Infection patterns of the chytrid fungus, Batrachochytrium dendrobatidis, on anuran assemblages in agro-ecosystems from Buenos Aires Province, Argentina

Padrões de infecção do fungo quitrídeo, Batrachochytrium dendrobatidis, em assembleias de anuros de agro-ecossistemas da Província de Buenos Aires, Argentina. A quitridiomicose, causada pelo fungo quitrídeo patogênico Batrachochytrium dendrobatidis (Bd), está ligada a extinções e declínios de anfíbios. Adicionalmente, no contexto dos declínios de anfíbios, a perda de habitat relacionada às paisagens agrícolas é provavelmente a atividade humana isolada mais importante que afeta populações de anfíbios de planícies. Para avaliar o impacto do uso antropogênico da terra sobre a resposta dos anuros ao Bd, foram estudados os padrões de infecção em diversas lagoas de áreas cultivadas (CA) e incultas (UCA). Quatro espécies de anuros (Rhinella fernandezae [Bufonidae]; juvenis e adultos de Leptodactylus latrans [Leptodactylidae]; e os hilídeos Hypsiboas pulchellus e Pseudis minuta) foram monitoradas e amostras de tecido foram coletadas para diagnose e quantificação do Bd. Todas as espécies mostraram-se infectadas pelo Bd, mas os anuros de UCA tiveram probabilidade duas vezes maior de estar infectadas do que aquelas de CA. A prevalência e o nível de infecção foram significativamente maiores nas UCA, sugerindo que a vulnerabilidade ao Bd está associada ao uso da terra em agro-ecossistemas. No nível de assembleias, os padrões de infecção também diferiram entre as espécies, e aquelas de habitats aquáticos (L. latrans and P. minuta) tiveram alta prevalência e altos níveis de infecção de Bd. Os estágios juvenis de L. latrans tiveram maior prevalência e maior nível de infecção do que os adultos em ambas as áreas de estudo. Este trabalho contribui para o conhecimento dos efeitos antropogênicos sobre as relações hospedeiro-patógeno, particularmente sobre o efeito do Bd em assembleias de anuros sujeitas a diferentes níveis de impacto agrícola.Infection patterns of the chytrid fungus, Batrachochytrium dendrobatidis, on anuran assemblages in agro-ecosystems from Buenos Aires Province, Argentina. The disease chytridiomycosis, caused by the pathogenic chytrid fungus Batrachochytrium dendrobatidis (Bd), is linked to extinctions and declines of amphibians. Additionally, in the context of amphibian decline, the habitat loss related to agricultural landscapes is likely the single most important human activity affecting lowland amphibian populations. To assess the impact of anthropogenic land use on anuran response to Bd, infection patterns in several ponds from cultivated (CA) and uncultivated areas (UCA) were studied. Four anuran species (Rhinella fernandezae [Bufonidae]; juvenile and adult of Leptodactylus latrans [Leptodactylidae]; and the hylids Hypsiboas pulchellus and Pseudis minuta) were monitored and tissue samples were collected for Bd diagnosis and quantification. All species tested positive for Bd, but anurans inhabiting the UCA were twice more likely to be infected than those in the CA. Prevalence and infection level were significantly higher in the UCA, suggesting that vulnerability to Bd is associated with land use in agro-ecosystems. At the assemblage-level, the infection patterns also differed among species, and those with aquatic habitats (L. latrans and P. minuta) had high prevalence and infection levels of Bd. Juvenile stages of L. latrans had higher prevalence and infection level than adults in both study areas. This work contributes to our understanding of anthropogenic effects on host-pathogen relationships, particularly on the effect of Bd on anuran assemblages under different levels of agricultural impact

Genomic Correlates of Virulence Attenuation in the Deadly Amphibian Chytrid Fungus, Batrachochytrium dendrobatidis.

Emerging infectious diseasespose a significant threat to global health, but predicting disease outcomes for particular species can be complicated when pathogen virulence varies across space, time, or hosts. The pathogenic chytrid fungus Batrachochytrium dendrobatidis (Bd) has caused worldwide declines in frog populations. Not only do Bd isolates from wild populations vary in virulence, but virulence shifts can occur over short timescales when Bd is maintained in the laboratory. We leveraged changes in Bd virulence over multiple generations of passage to better understand mechanisms of pathogen virulence. We conducted whole-genome resequencing of two samples of the same Bd isolate, differing only in passage history, to identify genomic processes associated with virulence attenuation. The isolate with shorter passage history (and greater virulence) had greater chromosome copy numbers than the isolate maintained in culture for longer, suggesting that virulence attenuation may be associated with loss of chromosome copies. Our results suggest that genomic processes proposed as mechanisms for rapid evolution in Bd are correlated with virulence attenuation in laboratory culture within a single lineage of Bd. Moreover, these genomic processes can occur over extremely short timescales. On a practical level, our results underscore the importance of immediately cryo-archiving new Bd isolates and using fresh isolates, rather than samples cultured in the laboratory for long periods, for laboratory infection experiments. Finally, when attempting to predict disease outcomes for this ecologically important pathogen, it is critical to consider existing variation in virulence among isolates and the potential for shifts in virulence over short timescales

Pruebas para evaluar el entendimiento conceptual en cursos de zoología y botánica

How to cite: Nazario, G. M. & Burrowes, P. A. (2006). Pruebas para evaluar el entendimiento conceptual en cursos de zoología y botánica. Pedagogía, 39(1), 150-170.Cómo citar: Nazario, G. M. & Burrowes, P. A. (2006). Pruebas para evaluar el entendimiento conceptual en cursos de zoología y botánica. Pedagogía, 39(1), 150-170

Genetic analysis of post‐epizootic amphibian chytrid strains in Bolivia: Adding a piece to the puzzle

The evolutionary history and dispersal pattern of Batrachochytrium dendrobatidis (Bd), an emergent fungal pathogen responsible for the decline and extinctions of many species of amphibians worldwide, is still not well understood. In South America, the tropical Andes are known as an important site for amphibian diversification, but also for being a place where hosts are at greater risk of chytridiomycosis. In an attempt to understand the history and the geographic pattern of Bd‐associated amphibian declines in Bolivia, we isolated Bd from hosts at two locations that differ in their chronology of Bd prevalence and host survival outcome, the cloud forests of the Amazonian slopes of the Andes and Lake Titicaca in the altiplano. We genotyped Bd from both locations and sequenced the genome from the cloud forest isolate and then compared them to reference sequences of other Bd strains across the world. We found that the Bolivian chytrid isolates were nearly genotypically identical and that they belong to the global panzootic lineage (Bd‐GPL). The Bolivian Bd strain grouped with other tropical New World strains but was closest to those from the Brazilian Atlantic Forest. Our results extend the presence of Bd‐GPL to the central Andes in South America and report this hypervirulent strain at Lago Titicaca, where Bd has been detected since 1863, without evidence of amphibian declines. These findings suggest a more complex evolutionary history for this pathogen in Bolivia and may point to the existence of an old lineage of Bd that has since been extirpated following the arrival of the panzootic Bd‐GPL or that the timing of Bd‐GPL emergence is earlier than generally acknowledged.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/162756/2/tbed13568_am.pdfhttp://deepblue.lib.umich.edu/bitstream/2027.42/162756/1/tbed13568.pd

Response to comment on 'Amphibian fungal panzootic causes catastrophic and ongoing loss of biodiversity'

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

Disentangling host, pathogen, and environmental determinants of a recently emerged wildlife disease: lessons from the first 15 years of amphibian chytridiomycosis research

The amphibian fungal disease chytridiomycosis, which affects species across all continents, recently emerged as one of the greatest threats to biodiversity. Yet, many aspects of the basic biology and epidemiology of the pathogen, Batrachochytrium dendrobatidis (Bd), are still unknown, such as when and from where did Bd emerge and what is its true ecological niche? Here, we review the ecology and evolution of Bd in the Americas and highlight controversies that make this disease so enigmatic. We explore factors associated with variance in severity of epizootics focusing on the disease triangle of host susceptibility, pathogen virulence, and environment. Reevaluating the causes of the panzootic is timely given the wealth of data on Bd prevalence across hosts and communities and the recent discoveries suggesting co‐evolutionary potential of hosts and Bd. We generate a new species distribution model for Bd in the Americas based on over 30,000 records and suggest a novel future research agenda. Instead of focusing on pathogen “hot spots,” we need to identify pathogen “cold spots” so that we can better understand what limits the pathogen's distribution. Finally, we introduce the concept of “the Ghost of Epizootics Past” to discuss expected patterns in postepizootic host communities.We review the ecology and evolution of amphibian fungal disease chytridiomycosis in the Americas, where it has recently emerged as one of the greatest threats to biodiversity and highlight controversies that make this disease so enigmatic. We explore factors associated with variance in severity of epizootics focusing on the disease triangle of host susceptibility, pathogen virulence, and environment. We generate a new species distribution model for Bd in the Americas based on over 30,000 records, which suggests emphasis needs to be placed on studying pathogen “cold spots” so that we can better understand what biotic and abiotic factors limit the pathogen's distribution.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/113682/1/ece31672_am.pdfhttp://deepblue.lib.umich.edu/bitstream/2027.42/113682/2/ece31672.pd

Conserving the Puerto Rican herpetofauna

With a total area of 8900 km2, Puerto Rico is the smallest of the Greater Antilles. It is divided in three physiographic regions or areas of relief: the mountainous interior, the karst region, and the coastal plains and valleys. The island comprises six ecological life zones: subtropical dry forest, subtropical moist forest, subtropical wet forest, subtropical rain forest, lower montane wet forest and lower montane rain forest. The herpetofauna of Puerto Rico consists of 25 species of amphibians (19 native, six introduced) and 56 species of reptiles (52 native, four introduced). The goal of this paper is to describe some of the present studies directed towards the conservation of Puerto Rican herpetofauna. Eleutherodactylus karlschmidti, E. jasperi and E. eneidae have not been seen or heard since 1976, 1981 and 1990, respectively, and are probably extinct. Since 2000, the potential causes of amphibian declines in Puerto Rico have been studied, and a synergistic interaction between climate change (increased dry periods) and disease (chytridiomycosis) have been proposed as an explanation for the patterns observed. Recovery efforts for Peltophryne lemur include a captivebreeding program, reintroductions island-wide educational outreach, protection and restoration of existing habitat, and the creation of new breeding ponds. Among reptiles, the first conservation efforts to protect Epicrates inornatus were limited to trying to halt collection and hunting. However, current strategies to preserve the boa include gathering basic biological information, habitat conservation, and educational outreach. Recent efforts for the conservation of Trachemys s. stejnegeri combine three research approaches to clarify the status of local populations: a mark-recapture-release study, field monitoring of reproductive activity (i.e., nocturnal patrolling to identify nesting activity), and field assessment of the potential impact of introduced species, particularly identification of predatory species and exotic turtles. Recovery initiatives for Cyclura stejnegeri include management of invasive mammals, a headstart program for hatchling iguanas, and the assessment of the etiology of a condition causing blindness in adult iguanas. A reforestation project aimed at recovering a local herpetofaunal assemblage after disturbances in a limestone valley in northern Puerto Rico is discussed. As population sizes of common colonizers such as Eleutherodactylus and Anolis increased, larger forest-interior and predatory species like Epicrates inornatus, Alsophis portoricensis and Anolis cuvieri followed. Finally, the Mona Island marine turtle monitoring program is discussed and compared to other similar programs in Puerto Rico. As these and other similar conservation efforts provide scientifically based management recommendations, we hope to succeed in conserving the diverse herpetofauna that characterizes Puerto Rico

Use of micro CHP plants to support the local operation of electric heat pumps

Fig. 1. Global distribution of chytridiomycosis-associated amphibian species declines. Bar plots indicate the number (N) of declined species, grouped by continental area and classified by decline severity. Brazilian species are plotted separately from all other South American species (South America W); Mesoamerica includes Central America, Mexico, and the Caribbean Islands; and Oceania includes Australia and New Zealand. No declines have been reported in Asia. n, total number of declines by region. [Photo credits (clockwise from top left): Anaxyrus boreas, C. Brown, U.S. Geological Survey; Atelopus varius, B.G.; Salamandra salamandra, D. Descouens, Wikimedia Commons; Telmatobius sanborni, I.D.l.R; Cycloramphus boraceiensis, L.F.T.; Cardioglossa melanogaster, M.H.; and Pseudophryne corroboree, C. Doughty

La crisis mundial de los anfibios: otra historia de pandemias

Enlace de la retransmisión de la actividad: https://www.youtube.com/live/zUIeBo_MlM4?feature=shareDesde finales del siglo pasado los expertos empezaron a notar un declive drástico en las poblaciones de anfibios en casi todas partes del mundo. Un esfuerzo exhaustivo de averiguar las causas, documentó procesos antropogénicos (como deforestación o el cambio climático global) que afectaron a muchas especies, pero de manera mucho más alarmante, el efecto de un hongo patógeno que se dispersó por todo el mundo. En esta charla hablaremos de cómo sucedió todo esto, de las especies que perdimos y de cómo los científicos han descubierto patrones que nos ayudan a entender la vulnerabilidad de los animales a las enfermedades infecciosas emergentes.N