Robustness of Circadian Timing Systems Evolves in the Fruit Fly Drosophila melanogaster as a Correlated Response to Selection for Adult Emergence in a Narrow Window of Time

Abstract

Robustness is a fundamental property of biological timing systems that is likely to ensure their efficient functioning under a wide range of environmental conditions. Here we report the findings of our study aimed at examining robustness of circadian clocks in fruit fly Drosophila melanogaster populations selected to emerge as adults within a narrow window of time. Previously, we have reported that such flies display enhanced synchrony, accuracy, and precision in their adult emergence and activity/rest rhythms. Since it is expected that accurate and precise circadian clocks may confer enhanced stability in circadian time-keeping, we decided to examine robustness in circadian rhythms of flies from the selected populations by subjecting them to a variety of environmental conditions comprising of a range of photoperiods, light intensities, ambient temperatures, and constant darkness. The results revealed that adult emergence and activity/rest rhythms of flies from the selected stocks were more robust than controls, as they displayed enhanced stability under a wide variety of environmental conditions. These results suggest that selection for adult emergence within a narrow window of time results in the evolution of robustness in circadian timing systems of the fruit fly D. melanogaster. (Author correspondence: [email protected] or [email protected])

Keywords:

• Circadian
• Drosophila
• Light
• Photoperiod
• Precision
• Robustness
• Selection
• Temperature

ACKNOWLEDGMENTS

We thank Sheeba Vasu for comments, and Shahnaz and Kanika for help during the experiments. We thank University Grant Commission, Government of India, for financial assistance in the form of a research fellowship to N.K. We thank the three anonymous reviewers for carefully reading the manuscript and suggesting some very useful changes.

Declaration of Interest: This work was supported by funds from the Jawaharlal Nehru Centre for Advanced Scientific Research, Bangalore, India, which also provided assistance to N.M. in the form of summer research fellowship.

The authors report no conflicts of interest. The authors alone are responsible for the content and writing of the paper.