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Zebra with no stripes9/18/2023 ![]() ![]() ![]() “However, we remain in the dark as to precisely what visual, perceptual or cognitive mechanism drives the avoidance of striped pelage as flies make landing choices. “We believe our results strongly implicate a visual mechanism that operates at distances within the range at which dipteran (insect) eyes can resolve stripes, and one in which all stripes within the natural range of stripe width expressed by zebras have an equally strong effect on fly landing preferences. There may be an adaptive reason for this, they said, or it may simply be a matter of ontogeny - the process of individual development from a single cell to an adult organism. “But if narrower stripes are not better at deflecting biting flies, why are stripes narrowest in these regions of the body? This has been suggested to align with the anti-parasite function of zebra stripes, as flies will often take flight from vegetation and cruise close to the ground, encountering the legs or face of a grazing zebra before other parts of the body. “In all zebra species, stripes are the narrowest on the face and legs. Zebras grazing in Kruger National Park, South Africa. “Our finding that stripe width did not alter fly repulsion also addresses proposed explanations for the variation in stripe width between different parts of the zebra body. ![]() Variations in stripe width thus appear to be associated with evolutionary selection pressures other than biting flies. “They are simply not necessary to repel flies from landing.” Visual effects occurring at long distances - that is, where flies have trouble distinguishing zebras from background landscapes - or sudden “visual transformations” as flies approach and stripes come into view, may still occur, they said. ![]()
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