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The important hypothesis that organic livestock management reduces the prevalence of antimicrobial resistance is either fiercely supported or bitterly contested. Yet, empirical evidence supporting this view remains fragmentary, in part because relationships between antimicrobial use and drug resistance vary dramatically across contexts, hosts, pathogens, and country-specific regulations. Here, we synthesize global policies and definitions of ‘organic’ and ask if organic farming results in notable reductions in the prevalence of antimicrobial resistance when directly examined alongside conventional analogs. We synthesized the results of 72 studies, spanning 22 countries and five pathogens. Our results highlight substantial variations in country-specific policies on drug use and definitions of ‘organic’ that hinder broad-scale and generalizable patterns. Overall, conventional farms had slightly higher prevalence of antimicrobial resistance (28%) relative to organic counterparts (18%), although we found significant context-dependent variation in this pattern. Notably, environmental samples often exhibited high levels of resistance to medically important drugs, underscoring the need for more stringent and consistent policies to control antimicrobial contaminants in the soil. Taken together, these results emphasize the challenges inherent in understanding links between drug use and drug resistance and the critical need for global standards governing organic policies and greater investment in viable alternatives for managing disease in livestock., conventional and organic farms food borne pathogen

By altering the abundance, diversity, and distribution of species — and their pathogens — globalization may inadvertently select for more virulent pathogens. In Brazil’s Atlantic Forest, a hotspot of amphibian biodiversity, the pet trade has facilitated the co-occurrence of previously isolated enzootic and panzootic lineages of the pathogenic amphibian-chytrid (‘Bd’) and generated new virulent recombinant genotypes (‘hybrid’). Epidemiological data indicate that amphibian declines are most severe in hybrid zones, suggesting that coinfections are causing more severe infections or selecting for higher virulence. We investigated how coinfections involving these genotypes shaped virulence and transmission. Overall, coinfection favored the more virulent and competitively superior panzootic genotype, despite dampening its virulence and transmission. However, for the least virulent and least competitive genotype, coinfection increased both pathogen virulence and transmission. Thus, by integrating experimental and epidemiological data, our results provide mechanistic insight into how globalization can select for, and propel, the emergence of introduced hypervirulent lineages, such as the globally distributed panzootic lineage of Bd.

Made available in DSpace on 2021-06-25T12:20:15Z (GMT). No. of bitstreams: 0 Previous issue date: 2020-09-28 Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP) Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq) Royal Society Replicated bromeliad microecosystems were used to examine warming-induced community shifts and changes to tadpole gut microbiome. Tadpole growth was more strongly associated with cascading effects of warming on gut dysbiosis than with direct warming effects or indirect effects on food resources. Anthropogenic climate warming affects many biological systems, ranging in scale from microbiomes to biomes. In many animals, warming-related fitness depression appears more closely linked to changes in ecological community interactions than to direct thermal stress. This biotic community framework is commonly applied to warming studies at the scale of ecosystems but is rarely applied at the scale of microbiomes. Here, we used replicated bromeliad microecosystems to show warming effects on tadpole gut microbiome dysbiosis mediated through biotic community interactions. Warming shifted environmental bacteria and arthropod community composition, with linkages to changes in microbial recruitment that promoted dysbiosis and stunted tadpole growth. Tadpole growth was more strongly associated with cascading effects of warming on gut dysbiosis than with direct warming effects or indirect effects on food resources. These results suggest that assessing warming effects on animal health requires an ecological community perspective on microbiome structure and function. Univ Alabama, Dept Biol Sci, Tuscaloosa, AL USA Univ Estadual Paulista, Programa Posgrad Biol Anim, Sao Jose Do Rio Preto, Brazil Univ Estadual Paulista, Dept Biodivers, Rio Claro, Brazil Univ Estadual Paulista, Aquaculture Ctr CAUNESP, Rio Claro, Brazil Univ Estadual Campinas, Dept Biol Anim, Lab Hist Nat Anfibios Brasileiros LaHNAB, Campinas, Brazil Univ Estadual Campinas, Inst Biol, Programa Posgrad Ecol, Campinas, Brazil Univ Estadual Campinas, Dept Biol Anim, Campinas, Brazil Univ Estadual Paulista, Programa Posgrad Biol Anim, Sao Jose Do Rio Preto, Brazil Univ Estadual Paulista, Dept Biodivers, Rio Claro, Brazil Univ Estadual Paulista, Aquaculture Ctr CAUNESP, Rio Claro, Brazil FAPESP: 2017/26162-8 FAPESP: 2018/23622-0 FAPESP: 2016/25358-3 FAPESP: 2019/18335-5 FAPESP: 2013/50741-7 FAPESP: 2017/09052-4 FAPESP: 2018/12225-0 CNPq: 300896/2016-6 CNPq: 306623/2018-8 Royal Society: NAF\R2\180791

Amphibian skin bacteria may confer protection against the fungus Batrachochytrium dendrobatidis (Bd), but responses of skin bacteria to different Bd lineages are poorly understood. The global panzootic lineage (Bd-GPL) has caused amphibian declines and extinctions globally. However, other lineages are enzootic (Bd-Asia-2/Brazil). Increased contact rates between Bd-GPL and enzootic lineages via globalization pose unknown consequences for host-microbiome-pathogen dynamics. We conducted a laboratory experiment and used 16S rRNA amplicon-sequencing to assess: (i) whether two lineages (Bd-Asia-2/Brazil and Bd-GPL) and their recombinant, in single and mixed infections, differentially affect amphibian skin bacteria; (ii) and the changes associated with the transition to laboratory conditions. We determined no clear differences in bacterial diversity among Bd treatments, despite differences in infection intensity. However, we observed an additive effect of mixed infections on bacterial alpha diversity and a potentially antagonistic interaction between Bd genotypes. Additionally, observed changes in community composition suggest a higher ability of Bd-GPL to alter skin bacteria. Lastly, we observed a drastic reduction in bacterial diversity and a change in community structure in laboratory conditions. We provide evidence for complex interactions between Bd genotypes and amphibian skin bacteria during coinfections, and expand on the implications of experimental conditions in ecological studies.

Made available in DSpace on 2020-12-12T02:04:44Z (GMT). No. of bitstreams: 0 Previous issue date: 2020-05-01 Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP) Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq) Cool-adapted species inhabiting montane tropical forests are vulnerable to heat stress associated with climate warming. According to the thermal mismatch hypothesis, pathogens are predicted to have broader thermal tolerances than their hosts, which can lead to increased pathogen loads and host mortality when temperatures are outside hosts' thermal optima. We tested the thermal mismatch hypothesis in two habitat generalist species expected to have wide thermal tolerance ranges: Dendropsophus minutus captured at a high elevation and D. elegans captured at a warmer low elevation. We also tested high-elevation individuals of the Brazilian direct-developing species Ischnocnema parva, which are expected to have a narrow thermal tolerance range based on life history. We exposed all frogs to the pathogenic fungus Batrachochytrium dendrobatidis (Bd) under three temperatures ranging from the average nighttime temperature where frogs were collected (16 and 21 °C for high and low elevations, respectively) to a simulated warming event (26 °C). Bd loads across all three host species were negatively associated with temperature. However, the interaction between Bd infection and warming led to increased mortality in cool-adapted I. parva at higher temperatures, despite lower infection loads. Our results indicate that Bd may lead to declines of cool-adapted montane frogs under the combined pressures of pathogen infection and warming, even at temperatures approaching the pathogen's upper thermal limit. Thus, climatic warming at a level that lowers fitness of heat-sensitive pathogens may not uniformly reduce host disease risk. Department of Biological Sciences The University of Alabama Departamento de Biologia Animal Universidade Estadual de Campinas (UNICAMP) Centro de Ciências Biológicas e da Saúde Universidade Federal de São Carlos Department of Biology Texas State University Department of Biological Sciences University of Notre Dame Departamento de Zoologia Instituto de Biociências and Centro de Aquicultura (CAUNESP) Universidade Estadual Paulista (UNESP) Departamento de Zoologia Instituto de Biociências and Centro de Aquicultura (CAUNESP) Universidade Estadual Paulista (UNESP) FAPESP: 2013/50741-7 FAPESP: 2016/03344-0 FAPESP: 2016/25358-3 FAPESP: 2018/23622-0 CNPq: 300896/2016-6 CNPq: 306623/2018-8

Lambert et al . question our retrospective and holistic epidemiological assessment of the role of chytridiomycosis in amphibian declines. Their alternative assessment is narrow and provides an incomplete evaluation of evidence. Adopting this approach limits understanding of infectious disease impacts and hampers conservation efforts. We reaffirm that our study provides unambiguous evidence that chytridiomycosis has affected at least 501 amphibian species.

The demise of amphibians? Rapid spread of disease is a hazard in our interconnected world. The chytrid fungus Batrachochytrium dendrobatidis was identified in amphibian populations about 20 years ago and has caused death and species extinction at a global scale. Scheele et al. found that the fungus has caused declines in amphibian populations everywhere except at its origin in Asia (see the Perspective by Greenberg and Palen). A majority of species and populations are still experiencing decline, but there is evidence of limited recovery in some species. The analysis also suggests some conditions that predict resilience. Science , this issue p. 1459 ; see also p. 1386

List of collections; Tables S1-S6; Figures S1-S3

The chytrid fungus Batrachochytrium dendrobatidis (Bd) has been linked to the declines of more than 500 amphibian species globally. In Brazil, Bd has been identified in several regions but predominantly in the Atlantic Forest. Data on the occurrence of this amphibian pathogen in northeastern Brazil are scarce, specifically from the Caatinga ecoregion, where there is only one study that reports Bd in the region. This study is the first to show a high prevalence of Bd in Caatinga’s species and includes two new records of species infected by Bd: Rhinella granulosa and R. jimi. In addition, we discuss the possibility of amphibian with terrestrial habits serving as potential Bd reservoirs in semiarid climate regions.

The recent increase in emerging fungal diseases is causing unprecedented threats to biodiversity. The origin of spread of the frog-killing fungus Batrachochytrium dendrobatidis ( Bd ) is a matter of continued debate. To date, the historical amphibian declines in Brazil could not be attributed to chytridiomycosis; the high diversity of hosts coupled with the presence of several Bd lineages predating the reported declines raised the hypothesis that a hypervirulent Bd genotype spread from Brazil to other continents causing the recent global amphibian crisis. We tested for a spatio-temporal overlap between Bd and areas of historical amphibian population declines and extinctions in Brazil. A spatio-temporal convergence between Bd and declines would support the hypothesis that Brazilian amphibians were not adapted to Bd prior to the reported declines, thus weakening the hypothesis that Brazil was the global origin of Bd emergence. Alternatively, a lack of spatio-temporal association between Bd and frog declines would indicate an evolution of host resistance in Brazilian frogs predating Bd 's global emergence , further supporting Brazil as the potential origin of the Bd panzootic. Here, we Bd -screened over 30 000 museum-preserved tadpoles collected in Brazil between 1930 and 2015 and overlaid spatio-temporal Bd data with areas of historical amphibian declines. We detected an increase in the proportion of Bd -infected tadpoles during the peak of amphibian declines (1979–1987). We also found that clusters of Bd -positive samples spatio-temporally overlapped with most records of amphibian declines in Brazil's Atlantic Forest. Our findings indicate that Brazil is post epizootic for chytridiomycosis and provide another piece to the puzzle to explain the origin of Bd globally.