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Dynamics of an emerging disease drive large-scale amphibian population extinctions / Vance T. Vredenburg in Proceedings of the National Academy of Sciences of the United States of America, 107 (21) (May 2010) 

Public Citation [article]  inProceedings of the National Academy of Sciences of the United States of America > 107 (21) (May 2010) . - 9689-9694 Titre : Dynamics of an emerging disease drive large-scale amphibian population extinctions Type de document : Imprimé Auteurs : Vance T. Vredenburg ; Roland A. Knapp ; Tate S. Tunstall ; Cheryl J. Briggs (1963-) Année de publication : 2010 Article en page(s) : 9689-9694 Langues : Anglais (eng) Catégories : [CBNPMP-Thématique] Enjeux de conservation des lacs d'altitude [CBNPMP-Thématique] Amphibiens Résumé : Epidemiological theory generally suggests that pathogens will not cause host extinctions because the pathogen should fade out when the host population is driven below some threshold density. An emerging infectious disease, chytridiomycosis, caused by the fungal pathogen Batrachochytrium dendrobatidis (Bd) is directly linked to the recent extinction or serious decline of hundreds of amphibian species. Despite continued spread of this pathogen into uninfected areas, the dynamics of the host–pathogen interaction remain unknown. We use fine-scale spatiotemporal data to describe (i) the invasion and spread of Bd through three lake basins, each containing multiple populations of the mountain yellow-legged frog, and (ii) the accompanying host–pathogen dynamics. Despite intensive sampling, Bd was not detected on frogs in study basins until just before epidemics began. Following Bd arrival in a basin, the disease spread to neighboring populations at ≈700 m/yr in a wave-like pattern until all populations were infected. Within a population, infection prevalence rapidly reached 100% and infection intensity on individual frogs increased in parallel. Frog mass mortality began only when infection intensity reached a critical threshold and repeatedly led to extinction of populations. Our results indicate that the high growth rate and virulence of Bd allow the near-simultaneous infection and buildup of high infection intensities in all host individuals; subsequent host population crashes therefore occur before Bd is limited by density-dependent factors. Preventing infection intensities in host populations from reaching this threshold could provide an effective strategy to avoid the extinction of susceptible amphibian species in the wild. Lien pérenne : DOI : 10.1073/pnas.091411110 Permalink : https://biblio.cbnpmp.fr/index.php?lvl=notice_display&id=150912 Vredenburg, Vance T., Knapp, Roland A., Tunstall, Tate S., Briggs, Cheryl J. (1963-) 2010 Dynamics of an emerging disease drive large-scale amphibian population extinctions. Proceedings of the National Academy of Sciences of the United States of America, 107(21): 9689-9694.

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Non-native fish introductions and the decline of the mountain yellow-legged frog from within protected areas / Roland A. Knapp in Conservation Biology, 14 (2) (2000) 

Public Citation [article]  inConservation Biology > 14 (2) (2000) . - 428-438 Titre : Non-native fish introductions and the decline of the mountain yellow-legged frog from within protected areas Type de document : Imprimé Auteurs : Roland A. Knapp ; Kathleen R. Matthews Année de publication : 2000 Article en page(s) : 428-438 Langues : Anglais (eng) Catégories : [CBNPMP-Thématique] Enjeux de conservation des lacs d'altitude [CBNPMP-Thématique] Poisson Résumé : One of the most puzzling aspects of the worldwide decline of amphibians is their disappearance from within protected areas. Because these areas are ostensibly undisturbed, habitat alterations are generally perceived as unlikely causes. The introduction of non-native fishes into protected areas, however, is a common practice throughout the world and may exert an important influence on amphibian distributions. We quantified the role of introduced fishes (several species of trout) in the decline of the mountain yellow-legged-frog (Rana muscosa) in California’s Sierra Nevada through surveys of >1700 sites in two adjacent and historically fishless protected areas that differed primarily in the distribution of introduced fish. Negat ive effects of fishes on the distri bution of frogs we re evident at three spatial scales. At the l a n d s c ape scale, c o m p a risons between The two protected areas indicated that fish distri bution was stro n g ly n egat ive ly corre l at e d with the distribution of frogs. At the watershed scale, the percentage of total water-body surface area occupied by fishes was a highly significant predictor of the percentage of total water-body surface area occupied by frogs. At the scale (if individual water bodies, frogs were three times more likely to be found and six times more abundant in fishless than in fish-containing water bodies, after habitat effects were accounted for. The strong effect of introduced fishes on mountain yellow-legged frogs appears to result from the unique life history of this amphibian which frequently restricts larvae to deeper water bodies, the same habitats into which fishes have most frequently been introduced. Because fish populations in at least some Sierra Nevada lakes can be removed with minimal effort, our results suggest that the decline of the mountain yellow-legged frog might be relatively easy to reverse. Permalink : https://biblio.cbnpmp.fr/index.php?lvl=notice_display&id=150994 Knapp, Roland A., Matthews, Kathleen R. 2000 Non-native fish introductions and the decline of the mountain yellow-legged frog from within protected areas. Conservation Biology, 14(2): 428-438.

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Consultable Article (2000) URL