While they're not alone in the vast wonders of Africa's abundant plains, zebras in particular have posed quite a quandary to scientists in past decades. Their unique striping of black and white have always sparked interest in their study, but the ever failing hypotheses quickly discouraged the discovery of their significance-if any at all. But while many researchers have failed in associating the stripes with social order of a herd or even as camouflaging tactics in the wild, a new study published this month in the journal Royal Society Open Science, researchers have discovered that the stripes are much more like a tan than we think.
"The adaptive significance of zebra stripes has thus far eluded understanding. Many explanations have been suggested, including social cohesion, thermoregulation, predation evasion and avoidance of biting flies" lead researcher of the study, Brenda Larison says. "Plains zebra striping pattern varies regionally, from heavy black and white striping over the entire body in some areas to reduced stripe coverage with thinner and lighter stripes in others. We examined how well 29 environmental variables predict the variation in stripe characteristics of plains zebra across their range in Africa. In contrast to recent findings, we found that temperature successfully predicts a substantial amount of the stripe pattern variation observed in plains zebra."
Assuming, like many studies before them, that zebra striping is an adaptive trait, the researchers of the study sought out to investigate whether or not the hypothesis could be empirically supported that these stripes act in a way to thermoregulate the species.
"We found that environment, particularly temperature, was a significant predictor of zebra stripe patterns across their entire range in Africa" Larison says. "The stripe characteristics that were most readily explained by environmental variation were stripe thickness and definition on forelegs and hind legs, and the number of stripes and definition on the torso, suggesting that these traits are the most likely targets of selection."
Defining the stripes of each and every zebra they encountered, the researchers were able to apply standardized values in spite of the incredible variation among the species.
Overall the random forest model utilized analyzed a set of 29 environmental variables to determine the conclusion that ambient temperature had a significant impact on the density and abundance of stripes in nearby zebra. But with multiple possible environmental factors at play, the researchers have yet to rule out other covariants that may too have a hand in how many stripes we see. With climate changing ever-faster, and other variables out in the plains, the researchers are eager to continue their studies, however, know now that thermoregulation is clearly one reason why zebras get their stripes.
"As this association between striping and temperature may be indicative of multiple biological processes, we suggest that the selective agents driving zebra striping are probably multifarious and complex" Larison says. "This correlation with temperature may be explained by more than one causal mechanism and will require further investigation."
