I have always been fascinated by the fact that so many animals look similar and yet there are a few that stand out as being very different. By far and away the majority of the ungulates are sort of similar with a long nose, horns and long running legs. Most of the cats look similar although the coat color shows some fascinating variations – spots and stripes in every combination. Then there is a group of animals like the elephant with its long trunk and big ears, the camel with its humps and huge lips and of course the giraffe with the characteristically long neck and legs that just break the mold and are so totally different. Really easy for children to identify and yet being so different makes them vulnerable to human induced changes in the world.
How did the giraffe get that neck?
The discussion on how the giraffe got its long neck has been a discussion point in biological circles for many years, and even now we can’t say categorically how this happened. Darwin argued that it arose through competition with other browsers. The efficient browsers like kudu and impala take the leaves that are within reach leaving few for the giraffe, so encouraging the giraffe to grow long legs and neck to reach those leaves the others could not reach. Observations show that giraffes do indeed bite off more leaves at higher levels where the other species are unable to reach them compared to the amount they get at low levels. However, there is a cost to growing those long necks; those giraffes with longer necks need more nutrients to maintain the long-necked lifestyle and suffer a higher mortality during droughts than those with shorter necks. If you have a long neck and long legs then there are also some big physiological issues you must face – the brain needs oxygenated blood to function, so the giraffe has to have a “turbocharged” heart, the greatest blood pressure of any known mammal and thickened veins to pump the blood to the brain. What is more, they also need special adaptations when they lower their heads to drink to stop the blood rushing to the head. A recent paper by my good friend Doug Cavener compared the genes of the giraffe with its closest relative, the okapi and showed that 70 genes in the giraffe have become specially adapted to allow this lifestyle and many of these genes are involved in cell proliferation and growth.
There are alternative explanations to why giraffes have long necks. Females find males with long necks more attractive and so select these males as the fathers of their offspring. As such the long neck can be considered a secondary sexual characteristic that females select and this can get emphasized over time, much like the peacock’s tail. Intriguingly the necks are used when males fight and if you have ever watched two males fight for dominance the sledgehammer blows they use on each other really consider the giraffe as vulnerable. This means the species is likely to become endangered unless the circumstances that are threatening its survival and reproduction improve and the usual cause of this demise is through habitat destruction.
However, this estimate of the giraffe population assumes we are looking at just one species, and the IUCN have already pointed out that three of the subspecies are in a bad way: Kordofan and Nubian are listed as critically endangered and reticulated as endangered and in need of immediate action. They have been working on the belief that the giraffe is one species with nine subspecies and now, recent research has proposed there should be four species of giraffe and have asked the IUCN to consider this information and the conservation status of each proposed giraffe species and so provide action plans for each species.
To investigate how many species of giraffe there really are in Africa, Julian Fennessey 2 from the Giraffe Conservation Foundation collected DNA from multiple giraffe populations throughout Africa, and for the first time, sampled all nine subspecies including the rare Nubian giraffe from Ethiopia. The samples were then taken to Axel Janke’ lab at the Senckenberg Biodiversity and Climate Research Centre in Frankfurt for the extraction of DNA. Fundamentally, DNA can be divided into two types – the nuclear DNA in the cell nucleus, which is derived from both parents, and then DNA in the mitochondria, an important organelle that sits in the cell and uses nutrients to make energy. This mitochondrial DNA is derived only from your mother, since at fertilization the sperm provides just nuclear DNA for the young embryo and all the mitochondria comes from the mother’s egg. As such this mitochondrial DNA can be traced back from mother to grandmother and back through to the equivalent “eve” without the complications arising when DNA reshuffles with male DNA. What is more, the mitochondrial DNA exhibits an elevated mutation rate, so looking at the base sequence is a very useful way for working out the relationship between populations and species. What Janke and his team did was to separate the mitochondrial DNA and nuclear DNA from the samples and compare them between samples of giraffe. They found several clear signals indicating that the giraffe is not one species but indeed four different species with five subspecies and providing a good explanation for much of the confusion that existed before this analysis. The proposal is summarized in Figure 1 and will identify the southern giraffe (G. giraffa), which includes two subspecies — the Angolan giraffe and South African giraffe found in South Africa, Namibia, Botswana, Zambia and Zimbabwe; the Masai giraffe (G. tippelskirchi), comprising of the Thornicroft’s giraffe subspecies found mainly in Tanzania, Kenya and Zambia; the reticulated giraffe (G. reticulata) found in Kenya, Ethiopia and Somalia; as well as the northern giraffe (G. camelopardalis), found in eastern and central parts of Africa
Dramatic changes like this in the taxonomy of any species, let alone the charismatic megafauna, attract attention from other scientists and it is not surprising there has been comments. While the 195 samples collected for analysis is the first inclusive comparison of giraffe genetics, there is only a handful of samples from the rarer subspecies and so people are warning that the conclusions should not be considered definitive. As such the alternative view is that this is a new perspective on giraffe taxonomy but, as yet, one that should not be accepted totally without further investigation.
The IUCN are currently examining these findings and if they accept the number of new species, they will now revise the listings for every species and this should have a major impact on giraffe conservation action. If they embrace these findings then all of the giraffe species must be protected, and with special attention focused on what will be the status of the northern giraffe and the reticulated giraffe. Each of these species has fewer than 10,000 individuals and numbers are falling fast. There is a parallel here with the African elephant which was originally considered one species and then in 2010 divided into two species: the forest and the savannah elephants and this resulted in increased calls for extra protection.
Much of the threats to giraffe are based around habitat destruction, in particular the acacia savannah resulting in reduced food, but they are still hunted for bushmeat. There are even more sinister reasons why giraffe are disappearing at a rapid rate. In Tanzania, there are reports that people think the bone marrow and brains are a cure for HIV AIDS. Giraffe bone legs are being sold to be carved to look like ivory and in DRC, giraffe tails are used as high class fly swats and are part of marriage dowries. At the end of the day we need to be worried about giraffes; not only are they just so strange looking but they are a critically important species in the savannah ecosystem and in much need of protection and support.
References
1. Agaba, M… Cavener, D. 2016. Giraffe genome sequence reveals clues to its unique morphology and physiology, Nature Communications, 7, 11519
2. Fennessy, J., Bidon, T., Reuss, F., Kumar, V., Elkan, P., Nilssson,. M.A., Vamberger M., Fritz, U & Janke, A., 2016. Multi-locus Analyses Reveal Four Giraffe Species Instead of One. Current Biology 26, 2543-2549
3. Shorrocks, B., 2016. The Giraffe: Biology Ecology Evolution and Behaviour. Wiley 232pp.
What can you do to help giraffe conservation?
1. Encourage a young person to respect and admire giraffes by adopting an orphaned giraffe and giving it as a gift. I did an adoption for my granddaughter through The Sheldrick Wildlife Trust and hope to take her to Kenya so they can meet one day. You can also adopt a giraffe through the websites of the Giraffe Conservation Foundation or the World Wildlife Fund.
2. We know surprisingly little about giraffes (Look at the giraffe book by Bryan Shorrocks if you want more information) so making a donation to one of the giraffe conservation groups is a good thing to do. You can donate to Wild Nature Institute or to the Giraffe Conservation Fund, both of whom are undertaking important conservation research and taking action to protect giraffe.
Talk with them first and find out how your money will be spent and tell them what you want it to support. At the same time you may have skills that could help them, you could donate your photos for them to use or you may have skills with the internet, social media, accountancy, vehicle repair or be keen to lend a hand in the field that could help the running of these foundations – by definition they are run on a shoestring so anything you can do will be helpful.
3. Increase awareness within your social circles and beyond by posting your photos on social media, talking at your local schools and making people aware of the issues facing this charismatic species. Make a big splash on June 21, when it is world giraffe day and use the hashtag #standtallforgiraffe.
4. Giraffes feed primarily on the leaves and twigs of acacia, mimosa, and wild apricot trees and yet these are being destroyed so support tree planting and rewilding efforts in Africa. Organizations such as One Tree Planted, Trees for the Future and the Ethiopian government have dramatic tree rewilding programs that need money for tree cultivation and protection – you can find these all online. Or you can go out and help people plant.
5. Become involved in a giraffe citizen science project if you are visiting Africa. Projects like Zooniverse.com where you record statistics about giraffes and submit them to a researcher who aggregates the results and uses them to improve understanding and conservation.
