their diversity in sex chromosome differentiation and sex-determination systems. We review 222 anuran frogs, spanning ~220 Myr of divergence, with characterized sex chromosomes, and discuss their evolution, phylogenetic distribution and transitions between homomorphic and heteromorphic states, as well as between sex-determination systems. Most (~75%) anurans have homomorphic sex chromosomes, with XY systems being three times more common than ZW systems. Most remaining anurans (~25%) have heteromorphic sex chromosomes, with XY and ZW systems almost equally represented. There are Y-autosome fusions in 11 species, and no W-/Z-/X-autosome fusions are known. The phylogeny represents at least 19 transitions between sex-determination systems and at least 16 cases of independent evolution of heteromorphic sex chromosomes from homomorphy, the likely ancestral state. Five lineages mostly have heteromorphic sex chromosomes, which might have evolved due to demographic and sexual selection attributes of those lineages. Males do not recombine over most of their genome, regardless of which is the heterogametic sex. Nevertheless, telomere-restricted recombination between ZW chromosomes has evolved at least once. More comparative genomic studies are needed to understand the evolutionary trajectories of sex chromosomes among frog lineages, especially in the ZW systems.
Topics: Animals; Anura; Evolution, Molecular; Female; Male; Phylogeny; Sex Chromosomes; Sex Determination Processes
PubMed: 33810524
DOI: 10.3390/genes12040483 -
Brain, Behavior and Evolution 2022The underlying hypothesis that motivates research into the relationship between ecology, cognition, and the hippocampus is that selection to solve problems in nature... (Review)
Review
The underlying hypothesis that motivates research into the relationship between ecology, cognition, and the hippocampus is that selection to solve problems in nature shapes cognition through changes in the hippocampus. This hypothesis has been explored almost exclusively in mammals and birds. However, if one is interested in the principles that shape the evolution of vertebrate cognition, work in amphibians is essential. To address this gap, we have developed a research program contrasting cognitive abilities and hippocampal neurobiology in two species of frog with distinct social and spatial ecologies. We have found that the poison frog Dendrobates auratus, a diurnal species whose interactions with the physical and social environment are complex, is more adept and flexible at spatial learning and learned inhibition than the túngara frog, a nocturnal species that lacks complex interactions with the spatial and social environment. Because spatial learning and learned inhibition are closely associated with hippocampal function in other vertebrates, we used RNA sequencing to characterize molecular differences in the hippocampus of the two species. We have found that D. auratus has greater levels of expression of genes associated with neurogenesis, synaptic plasticity, and cellular activity, and lower levels of expression of genes associated with apoptosis, compared to the túngara frog. Our studies are consistent with the idea that D. auratus, with their more complex social and spatial ecology, have enhanced hippocampally dependent cognitive abilities compared to túngara frogs. Further characterization of the features of hippocampal neurobiology that confer distinctive cognitive abilities will help elucidate the neural features that are necessary for the evolution of enhanced hippocampally dependent cognition.
Topics: Animals; Anura; Cognition; Hippocampus; Learning; Mammals; Neuronal Plasticity
PubMed: 35051940
DOI: 10.1159/000522108 -
Scientific Reports Oct 2023Exploring the timing of life-history transitions has been a pivotal focus in the field of evolutionary ecology. Studies on amphibian metamorphosis are well suited to...
Exploring the timing of life-history transitions has been a pivotal focus in the field of evolutionary ecology. Studies on amphibian metamorphosis are well suited to investigate this aspect. We propose a species-specific model to predict the optimal metamorphosis point for frog individuals with different larval growth trajectories. Because overall fitness will be determined throughout both aquatic and terrestrial stages, we included growth and survival rates of aquatic and terrestrial stages in the fitness equation. Then we conducted a rearing experiment on a brown frog, Rana ornativentris, as an example to obtain the size at metamorphosis, larval period, and larval growth trajectory. Based on these results, we determined the model's parameters to fit the actual metamorphosis patterns. Because the parameters are supposed to be evolutionarily maintained, our data-driven approach enabled obtaining fundamental ecological information (evolutionally-based life-history parameters) of the target species. Comparing the parameters among species will allow us to understand the mechanisms in determining life-history transition more deeply.
Topics: Humans; Animals; Metamorphosis, Biological; Anura; Larva; Ranidae; Morphogenesis
PubMed: 37783741
DOI: 10.1038/s41598-023-43639-0