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Ujszegi J, Ujhegyi N, Balogh E, Mikó Z, Kásler A, Hettyey A, Bókony V. No sex-dependent mortality in an amphibian upon infection with the chytrid fungus, Batrachochytrium dendrobatidis. Ecol Evol 2024; 14:e70219. [PMID: 39219568 PMCID: PMC11362217 DOI: 10.1002/ece3.70219] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/21/2024] [Revised: 08/07/2024] [Accepted: 08/09/2024] [Indexed: 09/04/2024] Open
Abstract
One of the major factors driving the currently ongoing biodiversity crisis is the anthropogenic spread of infectious diseases. Diseases can have conspicuous consequences, such as mass mortality events, but may also exert covert but similarly severe effects, such as sex ratio distortion via sex-biased mortality. Chytridiomycosis, caused by the fungal pathogen Batrachochytrium dendrobatidis (Bd) is among the most important threats to amphibian biodiversity. Yet, whether Bd infection can skew sex ratios in amphibians is currently unknown, although such a hidden effect may cause the already dwindling amphibian populations to collapse. To investigate this possibility, we collected common toad (Bufo bufo) tadpoles from a natural habitat in Hungary and continuously treated them until metamorphosis with sterile Bd culture medium (control), or a liquid culture of a Hungarian or a Spanish Bd isolate. Bd prevalence was high in animals that died during the experiment but was almost zero in individuals that survived until the end of the experiment. Both Bd treatments significantly reduced survival after metamorphosis, but we did not observe sex-dependent mortality in either treatment. However, a small number of genotypically female individuals developed male phenotype (testes) in the Spanish Bd isolate treatment. Therefore, future research is needed to ascertain if larval Bd infection can affect sex ratio in common toads through female-to-male sex reversal.
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Affiliation(s)
- János Ujszegi
- Department of Evolutionary Ecology, HUN‐REN Centre for Agricultural ResearchPlant Protection InstituteBudapestHungary
- Department of Systematic Zoology and EcologyELTE Eötvös Loránd UniversityBudapestHungary
| | - Nikolett Ujhegyi
- Department of Evolutionary Ecology, HUN‐REN Centre for Agricultural ResearchPlant Protection InstituteBudapestHungary
| | - Emese Balogh
- Department of Evolutionary Ecology, HUN‐REN Centre for Agricultural ResearchPlant Protection InstituteBudapestHungary
- Department of ZoologyUniversity of Veterinary Medicine BudapestBudapestHungary
| | - Zsanett Mikó
- Department of Evolutionary Ecology, HUN‐REN Centre for Agricultural ResearchPlant Protection InstituteBudapestHungary
| | - Andrea Kásler
- Department of Evolutionary Ecology, HUN‐REN Centre for Agricultural ResearchPlant Protection InstituteBudapestHungary
- Department of Systematic Zoology and EcologyELTE Eötvös Loránd UniversityBudapestHungary
- Doctoral School of Biology, Institute of BiologyELTE Eötvös Loránd UniversityBudapestHungary
| | - Attila Hettyey
- Department of Evolutionary Ecology, HUN‐REN Centre for Agricultural ResearchPlant Protection InstituteBudapestHungary
- Department of Systematic Zoology and EcologyELTE Eötvös Loránd UniversityBudapestHungary
| | - Veronika Bókony
- Department of Evolutionary Ecology, HUN‐REN Centre for Agricultural ResearchPlant Protection InstituteBudapestHungary
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Bókony V, Kalina C, Ujhegyi N, Mikó Z, Lefler KK, Vili N, Gál Z, Gabor CR, Hoffmann OI. Does stress make males? An experiment on the role of glucocorticoids in anuran sex reversal. JOURNAL OF EXPERIMENTAL ZOOLOGY. PART A, ECOLOGICAL AND INTEGRATIVE PHYSIOLOGY 2024; 341:172-181. [PMID: 38155497 DOI: 10.1002/jez.2772] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/08/2023] [Revised: 12/06/2023] [Accepted: 12/11/2023] [Indexed: 12/30/2023]
Abstract
Environmentally sensitive sex determination may help organisms adapt to environmental change but also makes them vulnerable to anthropogenic stressors, with diverse consequences for population dynamics and evolution. The mechanisms translating environmental stimuli to sex are controversial: although several fish experiments supported the mediator role of glucocorticoid hormones, results on some reptiles challenged it. We tested this hypothesis in amphibians by investigating the effect of corticosterone on sex determination in agile frogs (Rana dalmatina). This species is liable to environmental sex reversal whereby genetic females develop into phenotypic males. After exposing tadpoles during sex determination to waterborne corticosterone, the proportion of genetic females with testes or ovotestes increased from 11% to up to 32% at 3 out of 4 concentrations. These differences were not statistically significant except for the group treated with 10 nM corticosterone, and there was no monotonous dose-effect relationship. These findings suggest that corticosterone is unlikely to mediate sex reversal in frogs. Unexpectedly, animals originating from urban habitats had higher sex-reversal and corticosterone-release rates, reduced body mass and development speed, and lower survival compared to individuals collected from woodland habitats. Thus, anthropogenic environments may affect both sex and fitness, and the underlying mechanisms may vary across ectothermic vertebrates.
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Affiliation(s)
- Veronika Bókony
- Department of Evolutionary Ecology, Plant Protection Institute, HUN-REN Centre for Agricultural Research, Budapest, Hungary
- Department of Zoology, University of Veterinary Medicine Budapest, Budapest, Hungary
| | - Csenge Kalina
- Department of Zoology, University of Veterinary Medicine Budapest, Budapest, Hungary
| | - Nikolett Ujhegyi
- Department of Evolutionary Ecology, Plant Protection Institute, HUN-REN Centre for Agricultural Research, Budapest, Hungary
| | - Zsanett Mikó
- Department of Evolutionary Ecology, Plant Protection Institute, HUN-REN Centre for Agricultural Research, Budapest, Hungary
| | - Kinga Katalin Lefler
- Department of Aquaculture, Institute of Agricultural and Environmental Safety, Hungarian University of Agriculture and Life Science, Gödöllő, Hungary
| | - Nóra Vili
- Department of Zoology, University of Veterinary Medicine Budapest, Budapest, Hungary
| | - Zoltán Gál
- Department of Animal Biotechnology, Institute of Genetics and Biotechnology, Hungarian University of Agriculture and Life Science, Gödöllő, Hungary
| | - Caitlin R Gabor
- Department of Biology, Texas State University, San Marcos, Texas, USA
| | - Orsolya Ivett Hoffmann
- Department of Animal Biotechnology, Institute of Genetics and Biotechnology, Hungarian University of Agriculture and Life Science, Gödöllő, Hungary
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Carvalho T, Si C, Clemons RA, Faust E, James TY. Amphibian Hymenochirus boettgeri as an experimental model for infection studies with the chytrid fungus Batrachochytrium dendrobatidis. Virulence 2023; 14:2270252. [PMID: 37823610 PMCID: PMC10614710 DOI: 10.1080/21505594.2023.2270252] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/03/2023] [Accepted: 10/09/2023] [Indexed: 10/13/2023] Open
Abstract
Model organisms are crucial in research as they can provide key insights applicable to other species. This study proposes the use of the amphibian species Hymenochirus boettgeri, widely available through the aquarium trade, as a model organism for the study of chytridiomycosis, a disease caused by the fungus Batrachochytrium dendrobatidis (Bd) and linked to amphibian decline and extinction globally. Currently, no model organisms are used in the study of chytridiomycosis, particularly because of the lack of availability and nonstandardized methods. Thus, laboratories around the world use wild local species to conduct Bd infection experiments, which prevents comparisons between studies and reduces reproducibility. Here, we performed a series of Bd infection assays that showed that H. boettgeri has a dose- and genotype-dependent response, can generalize previous findings on virulence estimates in other species, and can generate reproducible results in replicated experimental conditions. We also provided valuable information regarding H. boettgeri husbandry, including care, housing, reproduction, and heat treatment to eliminate previous Bd infections. Together, our results indicate that H. boettgeri is a powerful and low-ecological-impact system for studying Bd pathogenicity and virulence.
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Affiliation(s)
- Tamilie Carvalho
- Department of Ecology and Evolutionary Biology, University of Michigan, Ann Arbor, MI, USA
| | - Catherine Si
- Department of Ecology and Evolutionary Biology, University of Michigan, Ann Arbor, MI, USA
| | - Rebecca A. Clemons
- Department of Ecology and Evolutionary Biology, University of Michigan, Ann Arbor, MI, USA
| | - Evelyn Faust
- Department of Ecology and Evolutionary Biology, University of Michigan, Ann Arbor, MI, USA
| | - Timothy Y. James
- Department of Ecology and Evolutionary Biology, University of Michigan Herbarium, Ann Arbor, MI, USA
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Nolan N, Hayward MW, Klop-Toker K, Mahony M, Lemckert F, Callen A. Complex Organisms Must Deal with Complex Threats: How Does Amphibian Conservation Deal with Biphasic Life Cycles? Animals (Basel) 2023; 13:ani13101634. [PMID: 37238064 DOI: 10.3390/ani13101634] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/14/2023] [Revised: 05/08/2023] [Accepted: 05/11/2023] [Indexed: 05/28/2023] Open
Abstract
The unprecedented rate of global amphibian decline is attributed to The Anthropocene, with human actions triggering the Sixth Mass Extinction Event. Amphibians have suffered some of the most extreme declines, and their lack of response to conservation actions may reflect challenges faced by taxa that exhibit biphasic life histories. There is an urgent need to ensure that conservation measures are cost-effective and yield positive outcomes. Many conservation actions have failed to meet their intended goals of bolstering populations to ensure the persistence of species into the future. We suggest that past conservation efforts have not considered how different threats influence multiple life stages of amphibians, potentially leading to suboptimal outcomes for their conservation. Our review highlights the multitude of threats amphibians face at each life stage and the conservation actions used to mitigate these threats. We also draw attention to the paucity of studies that have employed multiple actions across more than one life stage. Conservation programs for biphasic amphibians, and the research that guides them, lack a multi-pronged approach to deal with multiple threats across the lifecycle. Conservation management programs must recognise the changing threat landscape for biphasic amphibians to reduce their notoriety as the most threatened vertebrate taxa globally.
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Affiliation(s)
- Nadine Nolan
- Conservation Science Research Group, School of Environmental and Life Sciences, University of Newcastle, Callaghan, NSW 2308, Australia
| | - Matthew W Hayward
- Conservation Science Research Group, School of Environmental and Life Sciences, University of Newcastle, Callaghan, NSW 2308, Australia
| | - Kaya Klop-Toker
- Conservation Science Research Group, School of Environmental and Life Sciences, University of Newcastle, Callaghan, NSW 2308, Australia
| | - Michael Mahony
- Conservation Science Research Group, School of Environmental and Life Sciences, University of Newcastle, Callaghan, NSW 2308, Australia
| | - Frank Lemckert
- Eco Logical Australia Pty Ltd., Perth, WA 6000, Australia
| | - Alex Callen
- Conservation Science Research Group, School of Environmental and Life Sciences, University of Newcastle, Callaghan, NSW 2308, Australia
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Messina S, Costantini D, Eens M. Impacts of rising temperatures and water acidification on the oxidative status and immune system of aquatic ectothermic vertebrates: A meta-analysis. THE SCIENCE OF THE TOTAL ENVIRONMENT 2023; 868:161580. [PMID: 36646226 DOI: 10.1016/j.scitotenv.2023.161580] [Citation(s) in RCA: 8] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/18/2022] [Revised: 12/21/2022] [Accepted: 01/09/2023] [Indexed: 06/17/2023]
Abstract
Species persistence in the Anthropocene is dramatically threatened by global climate change. Large emissions of carbon dioxide (CO2) from human activities are driving increases in mean temperature, intensity of heatwaves, and acidification of oceans and freshwater bodies. Ectotherms are particularly sensitive to CO2-induced stressors, because the rate of their metabolic reactions, as well as their immunological performance, are affected by environmental temperatures and water pH. We reviewed and performed a meta-analysis of 56 studies, involving 1259 effect sizes, that compared oxidative status or immune function metrics between 42 species of ectothermic vertebrates exposed to long-term increased temperatures or water acidification (≥48 h), and those exposed to control parameters resembling natural conditions. We found that CO2-induced stressors enhance levels of molecular oxidative damages in ectotherms, while the activity of antioxidant enzymes was upregulated only at higher temperatures, possibly due to an increased rate of biochemical reactions dependent on the higher ambient temperature. Differently, both temperature and water acidification showed weak impacts on immune function, indicating different direction (increase or decrease) of responses among immune traits. Further, we found that the intensity of temperature treatments (Δ°C) and their duration, enhance the physiological response of ectotherms, pointing to stronger effects of prolonged extreme warming events (i.e., heatwaves) on the oxidative status. Finally, adult individuals showed weaker antioxidant enzymatic responses to an increase in water temperature compared to early life stages, suggesting lower acclimation capacity. Antarctic species showed weaker antioxidant response compared to temperate and tropical species, but level of uncertainty in the antioxidant enzymatic response of Antarctic species was high, thus pairwise comparisons were statistically non-significant. Overall, the results of this meta-analysis indicate that the regulation of oxidative status might be one key mechanism underlying thermal plasticity in aquatic ectothermic vertebrates.
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Affiliation(s)
- Simone Messina
- Behavioural Ecology & Ecophysiology Group, Department of Biology, University of Antwerp, Universiteitsplein 1, 2610 Wilrijk, Belgium; Department of Ecological and Biological Sciences, Tuscia University, Largo dell'Università s.n.c., 01100 Viterbo, Italy.
| | - David Costantini
- Department of Ecological and Biological Sciences, Tuscia University, Largo dell'Università s.n.c., 01100 Viterbo, Italy; Unité Physiologie Moléculaire et Adaptation, UMR 7221, Muséum National d'Histoire Naturelle, CNRS - 7 rue Cuvier, 75005 Paris, France
| | - Marcel Eens
- Behavioural Ecology & Ecophysiology Group, Department of Biology, University of Antwerp, Universiteitsplein 1, 2610 Wilrijk, Belgium
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Nemesházi E, Bókony V. Asymmetrical sex reversal: Does the type of heterogamety predict propensity for sex reversal? Bioessays 2022; 44:e2200039. [PMID: 35543235 DOI: 10.1002/bies.202200039] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/16/2022] [Revised: 04/12/2022] [Accepted: 04/29/2022] [Indexed: 11/10/2022]
Abstract
Sex reversal, a mismatch between phenotypic and genetic sex, can be induced by chemical and thermal insults in ectotherms. Therefore, climate change and environmental pollution may increase sex-reversal frequency in wild populations, with wide-ranging implications for sex ratios, population dynamics, and the evolution of sex determination. We propose that reconsidering the half-century old theory "Witschi's rule" should facilitate understanding the differences between species in sex-reversal propensity and thereby predicting their vulnerability to anthropogenic environmental change. The idea is that sex reversal should be asymmetrical: more likely to occur in the homogametic sex, assuming that sex-reversed heterogametic individuals would produce new genotypes with reduced fitness. A review of the existing evidence shows that while sex reversal can be induced in both homogametic and heterogametic individuals, the latter seem to require stronger stimuli in several cases. We provide guidelines for future studies on sex reversal to facilitate data comparability and reliability.
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Affiliation(s)
- Edina Nemesházi
- Conservation Genetics Research Group, Department of Ecology, University of Veterinary Medicine Budapest, Budapest, Hungary
| | - Veronika Bókony
- Conservation Genetics Research Group, Department of Ecology, University of Veterinary Medicine Budapest, Budapest, Hungary.,Lendület Evolutionary Ecology Research Group, Plant Protection Institute, Centre for Agricultural Research, Eötvös Loránd Research Network, Budapest, Hungary
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