WHICH IS THE RIGHT TEMPERATURE FOR SWIMMING? THERMAL SENSITIVITY OF TEMPERATE AND SUBTROPICAL LARVAE OF AMPHIBIANS

KATZENBERGER, MARCOS; TEJEDO, MIGUEL; DUARTE, HELDER; MARANGONI, FEDERICO; BALDO, DIEGO; BELTRÁN, J.F.; MARTÍ, DARDO; RICHTER-BOIX, ALEX

Sevilla

Congreso; XI Congreso Luso – Español de Herpetología / XV Congreso Español de Herpetología.; 2010

Amphibian physiological performance is highly affected by environmental thermal characteristics. With expected global warming, the ability to perform ecologically relevant functions may be compromised, affecting their general fi tness. Assessing how a species performs at a range of temperatures will highlight its susceptibility to temperature changes and subsequently its risk of extinction. Tropical ectotherms are considered to be more vulnerable to warming than higher latitude species, because environmental temperatures are closer to their optimum. To verify this hypothesis, we analyzed the swimming performance of amphibian larvae of different species from a temperate community in the Iberian Peninsula (water temperature range: 5°C - 34°C) and two subtropical communities from Argentina that widely contrast in their thermal regimen (openforest Gran Chaco community water temperature range: 20°C - 42°C and closed-canopy forest Misiones community water temperature range: 16°C - 28°C) to obtain their specifi c thermal performance curve (TPCs). We found that the optimum temperature is positively correlated with habitat temperature. This means that species living in higher pond water temperature tend to have higher optimum temperature for locomotor performance. However, higher optimum temperature does not translate into broader thermal safety margins (TSM = Optimum temperature – mean habitat temperature). Most species from the Grand Chaco community are already operating very near or even above their physiological optimum and any increase in temperature may have catastrophic consequences. Contrarily, temperate species, generally living in cooler sub-optimum environments, may in fact benefi t or not be affected at all. Since “where you live” matters, species from the Misiones community may benefi t from the protection of the canopy which reduces temperature fl uctuation and pond water heating. Therefore, susceptibility to global warming depends mainly on the actual environmental thermal conditions and it closeness to their optimal temperature.