Data from: Circadian plasticity evolves through regulatory changes in a neuropeptide gene

Many organisms, including cosmopolitan drosophilids, show circadian
plasticity, varying their activity with changing dawn–dusk intervals[1].
How this behaviour evolves is unclear. Here we compare Drosophila
melanogaster with Drosophila sechellia, an equatorial, ecological
specialist that experiences minimal photoperiod variation, to investigate
the mechanistic basis of circadian plasticity evolution[2]. D. sechellia
has lost the ability to delay its evening activity peak time under long
photoperiods. Screening of circadian mutants in D. melanogaster/D.
sechellia hybrids identifies a contribution of the neuropeptide
pigment-dispersing factor (Pdf) to this loss. Pdf exhibits
species-specific temporal expression, due in part to cis-regulatory
divergence. RNA interference and rescue experiments in D. melanogaster
using species-specific Pdf regulatory sequences demonstrate that
modulation of this neuropeptide’s expression impacts the degree of
behavioural plasticity. The Pdf regulatory region exhibits signals of
selection in D. sechellia and across populations of D. melanogaster from
different latitudes. We provide evidence that plasticity confers a
selective advantage for D. melanogaster at elevated latitude, whereas D.
sechellia probably suffers fitness costs through reduced copulation
success outside its range. Our findings highlight this neuropeptide gene
as a hotspot locus for circadian plasticity evolution that might have
contributed to both D. melanogaster’s global distribution and D.
sechellia’s specialization.