A small increase in UV-B increases the susceptibility of tadpoles to predation

Journal of Experimental Biology

2013

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Animals may overcome the challenges of temperature instability through behavioural and physiological mechanisms in response to short-and long-term temperature changes. When ectotherms face the challenge of large diel temperature fluctuations, one strategy may be to reduce the thermal sensitivity of key traits in order to maintain performance across the range of temperatures experienced. Additional stressors may limit the ability of animals to respond to these thermally challenging environments through changes to energy partitioning or interactive effects. Ornate burrowing frog (Platyplectrum ornatum) tadpoles develop in shallow ephemeral pools that experience high diel thermal variability (>20°C) and can be exposed to high levels of UV-B radiation. Here, we investigated how development in fluctuating versus stable temperature conditions in the presence of high or low UV-B radiation influences thermal tolerance and thermal sensitivity of performance traits of P. ornatum tadpoles. Tadpoles developed in either stable (24°C) or fluctuating temperatures (18-32°C) under high or low UV-B conditions. Tadpoles were tested for upper critical thermal limits, thermal dependence of resting metabolic rate and maximum burst swimming performance. We hypothesised that developmental responses to thermal fluctuations would increase thermal tolerance and reduce thermal dependence of physiological traits, and that trade-offs in the allocation of metabolic resources towards repairing UV-B-induced damage may limit the ability to maintain performance over the full range of temperatures experienced. We found that P. ornatum tadpoles were thermally insensitive for both burst swimming performance, across the range of temperatures tested, and resting metabolic rate at high temperatures independent of developmental conditions. Maintenance of performance led to a trade-off for growth under fluctuating temperatures and UV-B exposure. Temperature treatment and UV-B exposure had an interactive effect on upper critical thermal limits possibly due to the upregulation of the cellular stress response. Thermal independence of key traits may allow P. ornatum tadpoles to maintain performance in the thermal variability inherent in their environment.

Section: Methodsmentioning

confidence: 99%

Temperature and UV-B insensitive performance in tadpoles of the Ornate burrowing frog: an ephemeral pond specialist

Kern

Cramp

Journal of Experimental Biology

2013

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“…Other studies have measured correlates of fitness such as locomotor performance [59], anti-predator morphology and behaviour [60], and age and size at metamorphosis [61], and have demonstrated that these are negatively impacted by exposure to UVR [62][63][64][65]. Only two studies that we know of have used predation trials to determine that exposure to increased UVR increases the susceptibility of tadpoles to predation [66,67]. Romansic et al [67] attributed this increased susceptibility to predation to UVR-induced tail deformities that may have impaired tadpole swimming Xenopus laevis Artificial lamps [196] Limb and digit malformations Hypsiboas pulchellus Artificial lamps [69] Lithobates pipiens Ambient sunlight [185,186] Artificial lamps [58,200] Rana temporaria Artificial lamps [63] Jaw malformations Hypsiboas pulchellus Artificial lamps [69] Locomotion performance…”

Section: Effects Of Uvr On Amphibiansmentioning

confidence: 99%

Drivers of amphibian declines: effects of ultraviolet radiation and interactions with other environmental factors

Alton

2017

Clim Chang Responses

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As a consequence of anthropogenic environmental change, the world is facing a possible sixth mass extinction event. The severity of this biodiversity crisis is exemplified by the rapid collapse of hundreds of amphibian populations around the world. Amphibian declines are associated with a range of factors including habitat loss/ modification, human utilisation, exotic/invasive species, environmental acidification and contamination, infectious disease, climate change, and increased ultraviolet-B radiation (UVBR) due to stratospheric ozone depletion. However, it is recognised that these factors rarely act in isolation and that amphibian declines are likely to be the result of complex interactions between multiple anthropogenic and natural factors. Here we present a synthesis of the effects of ultraviolet radiation (UVR) in isolation and in combination with a range of naturally occurring abiotic (temperature, aquatic pH, and aquatic hypoxia) and biotic (infectious disease, conspecific density, and predation) factors on amphibians. We highlight that examining the effects of UVR in the absence of other ecologically relevant environmental factors can greatly oversimplify and underestimate the effects of UVR on amphibians. We propose that the pathways that give rise to interactive effects between multiple environmental factors are likely to be mediated by the behavioural and physiological responses of amphibians to each of the factors in isolation. A sound understanding of these pathways can therefore be gained from the continued use of multi-factorial experimental studies in both the laboratory and the field. Such an understanding will provide the foundation for a strong theoretical framework that will allow researchers to predict the combinations of abiotic and biotic conditions that are likely to influence the persistence of amphibian populations under future environmental change.

“…The military strategy of defoliation, whereby American forces dumped hundreds of thousands of tonnes of herbicides on forests in Vietnam in the 1960s and 1970s, has caused large-scale deforestation and pollution, the effects of which are still present today [22]. At a global scale, the increase in ultra-violet (UV) radiation as a result of hydrofluorocarbon release can affect ecosystems by disrupting different lifehistory stages of vulnerable species, and its effect may be compounded by other stressors such as pollution [23,24].…”

Section: Human Activity Modifies the Abiotic And Biotic Environmentsmentioning

confidence: 99%

Determining environmental causes of biological effects: the need for a mechanistic physiological dimension in conservation biology

Seebacher

2012

Phil. Trans. R. Soc. B

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198

187

The emerging field of Conservation Physiology links environmental change and ecological success by the application of physiological theory, approaches and tools to elucidate and address conservation problems. Human activity has changed the natural environment to a point where the viability of many ecosystems is now under threat. There are already many descriptions of how changes in biological patterns are correlated with environmental changes. The next important step is to determine the causative relationship between environmental variability and biological systems. Physiology provides the mechanistic link between environmental change and ecological patterns. Physiological research, therefore, should be integrated into conservation to predict the biological consequences of human activity, and to identify those species or populations that are most vulnerable.Keywords: global change; climate change; land clearing; adaptation; acclimation; ecological successConservation Physiology may be defined as the application of physiological theory, approaches and tools to elucidate and address conservation problems with the aim to provide a mechanistic understanding of how environmental disturbances and threatening processes impact physiological responses and thereby ecological function, population persistence, and species survival.