Environment
How the zebra earned its stripes
Publish Date: Apr 03, 2014
How the zebra earned its stripes
A new study says it is very likely that the stripes on zebras discourage parasitic flies. PHOTO/Reuters
  • mail
  • img
newvision

PARIS - Zebras have stripes to deter the tsetse and other blood-sucking flies, according to a fresh bid to settle a debate that has raged among biologists for over 140 years.

Since the 1870s, in a dispute sparked by the founders of evolutionary theory Charles Darwin and Alfred Russel Wallace, scientists have squabbled over how the zebra got its trademark look.

Are its stripes for camouflage, protecting the zebra with a "motion dazzle confusion effect" against hyenas, lions and other predators in the savannah?

Do the stripes radiate heat to keep the zebra cool?

Or do they have a social role -- for group identity, perhaps, or mating?

But a new study, published in the journal Nature Communications on Tuesday, says the strongest likelihood is that the stripes discourage parasitic flies.

The finding was intriguingly thrown up by lab experiments in 2012 that showed how blood-feeding flies shun stripey surfaces and prefer instead to land on uniform colours.

Researchers led by Tim Caro of the University of California at Davis, say there is no black-and-white answer to the Great Stripe Riddle -- but the insect theory is by far the best bet.

"A solution to the riddle of zebra stripes, discussed by Wallace and Darwin, is at hand," they write.

The team found a strong geographical overlap between zebras and the two groups of biting flies, Tabanus and Glossina, that feed on equid species, which explains why zebras would need a shield against this pest.

There is also plenty of indirect evidence, they say.

Other equid species, such as wild horses, are far more likely to be plagued by biting insects.

Researchers find comparatively little blood from zebras in tsetse flies, even though the zebra has a thin coat with hair strands that are shorter and finer than those of giraffes and antelopes.

At the same time, zebras are far less susceptible to sleeping sickness, a tsetse-borne disease that is widespread among other African equids.

The correlation between reduced biting-fly nuisance and stripes is "significant," says the study.

"Conversely, there is no consistent support for camouflage, predator avoidance, heat management or social interaction hypothesis."

Parasitic flies can hand on a range of diseases when they bite their prey, and their appetite can be enormous.

Experiments with horse-flies carried out in the United States found that cows can lose between 200 and 500 cubic centimetres (0.4 and 1.05 pints) of blood per day to the insects, and as much as 16.9 kilos (37.2 pounds) in weight over eight weeks.

AFP

The statements, comments, or opinions expressed through the use of New Vision Online are those of their respective authors, who are solely responsible for them, and do not necessarily represent the views held by the staff and management of New Vision Online.

New Vision Online reserves the right to moderate, publish or delete a post without warning or consultation with the author.Find out why we moderate comments. For any questions please contact digital@newvision.co.ug

  • mail
  • img
blog comments powered by Disqus
Also In This Section
With rich-poor split, climate talks run into overtime
The UN talks go deep into overtime as negotiators struggle to break a deadlock between rich and developing nations....
Kanungu residents flee as elephants invade
A herd of 10 elephants from neighboring Democratic Republic of Congo has invaded Nyanga sub-county in Kanungu district after crossing River Ishasha....
Eco-stoves clients stuck as refund stalls
The clients, who have now lost hope, suspect that Ecostove Systems staff could have used the idea of a refund to bait unsuspecting customers....
Titles in wetlands can’t be cancelled in one day
The move to cancel titles is aimed at ensuring that the wetlands are protected. The process of cancellation is, however, cannot be done in one day, says lands minister Daudi Migereko....
LDCs may need annual $500bn for climate by 2050
Developing countries may need up to $500 billion per year by 2050 to adapt to the ravages of climate change, the UN says....
NEMA has failed its duty, says environment minister
Kinawataka swamp on the fringes of Kampala city has almost been wiped out and it will take serious efforts to restore it, says the state minister for environment....
What is causing the rise in Early child marriages?
Decaying social structures
Poor Education
None of the above
follow us
subscribe to our news letter