By Matthew Cobb
Okapis (Okapia johnstoni) are the closest living relative of the giraffe (their lineages separated about 16 million years ago). They live in the rainforest of the Democratic Republic of Congo (DRC) in central Africa. Although their bodies are brown, their legs are striped like a zebra’s. They first became known to science at the end of the 19th century.
These animals browse on plants growing in gaps in the forest caused by tree fall – this means that their food is relatively sparsely and randomly distributed around the forest. The precise number of okapis in the wild is unknown (figures vary between 10-50,000), but the overall trend is downwards (an estimated 50% decline in the last three generations). They are already extinct in neighbouring Uganda. As a result, the IUCN to have put the animal on its Red List of Endangered Animals.
The major problems for the okapi are, predictably, associated with humans – logging is destroying its habitat, and contact with humans is leading to hunting for bushmeat. Furthermore, illegal armed groups involved in elephant poaching, bushmeat hunting, illegal mining (gold, coltan and diamonds), illegal logging, charcoal production and agricultural encroachment, all make it difficult for conservationists to operate in the area.
Little is known about the ecology of the okapi because it lives in such difficult terrain. In the 1980s radiotracking of eight individuals suggested that they were solitary, with home ranges that were about 10.5 km2 for males, and 5.1 km2 for females. However, there is little solid evidence for how they live their lives, and how the sexes interact.
That has recently changed, with a new study by researchers in the UK and in DRC that looked at DNA extracted from 208 faecal samples collected in an okapi reserve (see map below). (In passing, hats off to the team for succeeding in this – a while back a student of mine tried extracting DNA from fresh howler monkey turds; we failed dismally.) Once the DNA had been extracted, they then looked at a short parts of the genome that they knew would show variability (these are known as ‘microsatellites’ in the trade). A total of 105 samples provided valid DNA.
The team then did some fancy population genetics to draw a number of conclusions about the social system, the mating system and the dispersal of the okapis they were studying. (Another note in passing: many zoology students dislike both DNA extraction and population genetics – this study shows why both these techniques are important if you want to understand animals.)
Social system: the lack of overlap in genotypes found at the different dung sites suggests that okapi do not form social units, apart from mother-offspring and adult male-female pairings. There was no evidence of large social groups. This was expected, both from previous research, and from the behaviour of other animals that can be heavily predated (in the case of the okapi, by leopards). Because there was no indication of what is called ‘genetic structure’ to the population they sampled – that is, certain genotypes were not found more often in one area than another – the authors conclude that there are no physical obstacles to okapi moving around the region (see also below).
Mating system: The frequency with which the study picked up full and half siblings sugstes that okapi are genetically polygamous (each male will mate with more than one female) and promiscuous (this situation is typical of most mammalian species). However, varying population densities in different regions may mean that it is possible that in some areas males may defend a territory containing several females, although the team found no direct evidence of this.
Dispersal: evidence of dispersal/movement was hard to estimate because they found so few genotypes more than once (in other words, they did not sample the same animal very often – only 13 individuals provided two data points). One male was recorded twice, 25.5 km apart, but the average distance between samples, if this individual was excluded, was 0.337 km.
The conclusion is that the okapi is indeed a solitary beast. They are isolated for most of their lives, having social interactions only while a calf, or during mating. These beautiful animals, which always appear timid and slightly sad in zoos, are solitary and secretive. If we are not careful, the only place they may be safe is in a zoo.
Cool, love these “almost giraffes”.
I love them too – I didn’t realize so little was known about them. Fascinating study.
A depressing thought I had reading this…are there any signs of slowing of the mass extinction event currently in progress?
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The first question would be if there are any signs of a mass extinction. There are some reports on increased extonction rates, but others that question it, I think. If the rates have increased, will they add up to anything like a mass extinction?
It would be sad if the okapi goes.😩
If they can put radio collars on a few of them, they could track their movements and determine the range of their territories.
They did:
My favourite extant mammal! I often wonder how much Sivatherium resembled them (besides the hefty build and fancy crown of course).
Beautiful creatures – I hope we can change the direction of their possible survival. Thank you for the article!
I usually think of them as serene rather than sad when I see them at zoos. Beautiful creatures.
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This kind of non-invasive research is remarkable in what it can yield. I’m glad you added the note about about the resistance of some students and how such techniques provide scientists a fuller picture of critters lives. lives. So, thanks for the abstract of this work.
And, my, what incredibly beautiful animals!
I have been told (by an artiodactyl expert) that an okapi can be killed by feeding it a banana – the gut microbiome is very closely attuned to a diet of leafy greens, and can’t deal with fruit.
Can’t imagine someone doing something so lousy to a harmless animal, but on the other hand, it does remind me a bit of that Monty Python skit.
Mr Creosote, you mean? Do they actually explode if you feed them a banana?
So, why exactly do most students dislike DNA sampling and population genetics? Well, aside from rummaging around in poo to extract DNA I guess. Would it be wise, if I ever get the chance (time+money) to return to my biology studies, to focus on areas such as these to increase my economic desirability? Granted, I’d forsake higher income for field work, but mostly I’d just want to be able to be employed in a career I could be proud of, enjoy, whilst also bringing in a few quid…all while ignoring J. Watson’s claim that all good science is done by the time you are 30, since being that I’m beyond that, I am supposed to believe that I can offer nothing to any field of study.
There is no shortage of people who do DNA sampling and pop gen, though perhaps some zoology students dislike the latter because it is a complex theoretical and math-heavy subject. I, for one, know quite a number of zoology-oriented grad students who work extensively with DNA sampling and population genetics, but perhaps Greg was referring more toward undergraduates.
If you do decide to go back to studying biology (I’m also an over-30 grad student!), I’d recommend studying whatever interests you. That said, having strong computer skills has become absolutely vital, and people who are good with bioinformatics are going to be highly employable for the foreseeable future.
My two experiences with captive Okapi, many times at an orphanage outside of Nairobi and the other in a “safari park” near Santa Rosa CA
is that they are very friendly and affectionate and love to lick the salt off skin with prodigiously long tongues like their cousins the Giraffe
Beautiful!
This reminded me of another rare animal which resides in Vietnam, and may go extinct due to logging etc:(
The Saola, a gentle, reclusive animal.
Hm, interesting, it looks like a deer but is actually a member of the cattle family:
http://en.wikipedia.org/wiki/Saola
All too familiar story of humans being the neighbourhood psycho again, but enjoyed learning about this animal from the post & comments.
Could someone explain a little more about microsatellites? Are these parts of the genome that show genetic variability but are not tied to phenotypic variability?
Very interesting post.
They are short, numerically variable, tandem repeats. They usually consist of a sequence of between 2 and 5 base pairs, that sequence then being repeated several times, maybe more than a dozen repeats.
Their numerical variability is thought to be due to DNA polymerase “slippage” during DNA replication, with associated incorrect base pairing, resulting in duplication, or sometimes excision, of one or more copies of the repeated motif. Their mutation rate is typically quite high.
They are non-coding sequences. At one time it was thought that they were selectively neutral, although sometimes they seem to be associated with genetic diseases, particularly neurodegenerative disorders, and in those cases may be subject to negative selection.
They are used in genetic mapping, DNA fingerprinting, paternity tests, population genetics studies, and probably a host of other things I don’t know about.
I hope this helps.
Interesting. I didn’t realise that herbivores like that could be solitary. I’d always sort of assumed that carnivores were solitary and/or in small groups but that herbivores herded. I guess its difficult to herd that much in a forest.
I’m confused about something.
So many species travel and live in large groups as a defense against predation. (I’m thinking of Caribou, Wildebeest and schooling fishes.) How does living a solitary lifestyle outside of large social groups work as a defense against predation by leopards for the okapi?
Really nice post BTW.
IANAWB (I am not a wildlife biologist), but I don’t think traveling in large herds is an option for large herbivores living in a dense forest. In that case, the opposite tactic–wide dispersal–might actually be the best second choice. (Or perhaps it is even the best choice where vision and line of sight is as limited as it is in a dense forest. After all, it is much easier to smell and hear a lot of animals than just one.)
That makes sense. Thanks.
Reblogged this on Mark Solock Blog.
When I was in Zaire in the 1970s I was lucky enough to visit a forest reserve that had a captive okapi living in a large enclosure. It was very calm and allowed us to pet it. Their hide feels and looks like velvet!
” If we are not careful, the only place they may be safe is in a zoo.”- I wish the, “we” in this statement were people like the readers and commenters here Unfortunately, the safety of endangered species rests in the hands of those who aren’t about to be “careful”- the only reason that bush meat hunters and poachers haven’t already killed every animal in Africa is that, because of the difficulty of the terrain and the inadequacies of their “tools” they simply haven’t been able to, but that is changing.
As something becomes more scarce, its value rises, making the investment in “high-tech” poaching more profitable: where once to kill a rhino and smuggle its horns involved a long foot-trek through the bush, now they just fly up in a helicopter, dart the animal with a tranquilizer gun, cut off the horn, and fly away, leaving the animal to bleed to death. Entire waterholes are being poisoned just in the hopes of catching a few elephants. Rangers and security forces are few and far between, and usually underpaid and also outgunned by the poachers. I despair for ALL the large animals in Africa, and Asia, as well.
Really interesting. Wish I had time to follow up all the comments!
by the way, typo to ‘suggests’ under “Mating system:”…
It had never occurred to me that any mammals were as anti-social as the okapi turns out to be. And their giraffe cousins are less herd-committed than I’d have guessed, though more social than the okapi are. I wonder if this has anything to do with their being the only remaining species of a pretty diverse family.
Really informative post full of new (to me) stuff. Like other commenters, I was struck be the modern research techniques zoology students don’t like, but then the explanations and clarifications in the comments have the ring of truth.
I’m curious about the advantage in the half-body zebra stripes. I would expect some kind of camouflage at work in a pattern like that but if that were the case, wouldn’t it make more sense for the swiped and dark areas to be the other way around? Okapis spend much of their time in grassy areas which would hide their striped legs.
Fun okapi factoid from Wikipedia: Retired Cleveland Browns (NFL) quarterback Bernie Kosar keeps a couple of dozen okapis at his Ohio home!