Low-cost fluctuating-temperature chamber for experimental ecology

Commercially available fluctuating-temperature chambers are large and costly. This poses a challenge to experimental ecologists endeavouring to recreate natural temperature cycles in the laboratory because the large number of commercial chambers required for replicated study designs is prohibitively expensive to purchase, requires a large amount of space and consumes a great deal of energy. We developed and validated a design for economical, programmable fluctuating-temperature chambers based on a relatively small (23 L) commercially manufactured constant temperature chamber ($140US) modified with a customized, user-friendly microcontroller ($15US). Over a 1-week trial, these chambers reliably reproduced a real-world fluctuating (13·1–35·5 °C) body temperature regime of an individual frog, with a near-perfect 1 : 1 fit between target and actual temperatures (y = 1·0036x + 0·1366, R2 = 0·9977, 95% confidence interval for slope = 1·0026, 1·0046). Over 30-day trials, they also reliably p...