Figure 1.
Flowchart summarising the experimental protocol.
Eggs were collected from nests laid overnight and immediately divided into two (15°C and 25°C) incubation treatments until tadpoles reached Gosner stage 20 (after 2–5 days). Tadpoles from each incubation treatment were then acclimated to either 15°C or 25°C for six weeks.
Figure 2.
Growth (mean ± s.e.) in total length of tadpoles hatched from eggs incubated at 15°C (A) and at 25°C (B) that have subsequently been acclimated to 15°C (blue circles) or 25°C (red circles).
Warm-acclimation tadpoles had significantly higher growth rates at weeks 5 and 6 (acclimation×time interaction), but incubation temperatures did not have a significant effect. N = 15–18 tadpoles per treatment group per week.
Figure 3.
Burst swimming speed (mean ± s.e.) of tadpoles hatched from eggs developed at 15°C (A) and at 25°C (B) that have subsequently been acclimated to 15°C (blue circles) or 25°C (red circles).
The lines show Gaussian reaction norms fitted to the data from cold (blue lines) and warm (red lines) acclimated animals. The amplitudes, breadths and modes of the reaction norms were determined by an interaction between incubation and acclimation temperatures (Table 1). N = 18 tadpoles per treatment and test temperature.
Table 1.
Bootstrap means and 95% confidence intervals (+/− CI) of amplitude (AMP), Mode, and Breadth of the Gaussian equations describing thermal reaction norms of swimming performance of tadpoles from the different treatments (TRT).
Figure 4.
Routine metabolic rates (mean ± s.e.) of tadpoles hatched from eggs developed at 15°C (A) and at 25°C (B) that have subsequently been acclimated to 15°C (blue circles) or 25°C (red circles).
Cold-acclimated tadpoles had significantly higher metabolic rates particularly at higher test temperatures (acclimation×test temperature interaction), but incubation temperatures did not have a significant effect. N = 18 tadpoles per treatment and test temperature.
Figure 5.
Activities of enzymes (mean ± s.e.) important for glycolytic (lactate dehydrogenase, LDH [A, B], and mitochondrial (citrate synthase, CS [C, D]; cytochrome c oxidase, COX [E, F]) energy (ATP) production.
Data from eggs incubated at 15°C are shown in the left panels, and those from eggs incubated at 25°C are shown in the right panels. After hatching, tadpoles were acclimated to either 15°C (blues circles) or 25°C (red circles). Enzyme activities were determined by interactions between incubation and acclimation temperatures (see text for details). N = 9 tadpoles per treatment.