Animals living at high latitudes have to cope with prominent seasonal changes in their environment. In summer, they are exposed to long days and short nights with pleasant temperatures that allow reproduction, whereas the short days and low temperatures in winter require special adaptations to survive such as frost resistance and reproduction arrest.
In contrast, animals living close to the equator experience very little seasonal changes allowing reproduction throughout the year. The circadian clock in the brain is known to control daily activity-rest rhythms and to provide an internal time reference for measuring day length. The latter is essential for a timely preparation for the winter.
We found that the molecular oscillations of the clock proteins Period (PER) and Timeless (TIM) in the brain of the fly differ under long summer and short winter days. Most interestingly, these flies also respond to short days with a change in the composition of their hydrocarbon (CHC) profile on the surface of the.
In order to understand the role of the circadian clock in day length measurements, we will use lab and wild-caught strains D. melanogaster. We will especially test whether there is a causal correlation between day length, PER/TIM oscillations, and cold resistance by investigating clock mutants that cannot normally adapt their clock to the seasons but remain in a quasi-permanent clock-winter- or clock-summer- state.
Our investigations will provide the first basis in understanding the role of the circadian clock in seasonal adaptation using the well characterized model D. melanogaster.