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Johnson PT, Calhoun DM, Achatz TJ, Greiman SE, Gestos A, Keeley WH. Outbreak of parasite-induced limb malformations in a declining amphibian species in Colorado. Int J Parasitol Parasites Wildl 2024; 24:100965. [PMID: 39132512 PMCID: PMC11315061 DOI: 10.1016/j.ijppaw.2024.100965] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/22/2024] [Revised: 07/11/2024] [Accepted: 07/11/2024] [Indexed: 08/13/2024]
Abstract
The detection of severe limb malformations in metamorphosing northern leopard frogs (Rana pipiens) from a Colorado pond in August 2022 prompted questions about the cause(s) and concern over the implications. Northern leopard frogs, which are a Tier 1 Species of Greatest Conservation Need in Colorado, have declined over much of their range in the state, particularly along the Front Range. Although malformations in amphibians have been reported in other parts of the USA, they are rare in Colorado, and the current case represents the most severe hotspot reported in the state for over 70 years. Across three survey events in late summer and early fall of 2022, approximately 68% of captured leopard frogs (late-stage larvae and metamorphic frogs) exhibited one or more malformations. Malformations exclusively affected the hind limbs and were dominated by skin webbings (51.7% of the total), bony triangles (32.2%), and extra limbs or digits (11%). Many animals had multiple malformations that limited the movement of one or both limbs (average of 2.3 malformations per malformed frog). Dissection of a subset of animals coupled with 28S rDNA genetic sequencing revealed the occurrence of the trematode Ribeiroia ondatrae at an average of 75.2 trematode cysts (metacercariae) per frog. The parasite was also detected in 2.6% of dissected snails (Helisoma trivolvis), which function as the trematode's first intermediate host. The relatively high loads of infection detected here - coupled with the similarity of observed malformations to those previously linked to R. ondatrae in experimental studies and from other malformation hotspots in the USA - offer compelling evidence that the current case is the result of parasite infection. Unresolved questions include why malformation prevalence was so high in 2022 and the degree to which such abnormalities will affect population persistence for local leopard frogs, particularly if malformations continue.
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Affiliation(s)
| | - Dana M. Calhoun
- Ecology and Evolutionary Biology, University of Colorado, Boulder, CO, USA
| | - Tyler J. Achatz
- Department of Natural Sciences, Middle Georgia State University, Macon, GA, 31206, USA
| | - Stephen E. Greiman
- Department of Biology, Georgia Southern University, Statesboro, GA, 30460, USA
| | - Adrian Gestos
- Mechanical Engineering, University of Colorado, Boulder, CO, USA
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2
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Svinin AO, Chikhlyaev IV, Bashinskiy IW, Osipov VV, Neymark LA, Ivanov AY, Stoyko TG, Chernigova PI, Ibrogimova PK, Litvinchuk SN, Ermakov OA. Diversity of trematodes from the amphibian anomaly P hotspot: Role of planorbid snails. PLoS One 2023; 18:e0281740. [PMID: 36989233 PMCID: PMC10057761 DOI: 10.1371/journal.pone.0281740] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/28/2022] [Accepted: 01/30/2023] [Indexed: 03/30/2023] Open
Abstract
Trematode infection of the second intermediate hosts can lead to changes in their fitness and, as a result, a change in the invasion rate of animal communities. It is especially pronounced during the invasion of parasite species that reduce activity due to the manipulation of hosts through the changes of their morphology and physiology. One of these cases is an anomaly P syndrome hotspot found in some populations of water frogs and toads in Europe caused by the trematode Strigea robusta metacercariae. The occurrence of pathogen and their participation in ecosystems are intrigues questions in the anomaly P phenomenon, as well as the role of planorbid snails that serve as the first intermediate hosts for many trematode species. Herein, we focused on trematodes spectra from planorbid snails and amphibians from the anomaly P hosts with the aim to undetected interactions between the pathways of parasites. Emerging cercariae of 6802 planorbid snails of dominant species (Planorbarius corneus, Planorbis planorbis, and Anisus spp.) were detected by both morphological and molecular methods in seven waterbodies in Privolzhskaya Lesostep Nature Reserve (Russia). A total of 95 sequences of 18 species were received, and 48 sequences were unique and did not present in any genetic databases. The 18 species of trematodes from snails and 14 species of trematodes from amphibian hosts (Pelophylax ridibundus; Ranidae; Anura) were detected. Three species (Echinostoma nasincovae, Tylodelphys circibuteonis and Australapatemon burti) was new for the trematode fauna of the Middle Volga River region and Russia as a whole. Eleven species of parasitic flatworms have amphibians in their life cycles and nine species used amphibians as metacercariae hosts: Echinostoma nasincovae, E. miyagawai, Echinoparyphium recurvatum, Tylodelphys circibuteonis, Neodiplostomum spathula, Paralepoderma cloacicola, Macrodera longicollis, Strigea robusta, and Strigea strigis. The occurrence of trematode species from planorbid mollusks and frogs were compared.
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Affiliation(s)
- Anton O Svinin
- Institute of Environmental and Agricultural Biology (X-BIO), Tyumen State University, Tyumen, Russia
| | - Igor V Chikhlyaev
- Institute of Ecology of Volga River Basin, Samara Federal Research Scientific Center RAS, Togliatti, Russia
| | - Ivan W Bashinskiy
- Laboratory of Ecology of Aquatic Communities and Invasions, A.N. Severtsov Institute of Ecology and Evolution, Russian Academy of Sciences, Moscow, Russia
| | - Vitaly V Osipov
- Privolzhskaya Lesosteppe State Nature Reserve, Penza, Russia
| | - Leonid A Neymark
- Institute of Ecology of Volga River Basin, Samara Federal Research Scientific Center RAS, Togliatti, Russia
| | | | - Tamara G Stoyko
- Department of Zoology and Ecology, Penza State University, Penza, Russia
| | - Polina I Chernigova
- Institute of Environmental and Agricultural Biology (X-BIO), Tyumen State University, Tyumen, Russia
| | - Polina K Ibrogimova
- Institute of Environmental and Agricultural Biology (X-BIO), Tyumen State University, Tyumen, Russia
| | | | - Oleg A Ermakov
- Department of Zoology and Ecology, Penza State University, Penza, Russia
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3
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Torrent L, Apoznański G, Kokurewicz T, Mitrus C, De Maegdt M, Juste J. First record of polydactyly for a European bat, Myotis daubentonii (Chiroptera, Vespertilionidae). MAMMALIA 2022. [DOI: 10.1515/mammalia-2022-0015] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
Abstract
Despite being one of the most common congenital hand abnormalities in humans, polydactyly remains extremely rare in bats. To date, it has been observed only in two insectivorous families in North America (Molossidae and Vespertilionidae) and a single case for the New World fruit bats (Phyllostomidae). We report the first case of polydactyly in a European bat – a Myotis daubentonii (Vespertilionidae), with eight toes. The bat was found alive, hibernating in the Natura 2000 site (PLH080003 “Nietoperek”) in Poland.
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Affiliation(s)
- Laura Torrent
- Natural Sciences Museum of Granollers , Francesc Macià 51 , Granollers , 08401 , Spain
- CIBIO-InBIO, Research Centre in Biodiversity and Genetic Resources , University of Porto , Campus de Vairão, 4485-661 , Vairão , Portugal
| | - Grzegorz Apoznański
- Department of Vertebrate Ecology and Paleontology , Institute of Environmental Biology, Wrocław University of Environmental and Life Sciences , Chełmońskiego 38c , 51-631 Wrocław , Poland
| | - Tomasz Kokurewicz
- Department of Vertebrate Ecology and Paleontology , Institute of Environmental Biology, Wrocław University of Environmental and Life Sciences , Chełmońskiego 38c , 51-631 Wrocław , Poland
| | - Cezary Mitrus
- Department of Vertebrate Ecology and Paleontology , Institute of Environmental Biology, Wrocław University of Environmental and Life Sciences , Chełmońskiego 38c , 51-631 Wrocław , Poland
| | - Maya De Maegdt
- Biodiversity, Conservation and Restoration , University of Antwerp , Campus Drie Eiken, Universiteitsplein 1 , 2610 Antwerpen , Belgium
| | - Javier Juste
- Estación Biológica de Doñana, C.S.I.C. , Avda. Américo Vespucio 26 , 41092 Sevilla , Spain
- CIBER de Epidemiología y Salud Pública, CIBERESP , 28220 , Madrid , Spain
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4
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Acute mortality in California tiger salamander (Ambystoma californiense) and Santa Cruz long-toed salamander (Ambystoma macrodactylum croceum) caused by Ribeiroia ondatrae (Class: Trematoda). Int J Parasitol Parasites Wildl 2021; 16:255-261. [PMID: 36120602 PMCID: PMC9475429 DOI: 10.1016/j.ijppaw.2021.10.008] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/17/2021] [Revised: 10/12/2021] [Accepted: 10/12/2021] [Indexed: 11/20/2022]
Abstract
In early September 2019, a morbidity and mortality event affecting California tiger salamanders (Ambystoma californiense) and Santa Cruz long-toed salamanders (Ambystoma macrodactylum croceum) in late stages of metamorphosis was reported at a National Wildlife Refuge in Santa Cruz County, California, U.S.A. During the postmortem disease investigation, severe integumentary metacercarial (Class: Trematoda) infection, associated with widespread skin lesions, was observed. Planorbid snails collected from the ponds of the refuge within seven days of the mortality event were infected with Ribeiroia ondatrae, a digenetic trematode that can cause malformation and death in some amphibians. We suggest sustained seasonal high-water levels due to active habitat management along with several years of increased rainfall led to increased bird visitation, increased over-wintering of snails, and prolonged salamander metamorphosis, resulting in a confluence of conditions and cascading of host-parasite dynamics to create a hyper-parasitized state. Mortality event in wild endangered salamanders in California. Infection with Ribeiroia ondatrae caused severe fatal skin lesions. Sustaining water levels may increase parasite transmission.
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Donald DB. Water quality limitations for tadpoles of the Wood Frog in the northern Great Plains, Canada. ENVIRONMENTAL MONITORING AND ASSESSMENT 2021; 193:636. [PMID: 34498140 DOI: 10.1007/s10661-021-09385-4] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/25/2021] [Accepted: 08/10/2021] [Indexed: 06/13/2023]
Abstract
Some wetlands in the northern Great Plains support hundreds to thousands of late-stage tadpoles providing important sources of recruitment to the Wood Frog (Lithobates sylvaticus) population while many other wetlands produce none. Relationships between water quality and late-stage tadpole abundance were determined to identify the water quality parameters associated with tadpole abundance. Water samples were collected, and late-stage tadpole abundances were assessed once each year in late June for 12 years in 26 wetlands. Catch or abundance was the number of tadpoles captured in 30 min with a dip-net. The catch of tadpoles was variable both among wetlands and over the long-term for individual wetlands, and ranged from 0 to several hundred individuals. Wood Frog tadpoles were especially sensitive to sodium and chloride concentrations. At Cl concentrations less than 5 mg/L, occupancy for late-stage tadpoles was 84%, and declined by about 8% for each 5 mg/L increase in Cl to 40.1 mg/L Cl, the maximum concentration associated with the detection of tadpoles. Optimal water quality for late-stage Wood Frog tadpoles included low concentrations of Na [Formula: see text] = 8.1 mg/L), and Cl [Formula: see text] = 4.2 mg/L) relative to total dissolved solids and other ions, and high concentrations of phosphorus. In a landscape where ion concentrations in wetlands can range over 3 orders of magnitude, water quality analyses suggest that abundant Wood Frog tadpole populations occur in wetlands dominated by snow-melt runoff with its characteristic low ion concentrations. The present study highlights the importance to amphibian conservation of the water quality environment of tadpole habitat.
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Affiliation(s)
- David B Donald
- Environment and Climate Change Canada, Alvin Hamilton Building, 1783 Hamilton Street, Regina, SK, S4P 2B4, Canada.
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6
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Wale N, Duffy MA. The Use and Underuse of Model Systems in Infectious Disease Ecology and Evolutionary Biology. Am Nat 2021; 198:69-92. [PMID: 34143716 DOI: 10.1086/714595] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/04/2022]
Abstract
AbstractEver since biologists began studying the ecology and evolution of infectious diseases (EEID), laboratory-based model systems have been important for developing and testing theory. Yet what EEID researchers mean by the term "model systems" and what they want from them is unclear. This uncertainty hinders our ability to maximally exploit these systems, identify knowledge gaps, and establish effective new model systems. Here, we borrow a definition of model systems from the biomolecular sciences to assess how EEID researchers are (and are not) using 10 key model systems. According to this definition, model systems in EEID are not being used to their fullest and, in fact, cannot even be considered model systems. Research using these systems consistently addresses only two of the three fundamental processes that underlie disease dynamics-transmission and disease, but not recovery. Furthermore, studies tend to focus on only a few scales of biological organization that matter for disease ecology and evolution. Moreover, the field lacks an infrastructure to perform comparative analyses. We aim to begin a discussion of what we want from model systems, which would further progress toward a thorough, holistic understanding of EEID.
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Svinin AO, Bashinskiy IV, Litvinchuk SN, Ermakov OA, Ivanov AY, Neymark LA, Vedernikov AA, Osipov VV, Drobot GP, Dubois A. Strigea robusta causes polydactyly and severe forms of Rostand's anomaly P in water frogs. Parasit Vectors 2020; 13:381. [PMID: 32727553 PMCID: PMC7391616 DOI: 10.1186/s13071-020-04256-2] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2020] [Accepted: 07/21/2020] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Cases of polydactyly in natural populations of amphibians have attracted great interest from biologists. At the end of the 1940s, the French biologist Jean Rostand discovered a polymorphic syndrome in some water frog (Anura: Pelophylax) populations that included polydactyly and some severe morphological anomalies (he called it 'anomaly P'). The cause of this anomaly remains unknown for 70 years. In a previous study, we obtained anomaly P in the laboratory in tadpoles of water frogs that developed together with molluscs Planorbarius corneus (Mollusca: Gastropoda) collected in the field. We thus proposed the 'trematode hypothesis', according to which the infectious agent responsible for anomaly P is a trematode species. METHODS Metacercariae from tadpoles with anomaly P were identified using ITS2 gene sequencing as Strigea robusta (Trematoda: Strigeidae). To verify teratogenic features of the species, cercariae of S. robusta were tested for the possibility to cause anomalies. Identification of cercariae species was made using morphological and molecular methods (sequencing of ITS2 and 28S rRNA). The tadpoles were exposed to parasites at four doses of cercariae (control, low, medium and high) and divided into two groups: "early" (at 25-27 Gosner stages) and "late" (at 29-34 Gosner stages) exposure. RESULTS A total of 58 (72.5%) tadpoles survived until metamorphosis under the dose-dependent experiment with the trematode S. robusta. Differences in the survival rates were observed between the exposed and unexposed tadpoles both in the group of "early" tadpoles and "late" tadpoles. The exposure of tadpoles to the cercariae of S. robusta induced anomaly P in 82% of surviving tadpoles. The severe forms developed only in "early" stages under all doses of cercariae exposure. Polydactyly predominantly developed in the "late" stages; under a light exposure dose, polydactyly also developed in "early" tadpoles. Laboratory-hatched tadpoles reared together with infected snails had different rates of survival and complexity of deformations associated with the period of coexistence. CONCLUSIONS The experiments with direct cercariae exposure provide compelling evidence that S. robusta leads to anomaly P in tadpoles of water frogs. The manifestation of anomaly P turned out to be dependent on the stage of development, cercariae dose, and the location of the cysts.
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Affiliation(s)
| | - Ivan V. Bashinskiy
- A.N. Severtsov Institute of Ecology and Evolution, Russian Academy of Sciences, 119071 Moscow, Russia
| | - Spartak N. Litvinchuk
- Institute of Cytology, Russian Academy of Sciences, 194064 St. Petersburg, Russia
- Dagestan State University, 3367000 Makhachkala, Russia
| | | | | | - Leonid A. Neymark
- A.N. Severtsov Institute of Ecology and Evolution, Russian Academy of Sciences, 119071 Moscow, Russia
| | | | - Vitalij V. Osipov
- Privolzhskaya Lesosteppe State Nature Reserve, 440031 Penza, Russia
- Russian Federal Research Institute of Fisheries and Oceanography, 410002 Saratov, Russia
| | | | - Alain Dubois
- Muséum National d’Histoire Naturelle, Institut Systématique, Evolution, Biodiversité, 75005 Paris, France
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8
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Isaak-Delgado AB, López-Díaz O, Romero-Callejas E, Martínez-Hernández F, Muñoz-García CI, Villalobos G, Rendón-Franco E. Morphological and molecular characteristics of hemoparasites in vaillant's frogs (Lithobates vaillanti). Parasitol Res 2020; 119:1891-1901. [PMID: 32382990 DOI: 10.1007/s00436-020-06689-1] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2019] [Accepted: 04/15/2020] [Indexed: 11/25/2022]
Abstract
Amphibian populations are declining around the world, and the main reasons are the environmental changes and pathogens. However, there are few studies addressing the interaction and impact of the different pathogens that affect amphibians, such as hemoparasites. These parasites had been described as common in some amphibian species, but unfortunately, their description and characterization are unclear and scarcely spread. The objective of the present study was to evaluate the morphological and molecular characterization of hemoparasites present in vaillant's frogs. Seven frogs of Lithobates vaillanti were captured at the biological station La Florida in Tabasco, Mexico. Blood smears were performed, and results show that 100% of the animals have hemoparasites. Three types of hemoparasites were found. Eighty-five percent of the frogs were positive to Hepatozoon sp., 57% to Lankesterella sp., and 28% to Trypanosoma sp. According to the molecular analysis of the obtained sequences of Trypanosoma sp. and Hepatozoon sp., both protozoans were positioned in between the clusters of parasites of different geographical regions. Nevertheless, no species names were assigned to any of these parasites because more sequences and analysis are needed.
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Affiliation(s)
- Ana Belem Isaak-Delgado
- Departamento de Parasitología, Facultad de Medicina Veterinaria y Zootecnia, Universidad Nacional Autónoma de México, Ciudad de Mexico, Mexico
| | - Osvaldo López-Díaz
- Departamento de Producción Agrícola y Animal, Universidad Autónoma Metropolitana-Unidad Xochimilco, Ciudad de Mexico, Mexico
| | - Evangelina Romero-Callejas
- Departamento de Parasitología, Facultad de Medicina Veterinaria y Zootecnia, Universidad Nacional Autónoma de México, Ciudad de Mexico, Mexico
| | | | - Claudia I Muñoz-García
- Departamento de Producción Agrícola y Animal, Universidad Autónoma Metropolitana-Unidad Xochimilco, Ciudad de Mexico, Mexico
| | - Guiehdani Villalobos
- Departamento de Agentes Patógenos, Hospital General Dr. Manuel Gea González, Ciudad de Mexico, Mexico.
| | - Emilio Rendón-Franco
- Departamento de Producción Agrícola y Animal, Universidad Autónoma Metropolitana-Unidad Xochimilco, Ciudad de Mexico, Mexico.
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9
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Tung A, Levin M. Extra-genomic instructive influences in morphogenesis: A review of external signals that regulate growth and form. Dev Biol 2020; 461:1-12. [PMID: 31981561 DOI: 10.1016/j.ydbio.2020.01.010] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/03/2019] [Revised: 01/21/2020] [Accepted: 01/21/2020] [Indexed: 12/18/2022]
Abstract
Embryonic development and regeneration accomplish a remarkable feat: individual cells work together to create or repair complex anatomical structures. What is the source of the instructive signals that specify these invariant and robust organ-level outcomes? The most frequently studied source of morphogenetic control is the host genome and its transcriptional circuits. However, it is now apparent that significant information affecting patterning also arrives from outside of the body. Both biotic and physical factors, including temperature and various molecular signals emanating from pathogens, commensals, and conspecific organisms, affect developmental outcomes. Here, we review examples in which anatomical patterning decisions are strongly impacted by lateral signals that originate from outside of the zygotic genome. The endogenous pathways targeted by these influences often show transgenerational effects, enabling them to shape the evolution of anatomies even faster than traditional Baldwin-type assimilation. We also discuss recent advances in the biophysics of morphogenetic controls and speculate on additional sources of important patterning information which could be exploited to better understand the evolution of bodies and to design novel approaches for regenerative medicine.
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Affiliation(s)
- Angela Tung
- Department of Biology and Allen Discovery Center at Tufts University, Medford, MA, USA
| | - Michael Levin
- Department of Biology and Allen Discovery Center at Tufts University, Medford, MA, USA; Wyss Institute for Biologically Inspired Engineering, Harvard University, Boston, MA, USA.
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10
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Danto M, Witzmann F, Fröbisch NB. Osseous pathologies in the lungless salamander
Desmognathus fuscus
(Plethodontidae). ACTA ZOOL-STOCKHOLM 2020. [DOI: 10.1111/azo.12331] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Affiliation(s)
- Marylène Danto
- Museum für Naturkunde Leibniz‐Institut für Evolutions‐ und Biodiversitätsforschung Berlin Germany
| | - Florian Witzmann
- Museum für Naturkunde Leibniz‐Institut für Evolutions‐ und Biodiversitätsforschung Berlin Germany
| | - Nadia B. Fröbisch
- Museum für Naturkunde Leibniz‐Institut für Evolutions‐ und Biodiversitätsforschung Berlin Germany
- Department of Biology Humboldt Universität zu Berlin Berlin Germany
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11
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Pathirana N, Meegaskumbura M, Rajakaruna R. Host resistance and tolerance to parasitism: development-dependent fitness consequences in Common Hourglass Tree Frog (Polypedates cruciger) tadpoles exposed to two larval trematodes. CAN J ZOOL 2019. [DOI: 10.1139/cjz-2018-0126] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Tolerance and resistance to parasites are defense strategies of host organisms. Here, we tested the development-dependent tolerance and resistance of Polypedates cruciger Blyth, 1852 tadpoles to trematode infection. We exposed the tadpoles at Gosner stages 27, 28–29, and 30–31 to two types of cercariae (furcocercous and pleurolophocercous cercariae of Acanthostomum burminis (Bhalerao, 1926)) under laboratory conditions. To determine tolerance (the ability of a host to limit health effects of a given parasite load), we exposed the tadpoles until all cercariae penetrated the host. As a measure of determining resistance, we exposed tadpoles to cercariae for a limited time and counted the number of cercariae penetrating the tadpoles. The survival of tadpoles exposed at early stages was significantly lower than that of tadpoles exposed at later stages (mixed-effect model, p < 0.05), suggesting an age-dependent tolerance to parasitism. Tadpoles exposed at early stages were also smaller, took longer to metamorphosis, showed lower resistance to parasitism (ANOVA, p < 0.001), and developed axial malformations. In the resistance experiment, fewer parasites penetrated later stage tadpoles than early stage tadpoles. Tadpoles of P. cruciger showed a development-dependent tolerance and resistance to parasitism, resulting in greater survival and fewer malformations when parasitism occurs at late stages.
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Affiliation(s)
- N.U.K. Pathirana
- Department of Zoology, University of Peradeniya, Peradeniya 20400, Sri Lanka
- Postgraduate Institute of Science, University of Peradeniya, Peradeniya 20400, Sri Lanka
- Freshwater Fish Group and Fish Health Unit, Centre for Sustainable Aquatic Ecosystems, School of Veterinary and Life Sciences, Murdoch University, Murdoch, Western Australia 6150, Australia
| | - M. Meegaskumbura
- Guangxi Key Laboratory of Forest Ecology and Conservation, College of Forestry, Guangxi University, Nanning, Guangxi 530004, People’s Republic of China
- Department of Molecular Biology and Biotechnology, University of Peradeniya, Peradeniya 20400, Sri Lanka
| | - R.S. Rajakaruna
- Department of Zoology, University of Peradeniya, Peradeniya 20400, Sri Lanka
- Postgraduate Institute of Science, University of Peradeniya, Peradeniya 20400, Sri Lanka
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12
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Bower DS, Brannelly LA, McDonald CA, Webb RJ, Greenspan SE, Vickers M, Gardner MG, Greenlees MJ. A review of the role of parasites in the ecology of reptiles and amphibians. AUSTRAL ECOL 2018. [DOI: 10.1111/aec.12695] [Citation(s) in RCA: 31] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Affiliation(s)
- Deborah S. Bower
- College of Science and Engineering; James Cook University; Townsville Queensland 4811 Australia
- School of Environmental and Rural Science; University of New England; Armidale New South Wales Australia
| | - Laura A. Brannelly
- Department of Biological Sciences; University of Pittsburgh; Pittsburgh Pennsylvania USA
| | - Cait A. McDonald
- Department of Ecology and Evolutionary Biology; Cornell University; Ithaca New York USA
| | - Rebecca J. Webb
- College of Public Health, Medical and Veterinary Sciences; James Cook University; Townsville Queensland Australia
| | - Sasha E. Greenspan
- Department of Biological Sciences; University of Alabama; Tuscaloosa Alabama USA
| | - Mathew Vickers
- College of Science and Engineering; James Cook University; Townsville Queensland 4811 Australia
| | - Michael G. Gardner
- College of Science and Engineering; Flinders University; Adelaide South Australia Australia
- Evolutionary Biology Unit; South Australian Museum; Adelaide South Australia Australia
| | - Matthew J. Greenlees
- School of Life and Environmental Sciences; University of Sydney; Sydney New South Wales Australia
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13
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Morsy K, Mohamed SA, Abdel-Ghaffar F, El-Fayoumi H, Abdel-Haleem H. Rhabdias bufonis (Rhabdiasidae) from the lung of the African common toad, Amietophrynus regularis (Bufonidae) in Egypt: new data on the basis of light and scanning electron microscopic study. PeerJ 2018; 6:e5328. [PMID: 30042901 PMCID: PMC6055686 DOI: 10.7717/peerj.5328] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/08/2018] [Accepted: 07/06/2018] [Indexed: 11/20/2022] Open
Abstract
Background and Aims Rhabdias sp. (Rhabdiasidae) is a nematode parasite of family Rhabdiasidae infecting the lung of amphibians. The present study provides new morphological details for Rhabdias bufonis isolated from the lungs of the African common toad, Amietophrynus regularis based on observations of light and scanning electron microscopy (SEM). Methods Forty specimens were collected from its natural habitat: the damp, moist fields and gardens at Giza governorate, Egypt. Worms were isolated from the lungs, fixed and then preserved. They were examined using light and SEM with further line drawings. Results Fourteen specimens (35%) were found to harbor Rhabdias with an intensity of three to five worms per host. Bodies of the gravid females were elongated, slender, measured 3.22–9.86 (5.64 ± 0.03) long and 0.09–0.48 (0.23 ± 0.02) wide at mid-length. Buccal capsule was with cylindrical lumen and sclerotized walls. Ovaries were almost straight. The uteri were located anterior and posterior to the vulva. Uterus were filled with a large number of eggs (17–42). Eggs were oval in shape and some of them were with fully developed larvae inside. The tail was comparatively short, gradually tapered. SEM showed that worms possessed an oval anterior end with a simple, slit like oral opening. The lipless edges of the mouth opening were bordered with tiny cuticular elevations, radiated outwards. Two pairs of submedian cephalic papillae were observed around the oral opening as well as two amphids. Conclusion The current study presents new morphological details for R. bufonis isolated from the African common toad. Also, the morphology of the slit-like mouth opening, the two pairs of cephalic papillae, two amphids and the three pairs of cuticular elevations supporting the area around mouth opening were investigated.
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Affiliation(s)
- Kareem Morsy
- Department of Biology, College of Science, King Khalid University, Abha, Saudi Arabia.,Department of Zoology, Faculty of Science, Cairo University, Cairo, Egypt
| | - Sara Ali Mohamed
- Departement of Zoology, Faculty of Science, Beni Suef University, Beni Suef, Egypt
| | | | - Hoda El-Fayoumi
- Departement of Zoology, Faculty of Science, Beni Suef University, Beni Suef, Egypt
| | - Heba Abdel-Haleem
- Departement of Zoology, Faculty of Science, Beni Suef University, Beni Suef, Egypt
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Men Q, Han H, Zhao Q, Xia W, Dong H, Zhu S, Wang Z, Li C, Zhu X, Huang B. The prevalence of helminth parasites in Pelophylax nigromaculatus (Anura: Ranidae) from Shanghai, China. Acta Parasitol 2016; 61:802-807. [PMID: 27787210 DOI: 10.1515/ap-2016-0111] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2016] [Accepted: 07/08/2016] [Indexed: 11/15/2022]
Abstract
Parasites are ubiquitous members of biotic communities. To investigate the infective status of helminth parasites in Pelophylax nigromaculatus from Shanghai, 90 frogs were collected from July 2013 to July 2014 and examined for the presence of internal parasites. Of these, 86.67% (78/90) of frogs were infected with parasites, the total helminth intensity within infected frogs ranged from 1 to 367, and the mean intensity was 28.49. The infection rates and intensities were 78.89% and 22.89 for trematodes, 50.00% and 5.24 for nematodes, 13.33% and 3.92 for cestodes, and 41.11% and 8.49 for acanthocephalas, respectively. The majority (60.04%) of parasites were parasitic in the intestine, followed by urinary bladder (24.8%) and lungs (7.38%). Based on morphological features, 13 different species of helminth, including 9 undetermined species, were identified. The infective status of different species was significantly different. The most prevalent species were Diplodiscus nigromaculati (64.44%), Diplodiscus sp. (37.78%), Pomphorhynchus sp. (35.56%), Strongyloides sp. (33.33%). The mean infection intensity of Diplorchis nigromaculatus (139.25) was higher than the others' species ranged from 3.57-14.63. This is the first reported discovery of Pomphorhynchus sp. (Pomphorhynchidae Yamaguti, 1939) in frogs from China. These data provide the foundation for further analyses of parasites in this and other species of amphibians.
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Roberts C, Dickinson T. Ribeiroia ondatrae causes limb abnormalities in a Canadian amphibian community. CAN J ZOOL 2012. [DOI: 10.1139/z2012-050] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
A parasitic flatworm ( Ribeiroia ondatrae Price, 1931) is known to cause severe limb abnormalities and high mortality levels in American amphibian populations. The distributional pattern of this parasite—its main dispersal agent being birds—correlates with the boundaries of migratory flyways in the USA. Yet thus far, R. ondatrae have not been found in Canadian amphibians, which is surprising, considering that said flyways extend well into northern Canada. In this study, we report on a lake in British Columbia that is known to support amphibians with abnormalities similar to those induced by R. ondatrae. To determine if the parasite was present and if it was the cause of the abnormalities, we collected and necropsied metamorphs of the Columbia Spotted Frog ( Rana luteiventris Thompson, 1913) and the Pacific Chorus Frog ( Pseudacris regilla (Baird and Girard, 1852)), and we set up field enclosures to protect larvae from R. ondatrae. Abnormality levels were high in both species (>20%), with the vast majority being found in close proximity to the metacercariae of R. ondatrae. Moreover, the types of abnormalities closely matched those previously recorded in field and laboratory exposures of amphibians to R. ondatrae. Finally, larvae that developed in the same lake, but were protected from R. ondatrae by an enclosure, did not develop abnormalities. Collectively, these results demonstrate that R. ondatrae are both present in an amphibian community in Canada and responsible for causing limb abnormalities.
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Affiliation(s)
- C.D. Roberts
- Department of Biology, Thompson Rivers University, Kamloops, BC V2C 0C8, Canada
| | - T.E. Dickinson
- Department of Biology, Thompson Rivers University, Kamloops, BC V2C 0C8, Canada
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Hartson RB, Orlofske SA, Melin VE, Dillon RT, Johnson PTJ. Land use and wetland spatial position jointly determine amphibian parasite communities. ECOHEALTH 2011; 8:485-500. [PMID: 22071719 DOI: 10.1007/s10393-011-0715-9] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/02/2010] [Revised: 09/29/2011] [Accepted: 10/10/2011] [Indexed: 05/31/2023]
Abstract
Land use change is one of the most commonly cited contributing factors to infectious disease emergence, yet the mechanisms responsible for such changes and the spatial scales at which they operate are rarely identified. The distributions of parasites with complex life cycles depend on interactions between multiple host species, suggesting the net effects of land use on infection patterns may be difficult to predict a priori. Here, we used an information-theoretic approach to evaluate the importance of land use and spatial scale (local, watershed, and regional) in determining the presence and abundance of multi-host trematodes of amphibians. Among 40 wetlands and 160 hosts sampled, trematode abundance, species richness, and the presence and abundance of pathogenic species were strongly influenced by variables at the watershed and regional scales. Based on model averaging results, overall parasite richness and abundance were higher in forested wetlands than in agricultural areas; however, this pattern was influenced by a wetland's proximity to the Mississippi Flyway at the regional scale. These patterns likely reflect the activity of trematode definitive hosts, such as mammals and especially birds, such that infections decreased with increasing distance from the Mississippi River. Interestingly, despite lower mean infections, agricultural wetlands had higher variances and maximum infections. At the wetland scale, phosphorus concentrations and the abundances of intermediate hosts, such as snails and larval amphibians, positively affected parasite distributions. Taken together, these results contribute to our understanding of how altered landscapes affect parasite communities and inform further research on the environmental drivers of amphibian parasite infections.
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Affiliation(s)
- Richard B Hartson
- Department of Water Resources, University of Idaho, Moscow, ID 83843, USA
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Skelly DK, Benard MF. Mystery unsolved: missing limbs in deformed amphibians. JOURNAL OF EXPERIMENTAL ZOOLOGY PART B-MOLECULAR AND DEVELOPMENTAL EVOLUTION 2010; 314:179-81. [PMID: 19950330 DOI: 10.1002/jez.b.21330] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
Ballengee and Sessions (2009) claim that predatory attacks by small predators such as Sympetrum dragonfly larvae are sufficient to explain amphibian limb deformities in which the limb is partly or completely missing. This deformity type, the most common in nature, is not well explained by Ribeiroia infection which has also been nominated as a mechanism for limb deformities. We argue that the conclusions of the Ballanegee and Sessions study are not well founded. In part this is because the authors have provided no quantitative analysis of the association between limb deformities and predator densities. Our own data on frequencies of limb deformities suggest that missing hind limbs are often extremely rare even when Sympetrum and other small predators are common. While predatory attacks may contribute to observations of limb deformities, further study will be required to elucidate their role; other potential mechanisms deserve study as well. It is premature, and counterproductive, to draw any conclusions regarding the mechanisms behind the most common limb deformities recorded in natural populations.
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Affiliation(s)
- David K Skelly
- School of Forestry & Environmental Studies, Yale University, New Haven, Connecticut 06511, USA.
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Sessions SK, Ballengée B. Explanations for deformed frogs: plenty of research left to do (a response to Skelly and Benard). JOURNAL OF EXPERIMENTAL ZOOLOGY PART B-MOLECULAR AND DEVELOPMENTAL EVOLUTION 2010; 314:341-6. [DOI: 10.1002/jez.b.21351] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
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Ballengée B, Sessions SK. Explanation for missing limbs in deformed amphibians. JOURNAL OF EXPERIMENTAL ZOOLOGY PART B-MOLECULAR AND DEVELOPMENTAL EVOLUTION 2009; 312:770-9. [DOI: 10.1002/jez.b.21296] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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20
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Pugener LA, Maglia AM. Skeletal morphogenesis of the vertebral column of the miniature hylid frog Acris crepitans, with comments on anomalies. J Morphol 2009; 270:52-69. [PMID: 18946872 DOI: 10.1002/jmor.10665] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
Although the vertebral columns of anurans have received much study in the last 150 years, few detailed descriptions exist of the skeletal morphogenesis of this anatomical unit. Herein, the ontogeny of the vertebral skeleton of the hylid frog Acris crepitans is described based on cleared and double-stained specimens, radiographs, and 3D reconstructions generated from synchrotron microCT scans. The adult axial formula is 1-7-1-1, and the vertebral centra are epichordal and procoelous. The neural arches are nonimbricate, and there is a medial articulation between the laminae of Presacrals I and II. Free ribs are absent. The sacral diapophyses are uniform in width or slightly expanded distally. The urostyle is slender, round in cross section, and about equal in length to the presacral region. Presacral vertebrae are the first to form, developing in a cephalic-to-caudal sequence. However, development and growth are decoupled and growth is fastest initially in the posterior presacrals and sacrum. In addition, there is a time lag between the formation of the presacral/sacral region and the postsacral region. More than 8.5% of the specimens examined have vertebral anomalies, and about 50% display small variants from the typical vertebral column morphology. However, these malformations do not seem to have been so severe as to have affected survival.
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Affiliation(s)
- L Analía Pugener
- Department of Biological Sciences, Missouri University of Science and Technology, Rolla, Missouri 65409, USA.
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21
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The role of trematode parasites in larval anuran communities: an aquatic ecologist’s guide to the major players. Oecologia 2009; 161:371-85. [DOI: 10.1007/s00442-009-1388-8] [Citation(s) in RCA: 51] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2008] [Accepted: 05/22/2009] [Indexed: 11/29/2022]
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Williams RN, Bos DH, Gopurenko D, Dewoody JA. Amphibian malformations and inbreeding. Biol Lett 2008; 4:549-52. [PMID: 18593670 PMCID: PMC2610075 DOI: 10.1098/rsbl.2008.0233] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/08/2008] [Revised: 06/03/2008] [Accepted: 06/10/2008] [Indexed: 11/12/2022] Open
Abstract
Inbreeding may lead to morphological malformations in a wide variety of taxa. We used genetic markers to evaluate whether malformed urodeles were more inbred and/or had less genetic diversity than normal salamanders. We captured 687 adult and 1,259 larval tiger salamanders (Ambystoma tigrinum tigrinum), assessed each individual for gross malformations, and surveyed genetic variation among malformed and normal individuals using both cytoplasmic and nuclear markers. The most common malformations in both adults and larvae were brachydactyly, ectrodactyly and polyphalangy. The overall frequency of adults with malformations was 0.078 compared to 0.081 in larval samples. Genetic diversity was high in both normal and malformed salamanders, and there were no significant difference in measures of inbreeding (f and F), allele frequencies, mean individual heterozygosity or mean internal relatedness. Environmental contaminants or other extrinsic factors may lead to genome alternations that ultimately cause malformations, but our data indicate that inbreeding is not a causal mechanism.
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Affiliation(s)
- Rod N Williams
- Department of Forestry and Natural Resources, Purdue University, West Lafayette, IN 47907, USA.
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Johnson PTJ, Hartson RB. All hosts are not equal: explaining differential patterns of malformations in an amphibian community. J Anim Ecol 2008; 78:191-201. [PMID: 18671806 DOI: 10.1111/j.1365-2656.2008.01455.x] [Citation(s) in RCA: 46] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
1. Within a community, different host species often exhibit broad variation in sensitivity to infection and disease. Because such differences can influence the strength and outcome of community interactions, it is essential to understand differential disease patterns and identify the mechanisms responsible. 2. In North American wetlands, amphibian species often exhibit extraordinary differences in the frequency of limb malformations induced by the digenetic trematode, Ribeiroia ondatrae. By coupling field studies with parasite exposure experiments, we evaluated whether such patterns were due to differences in (i) parasite encounter rate, (ii) infection establishment, or (iii) parasite persistence within hosts. 3. Field results underscored the broad variation in malformations and infection between host species; while nearly 60% (n = 618) of emerging American toads exhibited severe limb deformities such as bony triangles, skin webbings and missing limbs, fewer than 4% (n = 251) of Eastern gray treefrogs from the same pond were abnormal. Despite similarities in the phenology and larval development period of these species, they differed sharply in Ribeiroia infection. On average, toads supported 75x more metacercariae than did metamorphic treefrogs. 4. Experimental exposures of larval toads and treefrogs to a realistic range of Ribeiroia cercariae revealed strong differences in the sensitivity of these species to infection; exposed toads suffered elevated mortality (up to 95%), delayed metamorphosis, and severe limb malformations consistent with field observations. Treefrogs, in contrast, exhibited limited mortality and no malformations, regardless of exposure level. Ribeiroia cercariae were substantially less successful in locating and infecting Hyla versicolor larvae. 5. Our results indicate that the observed differences in infection and malformations owe to a lower ability of Ribeiroia cercariae to both find and establish within larval treefrogs, possibly stemming from a heightened immune response to infection. Because Ribeiroia is a highly pathogenic parasite with negative effects on larval and metamorphic amphibian survival, variation in infection resistance among species could have important implications for understanding patterns of species co-occurrence, competition, and community diversity.
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Affiliation(s)
- Pieter T J Johnson
- Ecology and Evolutionary Biology, University of Colorado, Ramaley N122, Campus Box 334, Boulder, CO 80309, USA.
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Rajakaruna RS, Piyatissa PMJR, Jayawardena UA, Navaratne AN, Amerasinghe PH. Trematode infection induced malformations in the common hourglass treefrogs. J Zool (1987) 2008. [DOI: 10.1111/j.1469-7998.2008.00416.x] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- R. S. Rajakaruna
- Department of Zoology, University of Peradeniya, Peradeniya, Sri Lanka
| | - P. M. J. R. Piyatissa
- Department of Zoology, University of Peradeniya, Peradeniya, Sri Lanka
- Postgraduate Institute of Science, University of Peradeniya, Peradeniya, Sri Lanka
| | - U. A. Jayawardena
- Department of Zoology, University of Peradeniya, Peradeniya, Sri Lanka
- Postgraduate Institute of Science, University of Peradeniya, Peradeniya, Sri Lanka
| | - A. N. Navaratne
- Department of Chemistry, University of Peradeniya, Peradeniya, Sri Lanka
| | - P. H. Amerasinghe
- International Water Management Institute, C/o ICRISAT, Patancheru, Hyderabad, Andhra Pradesh, India
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King KC, Gendron AD, McLaughlin JD, Giroux I, Brousseau P, Cyr D, Ruby SM, Fournier M, Marcogliese DJ. Short-Term Seasonal Changes in Parasite Community Structure in Northern Leopard Froglets (Rana pipiens) Inhabiting Agricultural Wetlands. J Parasitol 2008; 94:13-22. [DOI: 10.1645/ge-1233.1] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022] Open
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Taylor B, Skelly D, Demarchis LK, Slade MD, Galusha D, Rabinowitz PM. Proximity to pollution sources and risk of amphibian limb malformation. ENVIRONMENTAL HEALTH PERSPECTIVES 2005; 113:1497-501. [PMID: 16263502 PMCID: PMC1310909 DOI: 10.1289/ehp.7585] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/05/2023]
Abstract
The cause of limb deformities in wild amphibian populations remains unclear, even though the apparent increase in prevalence of this condition may have implications for human health. Few studies have simultaneously assessed the effect of multiple exposures on the risk of limb deformities. In a cross-sectional survey of 5,264 hylid and ranid metamorphs in 42 Vermont wetlands, we assessed independent risk factors for nontraumatic limb malformation. The rate of nontraumatic limb malformation varied by location from 0 to 10.2%. Analysis of a subsample did not demonstrate any evidence of infection with the parasite Ribeiroia. We used geographic information system (GIS) land-use/land-cover data to validate field observations of land use in the proximity of study wetlands. In a multiple logistic regression model that included land use as well as developmental stage, genus, and water-quality measures, proximity to agricultural land use was associated with an increased risk of limb malformation (odds ratio = 2.26; 95% confidence interval, 1.42-3.58; p < 0.001). The overall discriminant power of the statistical model was high (C = 0.79). These findings from one of the largest systematic surveys to date provide support for the role of chemical toxicants in the development of amphibian limb malformation and demonstrate the value of an epidemiologic approach to this problem.
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Affiliation(s)
- Brynn Taylor
- School of Forestry and Environmental Studies, Yale University, New Haven, Connecticut, USA
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Taylor CN, Oseen KL, Wassersug RJ. On the behavioural response ofRanaandBufotadpoles to echinostomatoid cercariae: implications to synergistic factors influencing trematode infections in anurans. CAN J ZOOL 2004. [DOI: 10.1139/z04-037] [Citation(s) in RCA: 45] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
We used high-speed videography of staged encounters between tadpoles of either Bufo americanus Holbrook, 1836 or Rana sylvatica LeConte, 1825 and Echinostoma Rudolphi, 1809 cercariae to understand why echinostomatoid trematodes, such as species from the genera Echinostoma and Ribeiroia Travassos, 1939 (implicated in anuran limb deformities), attack specific anatomical regions of tadpoles. Bufo and Rana tadpoles can shed cercariae on their skin from some parts of their body more easily than others. In particular, cercariae that enter the "dead-water zone" at the junction of a tadpole's body and tail appear particularly difficult for tadpoles to brush off. Cercariae that reach this recess can easily enter the inguinal region of tadpoles (as do Ribeiroia spp.) or ascend the tadpole's cloaca (as do Echinostoma spp.). When tadpoles sense cercariae contacting their skin they make explosive movements to shed those parasites. Factors that reduce tadpoles' activity, such as predator threat or certain pesticides, may increase a tadpole's susceptibility to echinostomatoid infection. Because Bufo tadpoles are unpalatable to many predators, they can afford to make more conspicuous evasive maneuvers than Rana tadpoles, and do so in the laboratory. Bufo tadpoles in the field also have a lower rate and different anatomical distribution pattern of Ribeiroia infection than Rana tadpoles. Factors that reduce tadpole activity in the field may act synergistically to increase parasite loads and subsequent deformities in anurans.
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Schotthoefer AM, Koehler AV, Meteyer CU, Cole RA. Influence of Ribeiroia ondatrae (Trematoda: Digenea) infection on limb development and survival of northern leopard frogs (Rana pipiens): effects of host stage and parasite-exposure level. CAN J ZOOL 2003. [DOI: 10.1139/z03-099] [Citation(s) in RCA: 56] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Recent evidence suggests that infection by larvae of the trematode Ribeiroia ondatrae accounts for a significant proportion of limb malformations currently observed in amphibian populations of North America. However, the effects of R. ondatrae infection on northern leopard frogs (Rana pipiens), one of the species most frequently reported with malformations, have not been adequately explored. Moreover, the risk factors associated with R. ondatrae-induced malformations have not been clearly identified. We examined the effects of timing of infection on tadpole survival and limb development. Rana pipiens tadpoles were individually exposed to R. ondatrae cercariae at the pre-limb-bud (Gosner stages 24 and 25), limb-bud (Gosner stages 27 and 28), or paddle (Gosner stages 3133) stages of development and monitored through metamorphosis. The effects of infection were stage-specific. Infections acquired at the pre-limb-bud stage resulted in a high mortality rate (47.597.5%), whereas tadpoles infected at the limb-bud stage displayed a high malformation rate (16% overall), and the magnitude of effects increased with the level of exposure to cercariae. In contrast, infections acquired at the paddle stage had no effect on limb development or tadpole survival, which suggests that the timing of R. ondatrae infection in relation to the stage structure of tadpole populations in the wild is an important determinant of the degree to which populations are affected by R. ondatrae.
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Stopper GF, Hecker L, Franssen RA, Sessions SK. How trematodes cause limb deformities in amphibians. THE JOURNAL OF EXPERIMENTAL ZOOLOGY 2002; 294:252-63. [PMID: 12362431 DOI: 10.1002/jez.10173] [Citation(s) in RCA: 51] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
We used trematode cyst infestation to induce limb deformities in two species of frogs of the genus Rana and compared them to deformities induced by surgical limb bud rotations. The specific deformities produced by both treatments closely resemble those of wild-caught deformed amphibians and are consistent with a known developmental response to disruption of the spatial organization of cells in developing limb buds. Histological analysis showed that trematode cysts cause massive disruption and abnormal cellular growth involving the limb buds of infected individuals. Our results indicate that trematode cyst infestation causes deformities in frogs by perturbation of the positional relationships of cells in developing limb buds. The crippling effects of cyst-infection on frogs may reflect complex co-evolutionary interactions among trematodes, frogs, and other hosts in the trematode's life cycle.
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Affiliation(s)
- Geffrey F Stopper
- Department of Ecology and Evolutionary Biology, Yale University, New Haven, Connecticut 06520-8106, USA
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