In Taxonomic Limbo
Text: Ian Michler. Photograph: Tim Jackson. Article from the April 2013 issue of Africa Geographic Magazine.
An elephant is an elephant – or could it be a savanna elephant or a forest elephant? It’s not just a question of the name, but a far more serious matter of conservation priorities and strategies.
It is highly improbable that any visitor to Africa, whether on safari in West, East or southern Africa, would have difficulty in identifying the African elephant Loxodonta Africana. It is, after all, the largest terrestrial creature on the planet and its trunk could be said to be the most recognisable anatomical feature in the animal world. However, far more people are likely to be surprised by the suggestion that there may be more than one elephant species roaming the continent.
Throughout the past century, the biological world regarded the African elephant as a single species, albeit with two extant subspecies: the savanna elephant Loxodonta africana africana and the forest elephant L. a. cyclotis, which are separated on morphological differences. The more obvious of these can be seen in the respective animals’ size and shape, and there are also variations in their behaviour and feeding.
But in the past decade, DNA testing carried out by a team of scientists from the Department of Animal Sciences at the University of Illinois, US (www.ncbi.nlm.nih. gov/pubmed/21775678), has shown that there may be far more significant reasons to distinguish between the savanna and forest forms. The genetic evidence at this stage supports a split into two distinct species: the savanna, or bush, elephant Loxodonta africana and the forest elephant L. cyclotis.
Team members have also analysed DNA samples obtained from two extinct elephantine species, the mastodon and the woolly mammoth, and found that the divergence of the forest elephant began at about the same time as the Asian elephant Elephas maximus split from the woolly mammoth – and that was millions of years ago (http://bit.ly/gnfq85).
Given the highly technical nature of genetics and the variances in interpreting results, it comes as no surprise that elephant specialists are still debating the proposed split. In Africa, the African Elephant Specialist Group (AfESG), which falls under the IUCN, is regarded as the ultimate authority and it has declared that the single species classification is still in place. ‘The taxonomic status of elephants from West Africa remains uncertain,’ it reasons. ‘In addition, some populations of high conservation value may consist wholly or partly of interspecific hybrids under a multiple- species scenario.’ The group advocates more research into West African elephants as well as further sampling among key populations within deep forest and outside the traditional Central African ranges, such as those on Mount Elgon and in the Albertine Rift.
A split into two species means that each would be managed independently, with a distinct strategy to match its specific gene pool and habitat, and the threats that face it
In essence, and without getting lost in the complexities of genetics and what defines a species, the problems arise where the ranges of the two subspecies overlap, as it is in these transitional zones that they have interbred – and provided scientists with a quandary. The region where the forest populations of eastern Democratic Republic of Congo meet the savanna populations of Uganda and Rwanda is a case in point. If the offspring prove to be reproductively viable hybrids, researchers will need to determine their numbers and their classification. In addition, any clear-cut delineations between the geographical ranges of the two proposed species become blurred.
There’s more to clarifying the taxonomic status of elephants, though, than scientific precision; there are significant and far-reaching implications for conservation. A split into two species means that each would be managed independently, with a distinct strategy to match its specific gene pool and habitat, and the threats that face it.
The numbers would, of course, change too. Most sources assess the current elephant population in Africa to total between 400 000 and 650 000 animals, and according to the IUCN Red Data List they are spread across at least 37 countries. The statistics are seldom broken down while the African elephant is still regarded as a single species, but it is thought that no more than 120 000 to 150 000 of the estimated total are forest elephants. In the light of these figures, action to protect this form – whether it is regarded as a species or a subspecies – becomes more critical.
The IUCN also lists the African elephant as Vulnerable (it was downlisted from Endangered in 2004). As far as CITES is concerned, it has been in Appendix I (no trade) since 1989, although the populations in Botswana, Namibia, Zimbabwe and South Africa are considered stable and were moved, with very specific annotations, back to Appendix II (controlled trade) in 1997 and 2000.
Herein lies the crux. Although these four countries are home to the majority of the savanna elephants – possibly at least 60 per cent of the total – there are other populations, both savanna and forest, that are still under severe threat. Irrespective of whether these are regarded as subspecies or will be classified as new species in time, it is for this reason that current conservation strategies should already be formulated as if the African elephant were two separate species.
With thanks to Mike Chase at Elephants Without Borders for clarifying the intricacies of genetics
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