The known biological world is organized by two powerful timing mechanisms. One, the circadian clock, organizes the most basic metabolic events that allow plants and animals to survive on a daily basis. The other mechanism, the photoperiodic timer, organizes seasonal events including reproduction, migration and hibernation. Discordance in either of these two timing mechanisms is lethal. Yet, the connections between and the integration of the circadian clock and the photoperiodic timer are poorly understood in insects, the most abundant, diverse and, in some cases, most dangerous animals on Earth. This research will reveal the evolutionary genetic connection between these two biological timing mechanisms using the pitcher-plant mosquito, Wyeomyia smithii, which is uniquely suited to this study. Wyeomyia smithii lives in a strong seasonal gradient that includes both a mild sea-level climate and a harsh mountain climate, all in populations located in North Carolina. Hence, W. smithii shows great variation in its seasonal timing while at the same time expresses typical circadian behavior at all elevations. Using five well-established circadian clock genes, we will determine which, if any, of these genes control the seasonal timer in W. smithii. These experiments will represent the first test of the rhythmic expression of the circadian clock genes, and of the genetically based photoperiodic mechanism in a rigorous, real-world experiment.
The research on the evolutionary genetics and physiology of the photoperiodic timer by these researchers was the first demonstration that recent rapid climate change is driving genetic change in animals. As the climate continues to warm, increasing numbers of tropical diseases, including dengue fever, West Nile virus and malaria, carried by insects in the tropics and subtropics, are invading and will continue to invade the United States and other temperate regions of the world. Identifying the genes underlying the connections between the major biological timing mechanisms will provide a powerful tool for targeting, mitigating and interrupting these invasions. This lab will continue to participate in a wide variety of media productions, workshops, and outreach to the lay community. W. E. Bradshaw and C. M. Holzapfel are collaborating with the US Department of Agriculture to determine genetic relationships of mosquito vectors of human and livestock diseases using our next-generation genomic approaches. Funding of this research will enable these investigators to continue their long tradition of undergraduate research training.
