Earn your stripes!
Updated: Jun 8, 2020
Grant’s zebra (Equus quagga boehmi) is the smallest of the seven subspecies of the plains zebra (Equus quagga) aka the common zebra. In Africa, Grant’s zebras roam grasslands and savannahs, eating coarse grasses that other grazing animals may not ingest. Though there are more wild populations of Grant’s zebra than other zebra species, they are not immune to environmental threats. The IUCN categorizes Grant’s zebra as near threatened with its population in decline, mostly due to habitat loss for agricultural development and human conflicts in their regions.
Of course, zebras are famous for their contrasting black and white stripes. Incredibly, there is still ongoing debate about why they sport their unusual striped pattern. Many functions have been proposed, including camouflage, repelling insects and thermoregulation [1,2,3].
Among some of the more recent findings on the matter of zebra striping is the correlation between the intensity and opacity of striping in zebras and their native environment’s temperature. Generally, zebra species that inhabit warmer climates have dark, broad stripes that cover most of their body. In the cooler regions near South Africa, the striping pattern is lighter, thinner, and may only cover the head and abdomen. Based on this finding, researches can now accurately predict what the zebras in different regions of Africa look like! Read more about this here.
The debate on how the zebra got its stripes goes all the way back to Charles Darwin and Alfred Russel Wallace. To bring in some genomics resources to weigh in on the question, we release today a de novo chromosome-length genome assembly for the Grant’s zebra. This is a $1K genome assembly with contig N50 = 89kb and scaffold N50 = 114Mb. This assembly was created with the help of two zebras: Ziggy from the Houston Zoo and Zena from Hearts and Hands Animal Rescue. Thank you, Nancy Nunke (Hearts and Hands Animal Rescue), Greg Barsh (Stanford University/Hudson Alpha) and Brenda Larison (UCLA) for their help with this assembly! Follow this link to visit the assembly page.
See below how the Grant zebra’s chromosomes relate to those of a domestic horse. That’s a lot of rearrangements for only ~4 million years separating the species! (Compare this, for example, to the very stable chromosomes in the cat family.)
Post by: Ruqayya Khan, Olga Dudchenko
P.S.: If you have ever wondered if the zebras are black with white stripes or white with black stripes, wonder no more; the questions has finally been definitively answered!
P.P.S.: Since Grant's derives from a subspecies designation and subspecific designations are somewhat dubious, on the assembly page we refer to the species as plains zebra.