Abstracts (first author)
Daily and seasonal changes in the locomotor activity of Drosophila montana flies is accompanied by changes in the expression of two circadian genes, period and timeless
Adaptation to daily and seasonal changes in environmental conditions is of crucial importance for the species living in northern latitudes. This includes the ability of the organisms to predict the forthcoming winter by sensing gradual changes in environmental cues early enough to be prepared e.g. by synchronizing their metabolic, developmental and behavioral processes along with the changing seasons. This forecasting system relies heavily on the function of two major molecular clock mechanisms, the circadian clock and the photoperiodic timer. The genetic and neuronal background of the circadian clock is well-known, but the possible role of circadian clock in the photoperiodic timer is under intense debate, partly due to the fact that most of the studies have been performed in D. melanogaster that is not adapted to live seasonally highly varying environments and possesses only mild seasonal photoperiodic responses. Our study species, D. montana, offers a unique opportunity to study these questions as this northern species shows clear circadian rhythms as well as robust photoperiodic responses.
We have studied the possible involvement of the circadian clock in seasonal adaptation by tracing the daily and seasonal rhythms in the locomotor activity of D. montana females and the function of two circadian clock genes, period and timeless, in conditions mimicking light and temperature conditions during ‘summer’ and ‘autumn’, when the females’ developmental pathway (direct maturation vs. reproductive diapause) is determined. D. montana flies shifted their evening activity, as well as the expression peaks of per and tim, towards an earlier time of the day along with a decrease in day length, suggesting that these genes are involved in seasonal adaptation. In addition, a decrease in D. montana’s locomotor activity, as well as the lower activity of diapausing females vs. the non-diapausing ones in late summer and autumn are clearly adaptive features on northern latitudes.