Rhythmic behaviours are influenced by temperature - significant for climate change responses

One significant question with climate change is that although temperature increases, the light-dark cycles at any location remain constant. Many of the responses of animals living in temperate and arctic (antarctic) areas depend on light-dark cycles. If the responses depending on light are affected by temperature, they may occur at inappropriate times in a climate change situation.

This was the outset for our experiments, reported in JM Prokkola et al. (Journal of Experimental Biology, in press). We studied the transcriptional responses of Arctic charr, a polar fish species, acclimated to two temperatures in July-August. Significantly, the rhythmicity of transcription was quite pronounced at an acclimation temperature close to the upper temperatures experienced by the fish in their natural environment. The rhythmicity of transcription all but disappeared at lower acclimation temperature. Since feeding, reproduction, migrations etc. are cued by light rhythms, an effect of temperature on how genes react to light, i.e. temperature effects on circadian rhythms of transcription may affect all those responses negatively. Consequently, effects of climate change can be pronounced even when temperature changes are such that they can easily be tolerated, e.g., by a fish population: any responses normally cued by light rhythm may occur at inappropriate times.