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PeerJ 2022The recent emergence of the pathogen () is associated with rapid population declines of salamanders in Europe and its arrival to new areas could cause dramatic negative...
The recent emergence of the pathogen () is associated with rapid population declines of salamanders in Europe and its arrival to new areas could cause dramatic negative effects on other amphibian populations and species. Amphibian species, present in areas with high amphibian diversity such as Mexico, could be highly threatened due to the arrival of , particularly salamander species which are more vulnerable to chytridiomycosis caused by this pathogen. Thus, immediate surveillance is needed as a strategy to efficiently contend with this emerging infectious disease. In this study, we analyzed 490 wild and captive amphibians from 48 species across 76 sites in the North, Central, and South of Mexico to evaluate the presence of . Amphibians were sampled in sites with variable degrees of amphibian richness and suitability for according to previous studies. From the 76 sampling sites, 10 of them were located in areas with high amphibian richness and potential moderate to high habitat suitability. We did not detect in any of the samples, and no signs of the disease were observed in any individual at the time of sampling. Our results suggest that has not yet arrived at the sampled sites or could be at low prevalence within populations with low occurrence probability. This is the first study that evaluates the presence of in different regions and amphibian species in Mexico, which is the second most diverse country in salamander species in the world. We highlight the risk and the importance of continuing surveillance of in Mexico and discuss control strategies to avoid the introduction and spread of in the country.
Topics: Animals; Mexico; Chytridiomycota; Amphibians; Batrachochytrium; Urodela
PubMed: 36213512
DOI: 10.7717/peerj.14117 -
PloS One 2016Madagascar has become a model region for testing hypotheses of species diversification and biogeography, and many studies have focused on its diverse and highly endemic...
Madagascar has become a model region for testing hypotheses of species diversification and biogeography, and many studies have focused on its diverse and highly endemic herpetofauna. Here we combine species distribution models of a near-complete set of species of reptiles and amphibians known from the island with body size data and a tabulation of herpetofaunal communities from field surveys, compiled up to 2008. Though taxonomic revisions and novel distributional records arose since compilation, we are confident that the data are appropriate for inferring and comparing biogeographic patterns among these groups of organisms. We observed species richness of both amphibians and reptiles was highest in the humid rainforest biome of eastern Madagascar, but reptiles also show areas of high richness in the dry and subarid western biomes. In several amphibian subclades, especially within the Mantellidae, species richness peaks in the central eastern geographic regions while in reptiles different subclades differ distinctly in their richness centers. A high proportion of clades and subclades of both amphibians and reptiles have a peak of local endemism in the topographically and bioclimatically diverse northern geographic regions. This northern area is roughly delimited by a diagonal spanning from 15.5°S on the east coast to ca. 15.0°S on the west coast. Amphibian diversity is highest at altitudes between 800-1200 m above sea-level whereas reptiles have their highest richness at low elevations, probably reflecting the comparatively large number of species specialized to the extended low-elevation areas in the dry and subarid biomes. We found that the range sizes of both amphibians and reptiles strongly correlated with body size, and differences between the two groups are explained by the larger body sizes of reptiles. However, snakes have larger range sizes than lizards which cannot be readily explained by their larger body sizes alone. Range filling, i.e., the amount of suitable habitat occupied by a species, is less expressed in amphibians than in reptiles, possibly reflecting their lower dispersal capacity. Taxonomic composition of communities assessed by field surveys is largely explained by bioclimatic regions, with communities from the dry and especially subarid biomes distinctly differing from humid and subhumid biomes.
Topics: Amphibians; Animals; Biodiversity; Madagascar; Models, Biological; Phylogeny; Principal Component Analysis; Reptiles
PubMed: 26735688
DOI: 10.1371/journal.pone.0144076 -
Ecological Applications : a Publication... Mar 2023Invasive species and emerging infectious diseases are two of the greatest threats to biodiversity. American Bullfrogs (Rana [Lithobates] catesbeiana), which have been...
Invasive species and emerging infectious diseases are two of the greatest threats to biodiversity. American Bullfrogs (Rana [Lithobates] catesbeiana), which have been introduced to many parts of the world, are often linked with declines in native amphibians via predation and the spread of emerging pathogens such as amphibian chytrid fungus (Batrachochytrium dendrobatidis [Bd]) and ranaviruses. Although many studies have investigated the potential role of bullfrogs in the decline of native amphibians, analyses that account for shared habitat affinities and imperfect detection have found limited support for clear effects. Similarly, the role of bullfrogs in shaping the patch-level distribution of pathogens is unclear. We used eDNA methods to sample 233 sites in the southwestern USA and Sonora, Mexico (2016-2018) to estimate how the presence of bullfrogs affects the occurrence of four native amphibians, Bd, and ranaviruses. Based on two-species, dominant-subordinate occupancy models fitted in a Bayesian context, federally threatened Chiricahua Leopard Frogs (Rana chiricahuensis) and Western Tiger Salamanders (Ambystoma mavortium) were eight times (32% vs. 4%) and two times (36% vs. 18%), respectively, less likely to occur at sites where bullfrogs occurred. Evidence for the negative effects of bullfrogs on Lowland Leopard Frogs (Rana yavapaiensis) and Northern Leopard Frogs (Rana pipiens) was less clear, possibly because of smaller numbers of sites where these native species still occurred and because bullfrogs often occur at lower densities in streams, the primary habitat for Lowland Leopard Frogs. At the community level, Bd was most likely to occur where bullfrogs co-occurred with native amphibians, which could increase the risk to native species. Ranaviruses were estimated to occur at 33% of bullfrog-only sites, 10% of sites where bullfrogs and native amphibians co-occurred, and only 3% of sites where only native amphibians occurred. Of the 85 sites where we did not detect any of the five target amphibian species, we also did not detect Bd or ranaviruses; this suggests other hosts do not drive the distribution of these pathogens in our study area. Our results provide landscape-scale evidence that bullfrogs reduce the occurrence of native amphibians and increase the occurrence of pathogens, information that can clarify risks and aid the prioritization of conservation actions.
Topics: Animals; Rana catesbeiana; Bayes Theorem; Chytridiomycota; Amphibians; Ranidae; Biodiversity
PubMed: 36478292
DOI: 10.1002/eap.2785 -
Revue Scientifique Et Technique... Aug 2010Although they are frequently lumped together, reptiles and amphibians belong to two very different zoological groups. Nevertheless, one fact is clear: while numerous...
Although they are frequently lumped together, reptiles and amphibians belong to two very different zoological groups. Nevertheless, one fact is clear: while numerous reptile and amphibian species on Earth are in decline, others have taken advantage of trade or human movements to become established in new lands, adopting different, and sometimes unusual, strategies. The authors have taken a few examples from these two zoological groups that illustrate the majority of cases. A brief analysis of the causes and effects of their introductions into new areas reveals connections with economic interests, trade in companion animals, medical research and public health.
Topics: Amphibians; Animals; Anura; Bufo marinus; Colubridae; Humans; Iguanas; Introduced Species; Rana catesbeiana; Reptiles; Turtles; Xenopus laevis
PubMed: 20919579
DOI: No ID Found -
Hormones and Behavior Feb 2015This article is part of a Special Issue "Chemosignals and Reproduction". Amphibians are often thought of as relatively simple animals especially when compared to... (Review)
Review
This article is part of a Special Issue "Chemosignals and Reproduction". Amphibians are often thought of as relatively simple animals especially when compared to mammals. Yet the chemosignaling systems used by amphibians are varied and complex. Amphibian chemosignals are particularly important in reproduction, in both aquatic and terrestrial environments. Chemosignaling is most evident in salamanders and newts, but increasing evidence indicates that chemical communication facilitates reproduction in frogs and toads as well. Reproductive hormones shape the production, dissemination, detection, and responsiveness to chemosignals. A large variety of chemosignals have been identified, ranging from simple, invariant chemosignals to complex, variable blends of chemosignals. Although some chemosignals elicit straightforward responses, others have relatively subtle effects. Review of amphibian chemosignaling reveals a number of issues to be resolved, including: 1) the significance of the complex, individually variable blends of courtship chemosignals found in some salamanders, 2) the behavioral and/or physiological functions of chemosignals found in anuran "breeding glands", 3) the ligands for amphibian V2Rs, especially V2Rs expressed in the main olfactory epithelium, and 4) the mechanism whereby transdermal delivery of chemosignals influences behavior. To date, only a handful of the more than 7000 species of amphibians has been examined. Further study of amphibians should provide additional insight to the role of chemosignals in reproduction.
Topics: Amphibians; Animals; Hormones; Pheromones; Reproduction
PubMed: 24945995
DOI: 10.1016/j.yhbeh.2014.06.008 -
The Journal of Experimental ZoologyThe structure and function of the oviducts of members of the three Orders of the Class Amphibia (Anura, frogs and toads; Urodela, salamanders and newts; Gymnophiona,... (Review)
Review
The structure and function of the oviducts of members of the three Orders of the Class Amphibia (Anura, frogs and toads; Urodela, salamanders and newts; Gymnophiona, caecilians) are well described for only a few species. Further, the majority of such descriptions relate only to temperate species that breed in water, lay their eggs there, and have free-living larvae, the presumed ancestral condition of oviparity. Many species of amphibians have derived reproductive modes. Such modes include breeding terrestrially and arboreally, making foam nests, parental transport of eggs and/or tadpoles, direct development (copulating on land, laying the eggs in terrestrial sites, fully metamorphosed juveniles hatching, obviating the free-living larval stage). Other derived modes are ovoviviparity (developing embryos retained in the oviducts, born at a diversity stages of development, no maternal nutrition in addition to yolk) and viviparity (oviductal retention of developing young, maternal nutrition after yolk is resorbed, young born as fully metamorphosed juveniles). The amphibian oviduct is regionally differentiated to secrete varying numbers of layers of material around each egg, which function in fertilization, etc.; it is responsive to endocrine output and environmental mediation during the reproductive cycle; and it maintains developing embryos in some members of all three orders, some with oviductal epithelial secretion of nutrients. However, little is known of the structure-function relationships of the oviduct in species with derived reproductive modes. A comparison of oviduct morphology, function, endocrinology, ecology and phylogeny in amphibians with diverse reproductive modes suggests a number of highly productive avenues of investigation.
Topics: Amphibians; Animals; Female; Oviducts; Pregnancy; Reproduction
PubMed: 9803536
DOI: No ID Found -
Dong Wu Xue Yan Jiu = Zoological... Jul 2016Model organisms have long been important in biology and medicine due to their specific characteristics. Amphibians, especially Xenopus, play key roles in answering... (Review)
Review
Model organisms have long been important in biology and medicine due to their specific characteristics. Amphibians, especially Xenopus, play key roles in answering fundamental questions on developmental biology, regeneration, genetics, and toxicology due to their large and abundant eggs, as well as their versatile embryos, which can be readily manipulated and developed in vivo. Furthermore, amphibians have also proven to be of considerable benefit in human disease research due to their conserved cellular developmental and genomic organization. This review gives a brief introduction on the progress and limitations of these animal models in biology and human disease research, and discusses the potential and challenge of Microhyla fissipes as a new model organism.
Topics: Amphibians; Animals; Cell Cycle; Humans; Models, Animal; Regeneration; Research Design; Toxicology
PubMed: 27469255
DOI: 10.13918/j.issn.2095-8137.2016.4.237 -
Zootaxa Jul 2014Parasitological studies on helminths of amphibians in South America have increased in the past few years. Here, we present a list with summarized data published on...
Parasitological studies on helminths of amphibians in South America have increased in the past few years. Here, we present a list with summarized data published on helminths of South American amphibians from 1925 to 2012, including a list of helminth parasites, host species, and geographic records. We found 194 reports of helminths parasitizing 185 amphibian species from eleven countries: Argentina, Brazil, Chile, Colombia, Equador, French Guyana, Guyana, Paraguay, Peru, Uruguay and Venezuela. Helminth biodiversity includes 278 parasite species of the groups Acanthocephala, Nematoda, Cestoda, Monogenea and Trematoda. A list of helminth parasite species per host, and references are also presented. This contribution aims to document the biodiversity of helminth parasites in South American amphibians, as well as identify gaps in our knowledge, which in turn may guide subsequent studies.
Topics: Amphibians; Animals; Biodiversity; Checklist; Ecosystem; Female; Helminthiasis, Animal; Helminths; Host Specificity; Male; South America
PubMed: 25082165
DOI: 10.11646/zootaxa.3843.1.1 -
Journal of Morphology Aug 2015Live-bearing has evolved in all three orders of amphibians--frogs, salamanders, and caecilians. Developing young may be either yolk dependent, or maternal nutrients may...
Live-bearing has evolved in all three orders of amphibians--frogs, salamanders, and caecilians. Developing young may be either yolk dependent, or maternal nutrients may be supplied after yolk is resorbed, depending on the species. Among frogs, embryos in two distantly related lineages develop in the skin of the maternal parents' backs; they are born either as advanced larvae or fully metamorphosed froglets, depending on the species. In other frogs, and in salamanders and caecilians, viviparity is intraoviductal; one lineage of salamanders includes species that are yolk dependent and born either as larvae or metamorphs, or that practice cannibalism and are born as metamorphs. Live-bearing caecilians all, so far as is known, exhaust yolk before hatching and mothers provide nutrients during the rest of the relatively long gestation period. The developing young that have maternal nutrition have a number of heterochronic changes, such as precocious development of the feeding apparatus and the gut. Furthermore, several of the fetal adaptations, such as a specialized dentition and a prolonged metamorphosis, are homoplasious and present in members of two or all three of the amphibian orders. At the same time, we know little about the developmental and functional bases for fetal adaptations, and less about the factors that drive their evolution and facilitate their maintenance.
Topics: Adaptation, Physiological; Amphibians; Animals; Biological Evolution; Female; Viviparity, Nonmammalian
PubMed: 24643944
DOI: 10.1002/jmor.20271 -
Diseases of Aquatic Organisms Dec 2020Batrachochytrium salamandrivorans (Bsal), a pathogenic fungus causing the fatal disease chytridiomycosis in amphibians, was likely introduced to Europe through the trade...
Batrachochytrium salamandrivorans (Bsal), a pathogenic fungus causing the fatal disease chytridiomycosis in amphibians, was likely introduced to Europe through the trade in pet salamanders from Asia and then escaped into wild populations. Among European countries, Spain has a large number of private breeders and keepers of pet salamanders, and cases of Bsal in wild and captive populations already have been confirmed there. However, surveillance for the pathogen in Spanish collections of amphibians is sparse. Therefore, assisted by private owners and breeders, we surveyed 10 amphibian collections and analysed a total of 317 samples for presence of Bsal. All of our analyses yielded negative results. However, this apparent lack of Bsal cases in captivity should not encourage relaxation of vigilance, quarantine efforts or good practices. Because amphibian collections represent highly dynamic environments (animals are coming in and out), the pathogen could easily be introduced into a collection by new individuals. Any case of Bsal infection in captive animals could lead to its further spread to wild populations of susceptible species, potentially decimating them, and thus should be prevented.
Topics: Amphibians; Animals; Asia; Batrachochytrium; Chytridiomycota; Europe; Spain; Urodela
PubMed: 33269721
DOI: 10.3354/dao03535