DNA Reveals Giraffes are 4 Species–Not 1

From Scientific American:

Researchers previously split giraffes into several subspecies on the basis of their coat patterns and where they lived. Closer inspection of their genes, however, reveals that giraffes should actually be divided into four distinct lineages that don’t interbreed in the wild, researchers report on 8 September in Current Biology. Previous genetic studies have suggested that there were discrete giraffe populations that rarely intermingled, but this is the first to detect species-level differences, says Axel Janke, a geneticist at Goethe University in Frankfurt, Germany, and the study’s senior author.

“It was an amazing finding,” he says. He notes that giraffes are highly mobile, wide-ranging animals that would have many chances to interbreed in the wild if they were so inclined: “The million-dollar question is what kept them apart in the past.” Janke speculates that rivers or other physical barriers kept populations separate long enough for new species to arise.

The study tracked the distribution of 7 specific genetic sequences—chosen to enable researchers to measure genetic diversity— in nuclear DNA from skin biopsies of 190 giraffes. They also looked at the animals’ mitochondrial DNA. The sequences fell into four distinct patterns that strongly suggested separate species. Janke says that each of the four species is about as different from each other as the brown bear (Ursus arctos)is from the polar bear (Ursus maritimus).

The researchers suggest replacing the current species name, Giraffa camelopardalis,with four new ones: the southern giraffe (G. giraffa), found mainly in South Africa, Namibia and Botswana; the Masai giraffe (G. tippelskirchi) of Tanzania, Kenya and Zambia; the reticulated giraffe (G. reticulata) found mainly in Kenya, Somalia and southern Ethiopia; and the northern giraffe (G. camelopardalis), found in scattered groups in the central and eastern parts of the continent. The one remaining subspecies is the Nubian giraffe (G. camelopardalis camelopardalis) of Ethiopia and South Sudan. It …

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