This study aimed at characterizing splice variants associated with circadian rhythms in intertidal copepods.</p><p>The experiment used copepods from San Diego, California, and Strawberry Hill, Oregon that had been acclimated to laboratory conditions for at least three generations.</p><p>Copepods were cultured in an incubator at 20C in one of two different light regimes: 8:16 or 12:12: Light:Dark cycle. For each treatment (population x light regime), 25-day old adult male individuals were sampled in pools of ~20 individuals five hours after the light turned on. Five replicates were collected from each treatment (total 20 samples).</p><p>Total RNA was isolated using Trizol reagent, and sequencing library was prepared with the NEBNext Ultra II Directional RNA kit, using 300-500 ng of total RNA as input.