Up until now, scientists had only recognized a single species of giraffe made up of several subspecies. However, Scientists from the Senckenberg (World of Biodiversity – Institute) in Germany and the Giraffe Conservation Foundation recently have analysed the genetic relationships of all major populations of giraffe in the wild. This large study on the genetic make-up of giraffe, published on 8 September in the journal Current Biology, shows that there are four distinct giraffe species. The unexpected results are based on analyses using several nuclear marker genes of more than 100 animals. The new insights are set to improve protection efforts of these endangered animals in Africa.
Despite their large size and iconic presence, giraffe have been incompletely explored until now, with many aspects of their biology poorly understood. Latest estimates have revealed that over the past 30 years giraffe numbers have plummeted from over 150,000 to less than 100,000 individuals across their range in Africa. Traditionally giraffe are classified as one species with nine subspecies based on coat patterns, ossicone (horn) structure and geographical distribution – now, this view has to be thoroughly revised.
“Consequently, giraffe should be recognized as four distinct species despite their similar appearance,” added Janke.
About five years ago, Julian Fennessy of Giraffe Conservation Foundation (GCF) in Namibia approached Janke to ask for help with genetic testing of the giraffe. Fennessy wanted to know how similar (or not) giraffes living in different parts of Africa were to each other, whether past translocations of giraffe individuals had inadvertently “mixed” different species or subspecies, and, if so, what should be done in future translocations of giraffes into parks or other protected areas.
The study that leads to a new classification is based on 190 skin biopsy samples from all previously recognized giraffe subspecies, which were collected by the GCF and partners over the past decade including in remote areas and civil war zones. These giraffe DNA samples were then analysed by Janke’s research group at the Senckenberg Biodiversity and Climate Research Centre in cooperation with colleagues from the Senckenberg Natural History Collections of Dresden, Germany. The sample set included for the first time the elusive Nubian giraffe, the nominate subspecies (G. c. camelopardalis) – the “camel-leopard” – described by Linnaeus in 1758 on the basis of a 200-year-old record.
(1) southern giraffe (Giraffa giraffa), comprising two distinct subspecies, Angolan (G. g. angolensis) and South African giraffe (G. g. giraffa);
(2) Masai giraffe (G. tippelskirchi);
(3) reticulated giraffe (G. reticulata); and
(4) northern giraffe (G. camelopardalis), which includes Nubian giraffe (G. c. camelopardalis), West African giraffe (G. c. peralta) and Kordofan giraffe (G. c. antiquorum) as distinct subspecies.
The large-scale analysis of giraffe DNA also yielded further surprising insights. The formerly recognized subspecies of Rothschild’s giraffe (G. c. rothschildi) turned out to be genetically identical with Nubian giraffe, and thus should be considered similar to this subspecies. Similarly, the genetic studies supported previous findings by the team that could not differentiate the formerly recognized subspecies Thornicroft’s giraffe (G. c. thornicrofti) with Masai giraffe (G. c. tippelskirchi). Additionally, research into the history of the distinct species showed that their last common ancestor lived about 0.4−2.0 million years ago, which yields a rate of speciation that is typical for mammals.
The discovery has significant conservation implications, the researchers say, noting that the International Union for Conservation of Nature and Natural Resources (IUCN) Species Survival Commission Giraffe and Okapi Specialist Group recently submitted an updated proposed assessment of the giraffe on the IUCN Red List taking into consideration their rapid decline over the last 30 years.
“Species conservation is based on understanding the numbers, range and threats to the species. To date, the estimated total number of all giraffe has until now not been considered a particular threat for the species’ survival. However, as we now recognize four distinct species as well as some genetically unique subspecies, some of their biodiversity is very much under threat,” explains Janke. “In particular, GCF estimates that there are maybe as few as 400 West African giraffe remaining in the wild and restricted to a small communal area in Niger. Although it is not a distinct species, this subspecies is genetically unique and requires increased special protection along with the other distinct species.”
“With now four distinct species, the conservation status of each of these can be better defined and in turn added to the IUCN Red List,” Fennessy says.
This study was supported by the State of Hesse’s funding program LOEWE, the Leibniz Association, the Giraffe Conservation Foundation, the Leiden Conservation Foundation, the Auckland Zoo, and various African government partners and international supporters.