Elevational and local climate variability predicts thermal breadth of mountain tropical tadpoles

The climate variability hypothesis posits that increased environmental thermal variation should select for thermal generalists, while stable environments should favor thermal specialists. This hypothesis has been tested on large spatial scales, such as latitude and elevation, but less so on smaller scales reflective of the experienced microclimate. Here, we estimated thermal tolerance limits of 75 species of amphibian tadpoles from an aseasonal tropical mountain range of the Ecuadorian Andes, distributed along a 3500 m elevational range, to test the climatic variability hypothesis at a large (elevation) and a small (microhabitat) scale. We show how species from less variable thermal habitats, such as lowlands and those restricted to streams, exhibit narrower thermal tolerance breadths than highland and pond-dwelling species respectively. Interestingly, while broader thermal tolerance breadths at large scales are driven by higher cold tolerance variation (heat-invariant hypothesis), at local scales they are driven by higher heat tolerance variation. This contrasting pattern may result from divergent selection on both thermal limits to face environmental thermal extremes at different scales. Specifically, within the same elevational window, exposure to extreme maximum temperatures could be avoided through habitat shifts from temporary ponds to permanent ponds or streams, while minimum peak temperatures remained invariable between habitats but steadily decreased with elevation. Therefore an understanding of the effects of habitat conversion is crucial for future research on resilience to climate change

Disease reservoirs threaten the recently rediscovered Podocarpus Stubfoot Toad (Atelopus podocarpus)

The Andes have experienced an unprecedented wave of amphibian declines and extinctions that are linked to a combination of habitat reduction and the spread of the fungal pathogen, Batrachochytrium dendrobatidis (Bd). In the present study, a range of high-altitude habitats in Southern Ecuador were surveyed for the presence of Bd. With a particular focus on Yacuri National Park, infection data are presented from across the resident amphibian community. This community contains a once putatively extinct species which was rediscovered in 2016, the Podocarpus Stubfoot Toad (Atelopus podocarpus). Across species, local Bd prevalence was 73% in tadpoles (n = 41 individuals from three species) and 14% in adults (n = 43 individuals from 14 species). Strikingly, 93% (14/15) of tested tadpoles of the recently described local endemic, Gastrotheca yacuri, were infected with a high pathogen load, suggesting that this species likely acts as a reservoir of infection in Yacuri. These findings show that the threat of disease for A. podocarpus still exists, and that this species requires urgent action to ensure its survival

Diseño de una campaña de educación para la salud en la población de Yurag.

El poderío de un país moderno se basa fundamentalmente en la investigación científica y el verdadero capital científico y técnico, está dado por la calidad de sus hombres de ciencia y por la intensidad de su trabajo. Pero, también la enseñanza universitaria no es una simple trasmisión de conocimientos adquiridos sino que debe preparar a sus alumnos para la vida profesional, emprendedora, creadora, con iniciativa, curiosidad investigativa, de juicio correcto, de aprendizaje diario, capaces de plantear problemas nuevos y de resolverlos adecuadamente

Data from: Elevational and microclimatic drivers of thermal tolerance in Andean Pristimantis frogs

Aim: We analysed elevational and microclimatic drivers of thermal tolerance diversity in a tropical mountain frog clade to test three macrophysiological predictions: less spatial variation in upper than lower thermal limits (Bretts’ heat invariant hypothesis); narrower thermal tolerance ranges in habitats with less variation in temperature (Janzen´s climatic variability hypothesis); and higher level of heat impacts at lower altitudes. Location: Forest and open habitats through a 4230 m elevational gradient across the tropical Andes of Ecuador. Method: We examined variability in critical thermal limits (CTmax, and CTmin), and thermal breadth (CTmax-CTmin) in 21 species of Pristimantis frogs. Additionally, we monitored maximum and minimum temperatures at the local-scale (tmax, tmin), and estimated vulnerability to acute thermal stress from heat (CTmax-tmax) and cold (tmin – CTmin), by partitioning thermal diversity into elevational and microclimatic variation. Results: Our results were consistent with Brett’s hypothesis: altitude promotes more variation in CTmin and tmin than in CTmax and tmax. Frogs inhabiting thermally variable open habitats have higher CTmax and tmax and greater thermal breadths than species restricted to forest habitats, which show less climatic overlap across the elevational gradient (Janzen´s hypothesis). Vulnerability to heat stress was higher in open than forest habitats and did not vary with altitude. Main conclusions: We suggest a mechanistic explanation of thermal tolerance diversity in elevational gradients by including microclimatic thermal variation. We propose that the unfeasibility to buffer minimum temperatures locally may explain the rapid increase in cold tolerance (lower CTmin) with elevation. In contrast, the relative invariability in heat tolerance (CTmax) with elevation may revolve around the organisms’ habitat selection of open and canopy buffered habitats. Secondly, on the basis of microclimatic estimates, lowland and upland species may be equally vulnerable to temperature increase, which is contrary to the pattern inferred from regional interpolated climate estimators

Datalogger information

Dataset with datalogger information from Pristimantis habitats and overlap analysi

Post‐epizootic microbiome associations across communities of neotropical amphibians

Microbiome–pathogen interactions are increasingly recognized as an important element of host immunity. While these host‐level interactions will have consequences for community disease dynamics, the factors which influence host microbiomes at larger scales are poorly understood. We here describe landscape‐scale pathogen–microbiome associations within the context of post‐epizootic amphibian chytridiomycosis, a disease caused by the panzootic chytrid fungus Batrachochytrium dendrobatidis. We undertook a survey of Neotropical amphibians across altitudinal gradients in Ecuador ~30 years following the observed amphibian declines and collected skin swab‐samples which were metabarcoded using both fungal (ITS‐2) and bacterial (r16S) amplicons. The data revealed marked variation in patterns of both B. dendrobatidis infection and microbiome structure that are associated with host life history. Stream breeding amphibians were most likely to be infected with B. dendrobatidis. This increased probability of infection was further associated with increased abundance and diversity of non‐Batrachochytrium chytrid fungi in the skin and environmental microbiome. We also show that increased alpha diversity and the relative abundance of fungi are lower in the skin microbiome of adult stream amphibians compared to adult pond‐breeding amphibians, an association not seen for bacteria. Finally, stream tadpoles exhibit lower proportions of predicted protective microbial taxa than pond tadpoles, suggesting reduced biotic resistance. Our analyses show that host breeding ecology strongly shapes pathogen–microbiome associations at a landscape scale, a trait that may influence resilience in the face of emerging infectious diseases

Engineering a future for amphibians under climate change

1.?Altered global climates in the 21st century pose serious threats for biological systems and practical actions are needed to mount a response for species at risk. 2.?We identify management actions from across the world and from diverse disciplines that are applicable to minimizing loss of amphibian biodiversity under climate change. Actions were grouped under three thematic areas of intervention: (i) installation of microclimate and microhabitat refuges; (ii) enhancement and restoration of breeding sites; and (iii) manipulation of hydroperiod or water levels at breeding sites. 3.?Synthesis and applications. There are currently few meaningful management actions that will tangibly impact the pervasive threat of climate change on amphibians. A host of potentially useful but poorly tested actions could be incorporated into local or regional management plans, programmes and activities for amphibians. Examples include: installation of irrigation sprayers to manipulate water potentials at breeding sites; retention or supplementation of natural and artificial shelters (e.g. logs, cover boards) to reduce desiccation and thermal stress; manipulation of canopy cover over ponds to reduce water temperature; and, creation of hydrologoically diverse wetland habitats capable of supporting larval development under variable rainfall regimes. We encourage researchers and managers to design, test and scale up new initiatives to respond to this emerging crisis