Involvement of clock genes in seasonal, circadian and ultradian rhythms of Nasonia vitripennis

Natural selection and survival of the fittest are important ingredients of evolution. A proper timing of activities, according to seasons, days or even seconds, is crucial for survival. Nasonia vitripennis is a parasitic wasp that is capable of timing activities on different time-scales: a type of hibernation called diapause (seasonal), daily activities (circadian) and courtship behavior (ultradian). Populations of N. vitripennis in Northern Europe, start diapause sooner than populations in the South, and also differ in many other rhythmic behavioral characteristics. Because variants of the clock gene period, a gene that is known to regulate timing of daily activities, are correlated with this difference in diapause, the circadian clock may also be important to regulate seasonal diapause induction. By analyzing the importance of period expression on daily activity, on the expression of other clock genes and on courtship behavior, I could design two models how period can be involved in timing activities on different time-scales. Both models support the hypothesis that there is an evolutionary link between the circadian clock and the seasonal photoperiodic response of the parasitoid wasp Nasonia vitripennis, a conclusion that should be validated for other organisms as well.