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Last Updated: Friday, 21 December 2007, 23:38 GMT
Not one but 'six giraffe species'
Anna-Marie Lever
Science and nature reporter, BBC News
The world's tallest animal, the giraffe, may actually
be several species, a study has found.
A report in BMC Biology uses genetic evidence to show that
there may be at least six species of giraffe in Africa.
Currently giraffes are considered to represent a single
species classified into multiple subspecies.
The study shows geographic variation in hair coat colour is
evident across the giraffe's range in sub-Saharan Africa,
suggesting reproductive isolation.
"Using molecular techniques we found that giraffes can be
classified into six groups that are reproductively isolated
and not interbreeding," David Brown, the lead author of
the study and a geneticist at the University of California
Los Angeles (UCLA), told BBC News.
"The results were a surprise because although the giraffes
look different, if you put them in zoos, they breed freely."
Giraffe populations have dropped by 30%
over the past decade
Spots and maple leaves
The study also found that the two giraffe subspecies that live closest to each other - the
reticulated giraffe (Currently: Giraffa camelopardalis reticulate) in North Kenya, which has
reddish round spots; and the Maasai giraffe (Currently: Giraffa camelopardalis
tippelskirchi) in South Kenya - separated 0.5 to 1.5 million years ago.
These results are interesting as giraffes are highly mobile animals. They frequently range
over several hundred square kilometres and are capable of long distance movements of
some 50-300km (30-170 miles), which
means different populations are likely to
meet.
SOME GIRAFFE FACTS
The familiar animals can grow up to 6m
Mr Brown added: "There are no rivers or
(20ft) in height
forests to prevent breeding, but some
Their remarkable tongues grow up to 45cm
evolutionary process is keeping the two
(18in) long
groups reproductively separated."
Adult giraffes can weigh in excess of
1,000kg (2,200lbs)
The researchers have suggested these
Long legs enable speeds of up to
processes may be ecological differences,
35miles/hour (55km/h)
such as differences in vegetation at a
macro-level, which are keeping the populations separate or sexual selection.
"The female Maasai giraffe may be looking at the male reticulated giraffe and thinking, 'I
don't look like you; I don't want to mate with you'," Mr Brown explained.
Need for conservation
Mr Brown also highlighted the conservation implications of this study: "Lumping all giraffes
into one species obscures the reality that some kinds of giraffe are on the brink.
"Some of these populations number only a few hundred individuals and need immediate
protection."
Over the past decade there has been a 30% drop in giraffe numbers, with total numbers
under 100,000.
It is hoped that classifying current subspecies as fully fledged species will help inform
conservation plans to save the most threatened populations. These include:
 The Nigerian giraffe (Currently: Giraffa camelopardalis peralta). The last 160 individuals
are found in West and Central Africa.
 The Rothschild giraffe (Currently: Giraffa camelopardalis rothschildi). The last few
hundred can only be found in a few protected areas in Kenya and in Murchison Falls
National Park, Uganda.
The animals' status is currently under review by an International Giraffe Working Group
(IGWG). Its evidence will inform the IUCN Red List of threatened and endangered species.
The genetic research was supported by the US-based Wildlife Conservation Society.