Reading Between the Lines: Zebra stripes’ Adaptive Function in Anti-Parasite Defenses and Thermoregulation

Abstract

This study analyzes the evolutionary function of zebra stripes by testing two hypotheses: 1) stripes help zebras thermoregulate and 2) stripes reduce the disease burden of zebras by preventing the attack of disease-vectoring biting flies. Data was collected at Mpala Research Center and Lewa Wildlife Conservancy in Kenya during June-July 2017. Results from this study show support for both of the hypotheses tested. Zebra body temperature was significantly lower than that of control species in the field, which provides evidence that stripes induce a cooling effect. This effect was also observed in bottle experiments, where zebra-striped bottles cooled faster than both solid black and white bottles. Additionally, significantly fewer flies landed on both zebra species compared to waterbuck in the field. Fly choice experiments also showed that Stomoxys flies avoided landing on zebra skins, picking control skins a significantly greater proportion of the time. Marked interactions between the thermoregulation and biting fly hypotheses that this study examined provide evidence that the two hypotheses for zebra coloration functionality may work together. In conclusion, this study shows the potential for a synergistic, multifunctional role of zebra stripes.