Microclimatic variation within a tropical biodiversity hotspot from a tadpole’s perspective

Studies on species responses to climate change have relied primarily on coarse-scale climatic data, but individual-level processes governing some of these responses occur in the domain of the microclimate, i.e., the climate in spatiotemporal scales relevant to organisms. We investigate the microclimatic diversity available for an anuran community within a small area (~ 1-km2) of a subtropical forest ecosystem, the Brazilian Atlantic Forest. We recorded 1 week of microclimatic temperatures at 10-min intervals in a set of waterbodies used by anuran larvae differing in physical structure, temporality and vegetation cover, for two reproductive seasons. We observed considerable variation in diurnal and nocturnal thermal profiles among waterbodies regarding thermal extremes, central tendencies and thermal variance. Temporary waterbodies displayed the most extreme and variable thermal conditions both at daytime and nighttime, with minimum temperatures as cool as 11°C and maximum temperatures surrounding the 40°C. Conversely, streams inside the forest showed the most stable diurnal and nocturnal thermal profiles, with water temperatures closely around 20°C. Moreover, waterbodies directly exposed to solar radiation exhibited more extreme and variable thermal profiles than those covered by canopy. This local variation in microclimatic conditions among waterbodies is compatible with the observed across macroecological gradients. The implications of this microclimatic heterogeneity for the thermal physiology of amphibians inhabiting these waterbodies are discussed. We highlight that studies on microclimate are the key to infer and predict species responses to climate change with underpinnings in individual-level processes.