You would think that giraffes, the tallest land animals in the world, would be hard to overlook.
Yet, for centuries scientists may have missed a fundamental fact about these long-necked creatures: They aren’t one species, but rather four distinct ones.
“The genetic differences between giraffes is so large that we have to in fact describe four new species,” said Axel Janke, a geneticist from the Senckenberg Biodiversity and Climate Research Center in Frankfurt. “Some of the differences were as large or larger than the differences between brown bears and polar bears.”
Dr. Janke, along with Julian Fennessy from the Giraffe Conservation Foundation in Namibia and their colleagues, tested the DNA of nearly 200 giraffes from across Africa. They found genetic mutations that were present in certain groups and absent in others. The differences in mutation patterns, they said, were strong enough to classify the groups as distinct species. In some cases subspecies of giraffe were upgraded to being full-blown species. The team published its results Thursday in the journal Current Biology.
Until this point the African mammals were classified on the species level as Giraffa camelopardalis, or simply the giraffe. Now they will belong to one of four species: the southern giraffe, the Masai giraffe, the reticulated giraffe and the northern giraffe.
“Science thought there was one species and now genetics show there are four species,” Dr. Janke said. “All zoos across the world that have giraffes will have to change their labels.”
There are a few visible differences between the species, such as the jagged lines and dark spots on the Masai giraffe and the five hornlike structures on the northern giraffe, but for the most part they look pretty similar. The researchers did not find any examples of hybridization, or cross-mating between the groups in the wild.
The species might have diverged from one another relatively recently, about 1.5 million years ago, according to Dr. Janke. Humans and [bleep], for comparison, parted ways about six or seven million years ago, though some studies place that figure as far back as 13 million years.
Dr. Janke said that he’s not sure why it took so long for researchers to figure out that giraffes don’t all belong to the same species. He said that it may have to do with how little they are studied compared with some of Africa’s other wildlife like lions, elephants and rhinos.
The new finding has important implications for giraffe conservation, Dr. Janke said. Over the past 30 years giraffe numbers have dropped to about 90,000 individuals from about 150,000. Right now there are only about 4,750 northern giraffes and 8,700 reticulated giraffes.
“These 90,000, split up over four species, makes it immediately clear that the giraffes are threatened,” Dr. Janke said. “You see immediately there is urgent need for protection.”
