The Increase in Unusually Colored Zebras: A Sign of Fragmented Habitats Harming Populations
Zebras are typically recognized by their distinctive black and white striped coats, but in recent years, there has been a noticeable rise in individuals born with unusual patterns, including spots, large black dots, or lighter stripes instead of the usual black ones.
Two genetically mutated zebras discovered in Kenya. (Photo: National Geographic).
Such cases—often caused by genetic mutations affecting melanin production—are rare among mammals. Thus, the increase of zebras with unusual coat colors, now accounting for up to 5% of a population near Lake Mburo in Uganda, has prompted scientists to investigate the underlying causes.
Although the plains zebra (Equus quagga) is the least threatened among the three zebra species, its numbers have declined by 25% since 2002, with approximately 500,000 individuals scattered from Ethiopia to South Africa. Fragmented habitats due to fences, roads, and human development have pushed zebra populations, such as those around Lake Mburo, into smaller territories and hindered migration between herds.
Migration is essential for populations as it introduces new genes, which is key to the long-term survival of a species. A lack of genetic flow can lead to inbreeding, eventually resulting in infertility, diseases, and other genetic defects.
Another zebra displaying light patches across its black and white spots. (Photo: National Geographic).
“The increasing observation of zebras with strange patterns at Lake Mburo makes me wonder if this population is experiencing inbreeding,” said Brenda Larison, an evolutionary stripes researcher at the University of California, Los Angeles.
To seek answers, Larison and her colleagues conducted genetic analyses on 140 plains zebras—including 7 with unusual colors—from nine locations across Africa, including key reserves like Namibia’s Etosha National Park and South Africa’s Kruger National Park.
The study’s findings, recently published in the journal Molecular Ecology, indicate that small, isolated zebra populations have lower genetic diversity and are more likely to produce individuals with abnormal coat colors, highlighting a direct link between genetic mutations and low genetic diversity.
Although the study focused on only 7 uniquely patterned plains zebras, Larison emphasized that the results could serve as a warning for the future of the entire species. “These genetic issues often arise before something truly serious occurs,” the researcher shared.
Most of the genetically mutated zebras discovered were juveniles, suggesting that their unusual colors might make them more susceptible to predators, thereby reducing their life expectancy in the wild.
“This phenomenon is still relatively unknown, and it is often referred to as ‘silent extinction.’ That is why research on genetically mutated zebras is critically important,” said Philip Muruthi, Vice President for Species Conservation at the African Wildlife Foundation in Nairobi, Kenya, who praised Larison and her team’s new findings.
