Role of Temperature in Mediating Morning and Evening Emergence Chronotypes in Fruit Flies Drosophila melanogaster

Abstract

Following decades of research under controlled laboratory conditions, there has been growing interest in the recent past to study circadian rhythms in nature. Recent studies conducted under natural conditions have been fruitful in exploring several characteristics of circadian rhythms that remained cryptic and previously masked under standard laboratory conditions, reemphasizing that the complexity of circadian rhythms in nature increases multifold under the influence of multiple zeitgebers. However, our understanding of the contributions of different zeitgebers in shaping various rhythm characteristics still remains elusive. Previously, Vaze et al. reported that chronotype differences between the morning emerging (early) and evening emerging (late) populations of Drosophila melanogaster are considerably enhanced under natural conditions compared to standard laboratory conditions. In the present study, we assess the role of 2 primary zeitgebers in naturelight and temperatureindividually and in unison in driving chronotype differences. We report that when provided independently, temperature cycles enhance divergence between the early and late chronotypes more strongly than light, but when together, light and temperature appear to act antagonistically and that appropriate phase difference between light and temperature cycles is essential to promote chronotype divergence. Thus, our study highlights the importance of light and temperature, as well as their interaction with circadian clocks in mediating early and late chronotypes in fruit flies D. melanogaster.