Behaviour 2019
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Circadian rhythms and light cycles affect predation by spiders from different temporal niches
Brett Seymoure1-4, Onecia Adams3, Kate Frauenheim2,3, Katie Jones1,2, Rachel Rhee1,2, Arjun Sahai4, Leticia Classen-Rodriguez4, Amanda Koltz1,2, Kasey Fowler-Finn1,4, Anthony Dell1,3. 1Living Earth Collaborative, St. Louis, MO, United States; 2Washington University in St. Louis, St. Louis, MO, United States; 3National Great Rivers Research and Education Center, Alton, IL, United States; 4Saint Louis University, St. Louis, MO, United States

Light dictates animal behavior through light dependent systems such as circadian rhythms and vision. Circadian rhythms dictate metabolism and motivate foraging whereas visual abilities guide foraging, mating, and many other vital behaviors. Most behaviors of arthropods are cyclical and entrained by light environment, which varies throughout the day. It is currently unknown how organisms from different temporal niches (diurnal vs nocturnal) cue into time and light levels for foraging. We tested functional responses of diurnal and nocturnal wolf spiders foraging on flightless D. melanogaster at different times (night, twilight, day) and under different lighting (starlight, twilight, daylight). We examine hypotheses on individual variation (size and visual traits) influencing foraging through real-time video tracking of predators. We hypothesize that light levels and visual abilities drive movement in these visually guided hunters, and movement strongly influences the rate of encounters, resulting in greater predation. As artificial light continues to expand spatially and in intensity, these findings illuminate the consequences of unnatural light.