13 research outputs found
Recent Asian origin of chytrid fungi causing global amphibian declines
Globalized infectious diseases are causing species declines worldwide, but their source often remains elusive. We used whole-genome sequencing to solve the spatiotemporal origins of the most devastating panzootic to date, caused by the fungus Batrachochytrium dendrobatidis, a proximate driver of global amphibian declines. We traced the source of B. dendrobatidis to the Korean peninsula, where one lineage, BdASIA-1, exhibits the genetic hallmarks of an ancestral population that seeded the panzootic. We date the emergence of this pathogen to the early 20th century, coinciding with the global expansion of commercial trade in amphibians, and we show that intercontinental transmission is ongoing. Our findings point to East Asia as a geographic hotspot for B. dendrobatidis biodiversity and the original source of these lineages that now parasitize amphibians worldwide
Development and worldwide use of non-lethal, and minimal population-level impact, protocols for the isolation of amphibian chytrid fungi
T.W.J.G., M.C.F., D.S.S., A.L., E.C., F.C.C., J.B., A.A.C., C.M., F.S., B.R.S., S.O., were supported through the Biodiversa project RACE: Risk Assessment of Chytridiomycosis to European Amphibian Biodiversity (NERC standard grant NE/K014455/1 and NE/E006701/1; ANR-08-BDVA-002-03). M.C.F., J.S., C.W., P.G. were supported by the Leverhulme Trust (RPG-2014-273), M.C.F., A.C., C.W. were supported by the Morris Animal Foundation. J.V. was supported by the Bolyai JĂĄnos Research Grant of the Hunagrian Academy of Sciences (BO/00597/14). F.G. and D.G. were supported by the Conservation Leadership Programme Future Conservationist Award. C.S.A. was supported by Fondecyt (No. 1181758). M.C.F. and A.C. were supported by. Mohamed bin Zayed Species Conservation Fund Project (152510704). GMR held a doctoral scholarship (SFRH/BD/69194/2010) from Fundação para a CiĂȘncia e a Tecnologia. L.F.T., C.L., L.P.R. K.R.Z., T.Y.J., T.S.J. were supported by SĂŁo Paulo Research Foundation (FAPESP #2016/25358-3), the National Counsel of Technological and Scientific Development (CNPq #300896/2016â6) and a Catalyzing New International Collaborations grant from the United States NSF (OISE-1159513). C.S.A. was supported by Fondecyt (No. 1181758). T.M.D. was supported by the Royal Geographical Society and the Royal Zoological Society of Scotland. B.W. was supported by the National Research Foundation of Korea (2015R1D1A1A01057282).Peer reviewedPublisher PD
Development and worldwide use of non-lethal, and minimal population-level impact, protocols for the isolation of amphibian chytrid fungi
© The Author(s) 2018.Parasitic chytrid fungi have emerged as a significant threat to amphibian species worldwide, necessitating the development of techniques to isolate these pathogens into culture for research purposes. However, early methods of isolating chytrids from their hosts relied on killing amphibians. We modified a pre-existing protocol for isolating chytrids from infected animals to use toe clips and biopsies from toe webbing rather than euthanizing hosts, and distributed the protocol to researchers as part of the BiodivERsA project RACE; here called the RML protocol. In tandem, we developed a lethal procedure for isolating chytrids from tadpole mouthparts. Reviewing a database of use a decade after their inception, we find that these methods have been applied across 5 continents, 23 countries and in 62 amphibian species. Isolation of chytrids by the non-lethal RML protocol occured in 18% of attempts with 207 fungal isolates and three species of chytrid being recovered. Isolation of chytrids from tadpoles occured in 43% of attempts with 334 fungal isolates of one species (Batrachochytrium dendrobatidis) being recovered. Together, these methods have resulted in a significant reduction and refinement of our use of threatened amphibian species and have improved our ability to work with this group of emerging pathogens.T.W.J.G., M.C.F., D.S.S., A.L., E.C., F.C.C., J.B., A.A.C., C.M., F.S., B.R.S., S.O., were supported through the Biodiversa project RACE: Risk Assessment of Chytridiomycosis to European Amphibian Biodiversity (NERC standard grant NE/K014455/1 and NE/E006701/1; ANR-08-BDVA-002-03). M.C.F., J.S., C.W., P.G. were supported by the Leverhulme Trust (RPG-2014-273), M.C.F., A.C., C.W. were supported by the Morris Animal Foundation. J.V. was supported by the Bolyai JĂĄnos Research Grant of the Hunagrian Academy of Sciences (BO/00597/14). F.G. and D.G. were supported by the Conservation Leadership Programme Future Conservationist Award. C.S.A. was supported by Fondecyt (No. 1181758). M.C.F. and A.C. were supported by. Mohamed bin Zayed Species Conservation Fund Project (152510704). GMR held a doctoral scholarship (SFRH/ BD/69194/2010) from Fundação para a CiĂȘncia e a Tecnologia. L.F.T., C.L., L.P.R. K.R.Z., T.Y.J., T.S.J. were supported by SĂŁo Paulo Research Foundation (FAPESP #2016/25358-3), the National Counsel of Technological and Scientifc Development (CNPq #300896/2016â6) and a Catalyzing New International Collaborations grant from the United States NSF (OISE-1159513). C.S.A. was supported by Fondecyt (No. 1181758). T.M.D. was supported by the Royal Geographical Society and the Royal Zoological Society of Scotland. B.W. was supported by the National Research Foundation of Korea (2015R1D1A1A01057282).Peer Reviewe
Temporary ponds: Adaptations and physiological constraints of the yellow-bellied toad (Bombina variegata) living in a habitat with an unpredictable risk of desiccation
Die Gelbbauchunke Bombina variegata gilt als eine typische Pionierart, die bevorzugt vegetationslose, ephemere GewĂ€sser mit hohem Austrocknungsrisiko als LaichgewĂ€sser nutzt. KleinstgewĂ€sser dieser Art zeichnen sich durch hohe Fluktuationen abiotischer (Temperatur, Ionenkonzentration, Wasserstand), aber auch biotischer Faktoren (Dichte, RĂ€uberdruck) aus. In Anpassung an das zeitlich und rĂ€umlich unvorhersehbare Auftreten dieser GewĂ€sser hat die Gelbbauchunke eine fĂŒr eine temperate Art auĂergewöhnlich lange Fortpflanzungsperiode (April - August). Die Weibchen zeigten wĂ€hrend der Saison eine kontinuierliche Eientwicklung, die es ihnen erlaubt, opportunistisch mehrfach abzulaichen und damit eine zeitliche Risikostreuung der Gelege zu betreiben. DarĂŒber hinaus nutzt Bombina variegata alle Möglichkeiten der rĂ€umlichen Risikostreuung, indem sie ihre Gelege in kleinen Portionen innerhalb von PfĂŒtzen, aber auch auf verschiedene PfĂŒtzen verteilt. Die hohe VariabilitĂ€t in den produzierten EigröĂen, besonders zwischen den Gelegen verschiedener Weibchen, lieĂ auf den ersten Blick eine weitere Strategie zur Risikostreuung vermuten; allerdings war die EigröĂe von der Kondition der Weibchen abhĂ€ngig: wĂ€hrend gut konditionierte Weibchen in der Lage waren, sowohl gröĂere Eier als auch gröĂere Gelege zu produzieren, gingen schlechter konditionierte Weibchen einen âtrade-offâ zugunsten einer möglichst hohen FekunditĂ€t ein. Unter gĂŒnstigen Bedingungen greift diese Strategie, wĂ€hrend die Produktion ĂŒberdurchschnittlich groĂer Eier unter Austrocknungsbedingungen von Vorteil ist: Kaulquappen groĂer Eier hatten eine entsprechend gröĂere SchlupfgröĂe und zeigten gegenĂŒber Quappen kleinerer Eier eine beschleunigte Entwicklung. Auch bei den Labor- und Freilanduntersuchungen, die sich mit der Frage be-schĂ€ftigten, wie Bombina variegata auf kritische VerĂ€nderungen des Wasservo-lumens reagiert, war eine enorme VariabilitĂ€t in den Wachstums- und EntwicklungsverlĂ€ufen der Kaulquappen der verschiedenen AnsĂ€tze zu beobachten, die sich nur bedingt auf abweichende Versuchsbedingungen zurĂŒckfĂŒhren lieĂ; vielmehr dĂŒrfte die qualitative Ausstattung der Quappen eine wesentliche Rolle gespielt haben. Dabei kristallisierten sich in den verschiedenen Versuchen zwei unterschiedliche Entwicklungsstrategien heraus: Kaulquappen, die eine insgesamt relativ lange Entwicklungszeit benötigten, zeigten eine hohe phĂ€notypische PlastizitĂ€t und reagierten adaptiv auf abnehmende WasserstĂ€nde, indem sie ihre Entwicklung auf Kosten ihres Wachstums beschleunigten. Bei Quappen, die im Durchschnitt eine wesentlich schnellere Entwicklungszeit besaĂen, war diese per se gĂŒnstige hohe Entwicklungsrate dagegen fixiert, unabhĂ€ngig davon, wĂ€hrend welcher Entwicklungsphase die Quappen auf verĂ€nderte Bedingungen umgestellt wurden. Unter verschlechterten Bedingungen zeigten sie lediglich WachstumseinbuĂen. Ăhnlich reagierten Kaulquappen auf zunehmende Ionenkonzentrationen bzw. sinkende WasserstĂ€nde. Dagegen wirkte sich Ammoniak, Exkretionsprodukt von Amphibienlarven, in erhöhten Konzentrationen stark negativ aus und beeintrĂ€chtigte sowohl das Wachstum als auch die Entwicklung der Quappen. Auf RĂ€uber, die im Vergleich zum Austrocknungsrisiko temporĂ€rer GewĂ€sser eine eher untergeordnete Rolle spielen, reagierten Bombina variegata-Quappen nur bedingt. Erst nach FĂŒtterung der Libellenlarven mit Unkenquappen schrĂ€nkten sie vorĂŒbergehend ihre AktivitĂ€t ein und mieden den rĂ€ubernahen Bereich, ohne dass dadurch die Entwicklungsgeschwindigkeit oder das Wachstum der Quappen beeintrĂ€chtigt wurde; allerdings war eine erhöhte MortalitĂ€t zu beobachten.The yellow-bellied toad, Bombina variegata, lives in highly dynamic habitats, where she predominantly uses shallow pools with no vegetation as breeding sites. These temporary ponds have a high risk of desiccation and show strong fluctuations in abiotic (e.g. temperature, ion concentration, water level) as well as biotic factors (e.g. density, predation pressure). In accordance with the unpredictability of breeding sites in time and space, Bombina variegata has an unusually long breeding season for a temperate zone species lasting from April to August. During this period females showed continuous egg development, allowing for repeated opportunistic spawning bouts as a temporal risk spreading strategy. Besides, B. variegata uses all opportunities of spacial risk spreading by distributing her eggs within as well as between different pools. A high variability of egg sizes, especially between clutches of different females was observed indicating another risk spreading strategy. However, mean egg size was dependent on the condition of the female: while females with an above average condition were able to produce both, large eggs as well as large clutches, females of lower condition were forced to undergo a trade-off, aiming at a high fecundity but at the cost of reduced egg size. This is a successful strategy under favourable conditions, however under drying conditions the pro-duction of large eggs is of major advantage: tadpoles from large eggs had larger hatching sizes and metamorphosed earlier than tadpoles from small eggs. Furthermore, an enormous variability in mean size at metamorphosis and devel-opmental time was observed in a series of lab and field experiments where tad-poles were exposed to varying water volumes. These findings cannot fully be attributed to differences in experimental design, but rather indicate inherent differences of tadpoles of different cohorts. Basically, two developmental strategies were observed: tadpoles exhibiting a long larval period had a high phenotypic plasticity and showed an adaptive trade-off under decreasing water levels, ac-celerating their development at the cost of reduced growth. On the other hand, tadpoles that developed at a faster rate in the first place showed a fixed devel-opment and merely reduced their growth, no matter at which developmental stage the change to unfavourable conditions occurred. Similar results were ob-tained when tadpoles were exposed to increases in ion concentrations or to wa-ter level reductions. However, increased levels of ammonia, the excretion prod-uct of tadpoles, led to a major negative impact on both, growth and development of the tadpoles. In comparison to the risk of desiccation, predators play only a minor role in temporary ponds. Accordingly, Bombina variegata tadpoles reduced their activity and avoided the area of the dragonfly larvae only temporarily, after these were fed with tadpoles. Neither growth nor development of the larvae were impaired; however, a higher mortality was observed
Statistical modeling of phenology in Bavaria based on past and future meteorological information
Plant phenology is well known to be affected by meteorology. Observed changes in the occurrence of phenological phases arecommonly considered some of the most obvious effects of climate change. However, current climate models lack a representationof vegetation suitable for studying future changes in phenology itself. This study presents a statistical-dynamical modelingapproach for Bavaria in southern Germany, using over 13,000 paired samples of phenological and meteorological data foranalyses and climate change scenarios provided by a state-of-the-art regional climate model (RCM). Anomalies of severalmeteorological variables were used as predictors and phenological anomalies of the flowering date of the test plantForsythiasuspensaas predictand. Several cross-validated prediction models using various numbers and differently constructed predictorswere developed, compared, and evaluated via bootstrapping. As our approach needs a small set of meteorological observationsper phenological station, it allows for reliable parameter estimation and an easy transfer to other regions. The most robust andsuccessful model comprises predictors based on mean temperature, precipitation, wind velocity, and snow depth. Its averagecoefficient of determination and root mean square error (RMSE) per station are 60% and ± 8.6 days, respectively. However, theprediction error strongly differs among stations. When transferred to other indicator plants, this method achieves a comparablelevel of predictive accuracy. Its application to two climate change scenarios reveals distinct changes for various plants andregions. The flowering date is simulated to occur between 5 and 25 days earlier at the end of the twenty-first century comparedto the phenology of the reference period (1961â1990)
Amphibians as indicators of changes in aquatic and terrestrial ecosystems following GM crop cultivation: a monitoring guideline
Amphibians are a suitable indicator group for monitoring possible negative direct or indirect effects of GMO cultivation at the individual and population level. Direct effects could occur in aquatic ecosystems via uptake of GM pollen or GM detritus by anuran larvae. However, indirect negative effects caused by changes in cultivation practices (changes in pesticide use, for instance) are more likely. The VDI Guideline 4333 aims to ensure comprehensive monitoring of the different life-stages of anuran species that are common in agricultural landscapes of Austria, Germany and Switzerland. The guideline includes a novel approach to tadpole monitoring. To assess immediate effects, tadpole, metamorph and adult deformation rates are compared with naturally occurring deformation rates. Adult population size, adult body condition and juvenile emergence are monitored over multiple years to assess long-term effects of GM crop cultivation on population viability. At each study site, monitoring has to be carried out at multiple amphibian breeding sites which differ in their exposure to GM crop cultivation. All monitoring data have to be stored in a central database for future meta-analyses. This will ultimately allow for generalized statements about the impact of GM crop cultivation on amphibians. Although specifically designed for GM crops, VDI Guideline 4333 may also serve as a model for studying the effects of a wider range of stressors on amphibian populations in agriculture and forestry