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Description
Marine midges of the genus Clunio inhabit the intertidal zone along rocky coasts around the world. Clunio’s life cycle is adapted to the tides. Adults of Clunio only emerge and reproduce during full moon and new moon, when the spring tides expose most of the intertidal zone. To this end, Clunio evolved endogenous time keeping mechanisms. These include the enigmatic circalunar clock, which restricts adult emergence to spring tide days, and the circadian clock, which restricts adult emergence to the time of low tide.
We investigated the role of the circadian clock in circalunar time keeping by exposing midges to non-24h day cycles. The observed linear relationship between daylength and the circalunar clock’s period suggests that Clunio is counting days, or rather circadian oscillations, in order to measure the lunar cycle. We now further explore if Clunio’s circalunar counter is derived from a photoperiodic counter using comparative transcriptomics.
In an evolutionary perspective, the circalunar clock mechanism of Clunio and another marine midge appears to be distinct from those of marine algae and annelids.
