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Tadpole tolerance Could you expand on the importance of understanding and predicting the vulnerability of animal populations to climate change? Assessing the impacts of climate change in amphibians and other organisms will require an integrative approach that assesses the sensitivity of organisms – for instance by measuring their thermal resistances – and combines these data with environmental information that evaluates their exposure to climate changes at regional, local and microenvironmental levels. This bigger picture of sensitivity and exposure will be essential for identifying which species and ecosystems are most vulnerable, and thus prioritising them in management programmes. To begin, can you discuss the primary focus of your research group on evolutionary biology? The project has a number of international collaborators. Can you outline the benefits of cooperating at a global level? The group I am leading is mainly concerned with the adaptive response of amphibians to stressful environmental conditions, especially during their aquatic larval stage. We have previously conducted research to identify local adaptations and the role of phenotypic plasticity as a potential mechanism of adaptation to stressful environments, such as drying ponds, salinity and other pollutants. At present, we are concerned with analysing the thermal adaptations of amphibians living in contrasting thermal environments and providing a mechanistically-based assessment of amphibian tadpoles’ vulnerabilities to heating stress in the coming decades at the population, species and community levels. Amphibians, and most ectothermic biodiversity, are concentrated in the tropics. Especially rich are Neotropical realms, where 50 per cent of all recognised amphibian species live. Our collaborations with local South American herpetologists in Argentina, Brazil, Ecuador and Colombia allow the examination of vulnerabilities from different Neotropical biomes, such as tropical mountain forest, high páramos, tropical and subtropical savannahs, and dry forests. This is fundamental to providing a comprehensive risk assessment of the impressive frog diversity. How did the focus on amphibian risk of heating stress arise? This project emerged by serendipity in 2006, during a field trip through the Gran Chaco with my colleague Federico Marangoni. We were astonished to find water temperatures exceeding 41 °C in ponds that swarmed with hundreds of tadpoles. How could these species face such extreme thermal conditions? And more pressingly, how would they face the likely increase in thermal stress in the coming decades? This led me to think that heating damage could be a potential source of amphibian population decline and species extirpation (localised extinction) in the future. species may be fundamental when designing the architecture, location and surrounding habitats of these ponds, in order to recreate optimal thermal pond microenvironments. DR MIGUEL TEJEDO Amphibians living in tropical and subtropical climes face a host of challenges to their survival. Here, Dr Miguel Tejedo explains how future changes in the Earth’s climate may further increase this pressure The analysis of species thermal sensitivity requires standardised methods in the experimental assays that are conducted in remote field sites. We have developed self-made portable instruments that are receiving patent licensing in a joint technological transfer with LorEnergía, Ltd. Are effective strategies to protect at-risk amphibians and other animals being developed? Could you discuss the challenges to their implementation? Unfortunately, it appears that mitigating strategies at the global or even regional scale will not prove viable. The only realistic strategy will be a reduction of global greenhouse gas emissions. Optimistically, some capacity to ameliorate impacts could be developed at the local level by imaginative management actions to both reduce exposure and increase resilience of the most endangered species or ecosystems. Collaborators in temperate areas, like the US, are also crucial for clarifying whether coldadapted species from higher latitudes are also vulnerable to heat impacts. We predict that, in other frog communities under similar climatic conditions from other continents, we may find a similar pattern of warming tolerances as those obtained in the studied temperate and tropical communities, but this will require further research. Do you have partnerships outside of the research community? What are the benefits of this cooperation? Aside from academic forums, we also collaborate with species conservation agencies to help with compensatory actions, such as construction programmes for new ponds to potentiate amphibian populations. A precise knowledge of thermal sensitivity of target endangered WWW.RESEARCHMEDIA.EU 71 DR MIGUEL TEJEDO Tropical survival With the future of the world’s tropical and subtropical amphibians at risk, evolutionary ecologists at the Doñana Biological Station in Seville are using a novel metric to enable precise predictions on the biological consequences of climate change DURING THE 20TH CENTURY, the Earth’s temperature rose by 0.6 °C, a rate of warming that has resulted in rapid environmental changes. According to the Intergovernmental Panel on Climate Change (IPCC), it is likely that the current rate will increase fivefold before the end of this century. The effects of rising temperatures can be seen most strikingly in the shifting landscape at the planet’s poles but the predicted increase in warming will have visible consequences for ecosystems in the Earth’s more habitable regions. Representing 80-90 per cent of the world’s amphibious fauna, tropical and subtropical The brazilian frog Phyllodytes luteolus in a water body inside a bromeliad. Amphibians can breed in aquatic environments of reduced dimensions and these microenvironments suffer very extreme temperatures. © Miguel Tejedo amphibians are already the most endangered vertebrates due to a host of anthropogenic factors such as the destruction of natural habitats, pollution and the emergence of infectious diseases. Climate change can be added to the already extensive list of risk factors threatening their existence as concerns arise over the likelihood that rates of warming will outpace their evolutionary adaptation. As ecosystems change, it is vital to identify which species and communities are most in danger of extinction, in order to make accurate predictions of the biological consequences of global warming. EVOLUTIONARY ECOLOGY AND CONSERVATION Belonging to the Spanish Council for Scientific Research (CSIC), the Doñana Biological Station in Seville is dedicated to uncovering the mechanisms that underpin biodiversity, how it is sustained and what leads to its decline. Dr Miguel Tejedo is an assistant professor of research at the Department of Evolutionary Ecology. Using macrophysiology (the evolution of large-scale physiological variation) and comparative phylogenetic approaches, the group study the evolution of thermal adaptations of amphibians living in contrasting thermal environments, including tropical, subtropical and temperate communities through Europe and North and South America. Field work with Tejedo and colleagues at the Caatinga reserve of Contendas do Sincorá, Bahia, Brazil. © Miguel Tejedo Such a broad geographical range of field studies means collaboration with local scientific research institutions is vital. With funding from Spain’s Ministry of Economy and Competitiveness (MINECO) and the Spanish Agency for International Cooperation for Development (AECID), Tejedo’s research focuses on a global risk assessment of warming-induced stress on amphibians, in order to determine which communities are more susceptible to suffer population decline and species extirpation in the near future. Amphibians are most vulnerable to heat stresses when they are still aquatic tadpoles. This is because water not only has a high heat capacity but is also an excellent conductor, meaning a warm pond is likely to be uniform in its heat distribution with no sanctuary of cooler microhabitats. Regarding the position these tadpoles may face, Tejedo is unequivocal: “In this limiting situation, they must have the ability to withstand heating or else they will die”. In order to make precise predictions about their fate, Tejedo hopes to perform a physiological assessment of their vulnerability and identify the most at-risk communities and species. WARMING TOLERANCE METRICS Based on the available data describing tadpole critical thermal limits, it is predicted that amphibians residing in tropical and subtropical climes may face the highest risk of extinction as a result of global warming. In low-latitude regions ‘cold-blooded’ ectotherms, such as tadpoles, live in environments that are more similar to their optimal temperature than those living at highlatitudes. As upper thermal limits are not coupled with geographic location, tadpoles in low-latitude, tropical and subtropical regions are subject to environmental temperatures much closer to their upper thresholds. To make possible the delivery of an integrative framework that evaluates amphibian vulnerability, Tejedo needs data regarding species’ sensitivity to heat stress and their exposure to changes in the climate. Previous efforts to establish such a framework have focused on the current distributional range of climatic parameters to produce estimations of ectothermal sensitivity to heat stress, but this methodology has its limitations. Professor Mirco Solé and his team conducting field work at the Mata Atlantica reserve of Serra Bonita, Bahia, Brazil. © Miguel Tejedo 72INTERNATIONAL INNOVATION Without taking into account the circumstances of a species’ biogeographical history it is difficult to produce estimates with real meaning. INTELLIGENCE VULNERABILITY OF AMPHIBIANS TO WARMING OBJECTIVES To provide a physiologically-based assessment of amphibian risk of heating stress due to global warming and identify the most vulnerable of the world’s biomes and amphibian communities to possible loss of population and species. KEY COLLABORATORS Juan F Beltrán, Universidad de Sevilla, Spain • Manuel Hernando Bernal, Universidad del Tolima, Colombia • Federico Marangoni, Instituto de Biología Subtropical (IBS; FCEQyNUNaM; CONICET), Argentina • Andrés MerinoViteri; Santiago Ron, Pontificia Universidad Católica de Ecuador • Carlos A Navas, Instituto de Biociências, Universidade de São Paulo, Brazil • Alfredo G Nicieza, Universidad de Oviedo, Spain • Rick A Relyea, University of Pittsburgh, USA • Mirco Solé; Andrés Egea, Universidade Estadual de Santa Cruz, Brazil • Enrique MartinLorente, LorEnergía, Ltd, Spain FUNDING Ministry of Economy and Competitiveness (MINECO) – award no. CGL2012-40246-C02-01 (2013-2015) • Spanish Agency for International Cooperation for Development (AECID) – award no. A/016892/08, A/023032/09 and AP/038788/11 Waxy monkey frog Phyllomedusa sauvagii from the subtropical Gran Chaco region of Argentina. © Miguel Tejedo Hampering this approach further is the almost total lack of micro-environmental climatic variation analysis in available literature. However, by establishing physiological assays and monitoring microenvironmental temperatures, Tejedo has arrived at the warming tolerance metric, a simple measure that describes the difference between the maximum temperature tolerated by an organism and the maximum microenvironmental temperature it experiences, or will do in the future. Crucially, special attention has been paid to the IPCC’s predicted increase in the rate of warming. With this metric it is possible to derive data on the susceptibility to heat stress of a particular species, population or community. “The range of tolerances obtained will describe the level of vulnerability at present and in the coming decades,” states Tejedo. COPING WITH STRESS Consistent with their predictions, the group’s physiological assays show that tropical and subtropical, low-latitude communities, are generally the most vulnerable to the dangers of heat stress, with some exceptions of lowtolerance communities in temperate climes. Their ability to survive the future rise in temperatures is hampered considerably by low levels of migratory dispersal and their inability to adapt fast enough to environmental changes. Although their phenotypic plasticity means that acclimatisation is a tadpole’s best bet, they may only be able to cope with a maximum increase of 1-3 °C. Unlike temperate communities, however, Tejedo has found that most subtropical species exhibit a potential for short-term acclimatisation where a quick increase in their thermo-tolerance can alleviate specific episodes of heat shock such as heat waves – a useful strategy for protection during the larval CONTACT Tropical and subtropical amphibians are the world’s most endangered vertebrates stage that could be essential to their survival beyond the end of the century. Within the tropical and subtropical category there exists a divide between amphibians breeding in ponds open to the elements and those breeding in forested habitats, where the natural canopy provides shelter from dangerous peak temperatures. Though seemingly living a more assured existence, the tadpoles with protective cover actually have a much lower thermal resistance than their open forest-dwelling cousins. As Tejedo explains, for these covered communities, deforestation can have dire consequences: “If the protective umbrella disappears, these species will become highly vulnerable”. Dr Miguel Tejedo Assistant Professor of Research Estación Biólogica de Doñana Spanish Council for Scientific Research (CSIC) 41092 Sevilla, Spain T + 34 629 58 10 51 E [email protected] www.ebd.csic.es/website1/Departamentos/ NEvolEcol.aspx MIGUEL TEJEDO is CSIC Assistant Professor of Research at the Biological Station of Doñana in Seville. His current interest is the analysis of thermal adaptations of amphibians to their local climatic environments. The main objectives are to provide a physiological basis of vulnerability to global change in tropical and temperate frogs and to understand whether thermal evolution is a potential engine of frog species radiation in tropical mountains. Given the ongoing high levels of deforestation in South America, alongside a raft of other vulnerability factors, Tejedo is not optimistic about the chance of survival for tropical and subtropical ectotherms. However, potential avenues do exist through which the risk posed by heat stress could be mitigated, such as the construction of ponds in shaded microenvironments and the upkeep of fragmented canopies. Although assistance on a large scale may not yet be forthcoming from natural resource agencies, the Evolutionary Ecology Group at the Doñana station has provided the tools for a better understanding of the phenomena affecting these species’ safety. WWW.RESEARCHMEDIA.EU 73