doi:10.1038/nindia.2012.145 Published online 30 September 2012
Fruit fly that emerge out of their pupal cases during a particular time of the day exhibit enhanced accuracy and precision of circadian clocks, according a controlled experimental study that could provide insights into the evolutionary adaptation of Drosophila melanogaster.
In fruit flies, adults emerge in large numbers from the pupae every day within an 8–10 hour interval starting a couple of hours before dawn, when humidity is high and temperature low. This increases the chances of survival of the flies. It is believed that developmentally mature flies emerge during or before this period, while others who mature after this time need to wait until the next day.
This circadian clock also regulates a wide variety of physiological processes in the flies including their metabolism and behaviour.
The researchers proposed that artificial selecting the time for the fruit flies to come out of the pupae during 'peak emergence time' could provide insights into the genetic variation associated with the timing and how it is related to the 'circadian phenotype'. This could also have evolutionary advantages under varying environmental conditions.
The researchers undertook an artificial laboratory selection experiment where only flies emerging during a narrow window of 1 hour at 'emergence peak' were allowed to contribute to the next generation. They did this for 80 generations of flies. The researchers found that with increasing generations, flies selected for emergence in a narrow window of time evolved circadian rhythms with enhanced accuracy and precision.
They claim this to be the first such study demonstrating that stabilizing selection for timing of adult emergence results in reduced inter- and intra-individual variance in circadian rhythms.