How sensible are cold temperate tadpoles to climate change? Combining thermal physiology and niche models

PEROTTI MG; BONINO, M. F.; FERRARO, D.P.; CRUZ, F.B.

ZOOLOGY

ELSEVIER GMBH

Año: 2018 vol. 127 p. 95 - 105

0944-2006

The use of bioclimatic envelope models to study the interaction between climate and the physiology of live organisms is, in some cases, a useful approximation of species? potential vulnerability to climate change. These new predictive methods, and the combination of physiological performance curves and models, has raised new insights and contributed more information on the mechanistic links between the species? current distribution ranges and climate. Ectotherms are particularly vulnerable to climate change, given their natural dependence on environmental temperatures, and amphibians are particularly interesting because of their complex life cycle in terms of the different lifestyles of adults and larvae. Tadpoles may regulate their body temperature behaviorally, using suitable thermal microhabitats, but they may be limited to thermoconforming. Thus, their physiological responses may be the result of adjustment to the local thermal limits experienced in their ponds and/or compensatory adjustments in physiological performance. We studied three anuran tadpole species present in Argentina and Chile, which differ in their distributional ranges and biology. Pleurodema thaul and P. bufoninum have broad latitudinal and altitudinal ranges and tadpoles are seasonal (spring-summer); whereas Batrachyla taeniata (Batrachylidae) has a restricted geographic distribution range associated with Nothophagus forest (central-south Chile and south Argentina), and the tadpoles present an overwintering strategy. We hypothesize that a species restricted in distribution like Batrachyla is more susceptible to climate change than the Pleurodema species that belong to a genus with a broad distribution (from the tropics to southern latitudes), and are expected to cope with potential changes in temperature in the different environments they inhabit throughout their distribution. Our goal is to test whether these species can buffer the potential effects of climate warming, using Ecological Niche Models (ENMs) to make projections as to the future distribution of these species, and the outcomes of their thermal attributes (Critical Thermal limits, optimal temperature, and locomotor performance breadth), as empirical evidence of their capacity to cope with future climate changes. We also evaluate their potential ?vulnerability" on a distributional range level, using different indicators from the ENMs for current and future scenarios, interpreting them as a function of their thermal traits. We find that Pleurodema species show broader performance curves, related to their occurrence over a large geographic range, while the geographically restricted Batrachyla taeniata shows narrower thermal breadth, but better locomotor performance in warmer conditions. The modeled distributions, combined with empirical physiological results, suggest that these three anurans are not severely threatened by climate change. However, we are aware that in the context of climate change the risk level is increasing, and a retraction of their distribution range might be possible for some species (Pleurodema); some local population extinctions may happen, particularly for the narrowly distributed Batrachyla taeniata.