Circadian systems evolved as a mechanism that allows organisms to maintain internal temporal order and anticipate the daily environmental changes caused by the rotation of Earth. Although the biochemical components underlying the molecular oscillations have been well characterized, less is known about the physiological mechanisms that connect clock neuron networks to their output pathways and allow the circadian control of physiology and behavior. Timing of behavioral outputs is essential for survival, as it determines an animal`s ability to be physiologically ready for resources and potential mates. In this context, aggression is a key behavioral pattern, which likely evolved in the context of competition over limited resources. In the lab we study how circadian clock neurons connect with their downstream targets to control rhythms in key social behaviors like aggression.


Life evolved in a profoundly rhythmic environment with large amplitude changes in environmental light. These cycles of bright days and dark nights provided strong entrainment cues for the circadian clock, which influences almost all aspects of physiology and behavior. In modern urban environments, human populations have become less exposed to sunlight during the day as well as increasingly exposed to illuminated nights. Abnormal light environments (ALEs) have been shown to affect circadian rhythms, immune and metabolic functions, behavior and health-span in animal models, and an increasing amount of evidence suggests that it negatively influences mood and physiology in human populations. We are using the genetically tractable Drosophila melangaster to study the effect of ALEs on neurophysiology and behavior throughout an animal´s life.


Aggression is a complex social behavior that  likely evolved in the context of competition for resources. Although interactions between genes, environmental signals, and hormones influence the manifestation of aggression, the core circuitry underlying aggressive behavior appears to be hardwired in the nervous system, as animals with no previous social experience can engage in normal agonistic encounters  As. for most species, aggression in Drosophila melanogaster is sex-specific, suggesting that it is differentially hardwired in the nervous systems of males and females. The study of innate sexually dimorphic behaviors in genetically tractable organisms offers unique opportunities to understand how the underlying neuronal circuitry is genetically specified.


Department of Neuroscience and Behavior

Barnard College

3009 Broadway

416A Milbank Hall

NYC, NY 10027

©2019 by the Fernandez Lab. Created with

Image credits: Orie Shafer