Giraffe not single species, but four!
Thu, 8th Sep 2016
Giraffe have long been assumed to be a single species. However, their genes suggest otherwise, and a new study argues that there are in fact four distinct species of the animal.
“There’s very little research on giraffe…we’re among the first to make genetic studies,” Axel Janke told The Naked Scientists, “They have simply been overlooked by science”.
Working with the Giraffe Conservation Foundation, Janke and his team from the Senckenberg Centre and Goethe University in Germany studied the genes of 190 giraffe from across Africa.
Previously, scientists recognised nine subspecies of giraffe - varieties thought to be within the same species, but with some slightly different genetic adaptations to their environment.
Janke’s team set out to understand how subspecies from different regions of the continent were related - information that would help conservationists better protect our tallest mammals.
However, their findings completely revised the old classifications, instead grouping giraffe genes into four distinct clusters, some containing two or three subspecies.
Since these groups are genetically isolated, the researchers conclude that they should be recognised as four different species: the southern giraffe, the Masai, the reticulated, and the northern giraffe.
Although they look deceptively similar, the species can be identified by subtle differences in their coat patterns.
Janke argues the implications are huge.
“They’re as different as, for example, the genes between a polar bear and a brown bear,” he says.
The findings are unexpected because the species are known to interbreed in captivity. However, they do not mate in the wild, giving them distinctly different genetics.
The reason for this separation remains a mystery. Wild giraffe have be known to roam widely, and geographical barriers are not thought to prevent the animals from mixing.
Latest estimates place the number of giraffe in the wild at approximately 90,000. This is significantly fewer than some protected species, such as African elephants, which are currently thought to number around 470,000.
According to the Giraffe Conservation Foundation, giraffe populations have declined by more than 35% in the last twenty years. A number of factors have contributed to the dwindling numbers, including poaching and loss or degradation of their natural habitats.
Despite this, giraffe remain listed as of ‘least concern’ on the IUCN’s current Red List of Threatened Species. This is largely due to a lack of accurate information on giraffe populations - a situation that the IUCN and the Giraffe Conservation Foundation are working to change.
Janke hopes that his team’s study, which is published in the journal Current Biology, will provide valuable evidence on which to base future conservation efforts.
“Now we have four species, and some of these species have only numbers of five or eight thousand individuals, so they need to be protected.”
The team are now researching how the species became separate, and what keeps them separate today. This could also help scientists better understand how animals evolve into different species.
“Giraffe are young species,” Janke adds, “They have separated only some 100,000 years ago...so their speciation, in progress in front of our eyes, [makes them] a very nice model organism.”