Microscopic Aquatic Predators Strongly Affect Infection Dynamics of a Globally Emerged Pathogen

Research on emerging infectious wildlife diseases has placed particular emphasis on host-derived barriers to infection and disease. This focus neglects important extrinsic determinants of the host/pathogen dynamic, where all barriers to infection should be considered when ascertaining the determinants of infectivity and pathogenicity of wildlife pathogens [1–3]. Those pathogens with free-living stages, such as fungi causing catastrophic wildlife declines on a global scale [4], must confront lengthy exposure to environmental barriers before contact with an uninfected host [5–8]. Hostile environmental conditions therefore have the ability to decrease the density of infectious particles, reducing the force of infection and ameliorating the impact as well as the probability of establishing an infection [9]. Here we show that, in nature, the risk of infection and infectious burden of amphibians infected by the chytrid fungus Batrachochytrium dendrobatidis (Bd) have a significant, site-specific component, and that these correlate with the microfauna present at a site. Experimental infections show that aquatic microfauna can rapidly lower the abundance and density of infectious stages by consuming Bd zoospores, resulting in a significantly reduced probability of infection in anuran tadpoles. Our findings offer new perspectives for explaining the divergent impacts of Bd infection in amphibian assemblages and contribute to our understanding of ecosystem resilience to colonization by novel pathogens

People, pollution and pathogens – Global change impacts in mountain freshwater ecosystems

Mountain catchments provide for the livelihood of more than half of humankind, and have become a key destination for tourist and recreation activities globally. Mountain ecosystems are generally considered to be less complex and less species diverse due to the harsh environmental conditions. As such, they are also more sensitive to the various impacts of the Anthropocene. For this reason,mountain regions may serve as sentinels of change and provide ideal ecosystems for studying climate and global change impacts on biodiversity. We here review different facets of anthropogenic impacts on mountain freshwater ecosystems. We put particular focus on micropollutants and their distribution and redistribution due to hydrological extremes, their direct influence on water quality and their indirect influence on ecosystem health via changes of freshwater species and their interactions. We show that those changes may drive pathogen establishment in new environments with harmful consequences for freshwater species, but also for the human population. Based on the reviewed literature, we recommend reconstructing the recent past of anthropogenic impact through sediment analyses, to focus efforts on small, but highly productive waterbodies, and to collect data on the occurrence and variability of microorganisms, biofilms, plankton species and key species, such as amphibians due to their bioindicator value for ecosystem health and water quality. The newly gained knowledge can then be used to develop a comprehensive framework of indicators to robustly inform policy and decision making on current and future risks for ecosystem health and human well-being

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 János 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 Ciência e a Tecnologia. L.F.T., C.L., L.P.R. K.R.Z., T.Y.J., T.S.J. were supported by São Paulo Research Foundation (FAPESP #2016/25358-3), the National Counsel of Technological and Scientific Development (CNPq #300896/2016–6) 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

Sélection sexuelle et honnêteté des signaux chez le Paon bleu (Pavo cristatus)

Les mâles de nombreuses espèces présentent un ensemble de caractères sexuels secondaires extravagants qui auraient évolués sous l action de la sélection sexuelle. Ces traits multiples pourraient signaler de manière fiable (i.e. honnête ) la qualité génétique des mâles. En préférant des mâles capables d exprimer les signaux les plus importants, les femelles pourraient bénéficier de la qualité génétique de leurs partenaires afin de la transmettre à leurs descendants. En retour, les femelles devraient investir d avantage dans la reproduction lorsqu elles sont appariées avec les mâles les plus attractifs. Nous avons étudié les mécanismes de la sélection sexuelle chez une espèce à lek, le Paon bleu, Pavo cristatus. Nous avons trouvé que les mâles développaient des signaux multiples. En effet, la compétition entre les mâles favorisait les mâles avec un long tarse et une longue traîne, et les femelles choisissaient les mâles en fonction de leur degré d ornementation et de leur activité de parade. Ces mâles installaient leur territoire là où la probabilité de rencontrer des femelles était la plus importante. Les signaux utilisés par les femelles pour choisir leurs partenaires se sont révélé être des témoins honnêtes de l état de santé des mâles et de leurs capacités immunitaires. Lorsqu elles étaient expérimentalement appariées avec des mâles attractifs, les femelles investissaient d avantage dans la reproduction. L ensemble de ces résultats démontre que les traits multiples des mâles ont pu évoluer car ils sont liés à des bons gènes que les femelles obtiennent pour leurs descendantsIn many species males exhibit varous conspicous secondary sexual traits thought to have evolved under sexual selection. These multiple traits may honestly signal male genetic quality. Prefering males able to express the most important signals, females may benefit from the genetic quality of their mates to transmit this genetic quality to their offspring. In turn, females are expected to invest more into reproduction when they are paired with more attractive males. We studied the mechanisms of sexual selection in a lekkig species, the Common peafowl, Pavo cristatus. We found that males display multiple signals. Indeed, male-male competition favored males with longer tarsis and longer trains and females preferred to mate with more ornamented males and males showing a high display rate. These males settled their territory where the probability to encounter females was the highest. The signals used by the femelles to choose a mate were honest signals of male health status and male immune capacities. When experiementally paired with attractive males, females invested more into reproduction. Overall, these results demonstrate that male multiple traits can have evolved because they were linked to good genes gathered by the females for their offspringPARIS-Museum Hist.Naturelle (751052304) / SudocSudocFranceF

Entre étalement et densification : une approche fine de l’urbanisation littorale sur la Côte bleue, Provence

International audienc

Mate-choice copying in Drosophila melanogaster: Impact of demonstration conditions and male–male competition

International audienceIndividuals of many species, including invertebrates, have been shown to use social information in mate choice, notably by extracting information from the mating performance of opposite sex conspecifics, a process called “mate-choice copying” (MCC). Here, we performed four experiments with Drosophila melanogaster to investigate two aspects of MCC methodology: whether providing positive and negative social information simultaneously or sequentially during the demonstration phase of the protocol, and male–male competition during the mate-choice test, affect MCC. We found that the simultaneous provision of positive and negative information during demonstrations hampered female MCC performance, compared to the sequential provision of information. This can be interpreted in two alternative, yet not exclusive, ways: attentional mechanisms may restrict the focus of the brain to one source of information at a time, and/or the shorter duration of demonstrations in the simultaneous protocol may have not permit full social learning use and may explain the non-detection of MCC in that protocol. Moreover, we did not detect any significant effect of male–male competition on female choice. This study thus provides further evidence for MCC in D. melanogaster and expands on the necessary methodology for detailed studies