Study out of UC Davis uncovers the benefit of having stripes.
Through the use of statistical models, researcher Tim Caro of the University of California at Davis has found a strong correlation between the presence of stripes in zebras and the presence of blood-sucking flies.
For a long time, numerous theories have circulated explaining the presence of the zebra’s trademark pattern. A popular one was that the presence of stripes was used to confuse predators. Others believed that the stripes served as a cooling mechanism for the mammals, some form of camouflage, or a tool for social interaction.
To answer the question of how zebras got their stripes, researchers looked beyond zebras and into the equid family. The equid family is a branch of mammals that includes horses, zebras, donkeys, and approximately twenty other genera. It is a common trait among all these animals to have some form of striping on a portion of their bodies. Researchers were interested in looking at where these stripes were located on the animals, as well as the concentration.
Next, researchers sorted the location of where both the non-striped and striped members of the equid family lived. By mapping the location of both the current and extinct members of the equid family, a set of correlations appeared. The presence of stripes is more common in locations that blood-sucking and potentially disease-carrying insects are found.
The correlation between stripes and insects held true against multiple statistical models that measured the range predators, distribution of forest, and numerous other environmental factors.
Brenda Larison of the University of California at Los Angeles, however, remains skeptical of the findings. She explains that the development of the zebra’s stripes is most likely much more complex, and she anticipates further discoveries. She also points out that the majority of the other theories have yet to be tested. This, she explains, causes “a lack of direct evidence.”
Then there is still the remaining question of why a fly would rather a solid-coloured animal compared to that of a striped colour. It has been found that flies for some unknown reason do tend to avoid black and white surfaces.
Zebras, with their short hair, are very susceptible to flies. This could explain why zebras develop a uniform striped pattern compared to other members of the equid family, who developed stripes on a portion of their body.