Long believed to have been a single species of mammal with multiple sub-species, giraffes are actually four different types of creatures which have not exchanged DNA through cross-breeding for millions of years, according to new research published in the journal Current Biology.
Study authors conservation biologist Julian Fennessy from the Giraffe Conservation Foundation (GCF), geneticist Axel Janke from the Senkenberg Research Institute in Germany and colleagues made the surprising discovery while analyzing the genes of the world’s tallest mammals.
Previously, all giraffes has been officially classified as the species Giraffa camelopardalis, but as Janke explained to the New York Times on Thursday, some of the differences in giraffe DNA are “so large that we have to in fact describe four new species. Some of the differences were as large or larger than the differences between brown bears and polar bears.”
As such, what started as an to see if different subspecies could be grouped together in protected areas without incident resulted in the identification of four distinct species – the southern giraffe, the Masai giraffe, the reticulated giraffe, and the northern giraffe – based on the team’s study of the creatures’ mitochondrial DNA, according to BBC News.
Reclassification could help shape future conservation efforts
As Fennessy told ResearchGate, he recruited Janke five years ago to help on a genetic testing project involving giraffes. He had been collecting tissue samples from the long-necked animals for well over a decade and wanted to see how similar or different each sub-species were. They tested the DNA of more than 200 giraffes from across Africa as part of the project.
First, they analyzed genetic markers from mitochondrial DNA, a group of genes located within the part of the cell that converts chemical energy from food into a usable form, and discovered a surprising level of genetic differentiation among the different subspecies of the creatures. Next, they expanded their research, looking at more giraffe populations and genetic markers, and found that genetic exchange among the different groups is rare and possibly even nonexistent.
“This genetic isolation defines them as distinct species, as opposed to subspecies,” Fennessy told ResearchGate. He added that they were “extremely surprised because from our observations the morphological and coat pattern differences between giraffe are minor… we were not interested in splitting or clumping giraffe, but we let the results speak for themselves, and the message is very clear.”
Based on their findings, the new species and subspecies are the southern giraffe (Giraffa giraffa), which includes the Angolan (G. g. angolensis) and South African (G. g. giraffa) subspecies; the northern giraffe (G. camelopardalis), which includes the Kordofan (G. c. antiquorum), Nubian (G. c. camelopardalis) and West African (G. c. peralta) subspecies; the darker-colored Masai giraffe (G. tippelskirchi); and the reticulated giraffe (G. reticulata).
University of Manchester zoology professor Matthew Cobb, who was not involved in the study, told BBC News that this was “an important finding that will enable conservation biologists to target their efforts and, perhaps, to come up with new conservation approaches in captivity or in the wild, based on the genetic similarities and differences between these groups.”
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Image credit: Thinkstock
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