Why do zebras have stripes? This
question has been researched and hypothesized for many years. Up
until now there have been four main theories for why one of our
favorite African animals has its black and white coat. The prevailing
theories were that the stripes a) confused predators, b) protected
against biting insects that carried disease c) helped to control and
maintain body temperature, and d) were used as a way of identifying
with their herd. Previous research has focused on testing one of
these hypotheses at a time. The latest study from a team out of
UCLA's department of ecology and evolutionary biology
tested a bigger set of hypotheses against
one another to come to their conclusion.
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| Zebra (photo credit: Angela Sevin) |
The research team, led by Brenda Larison,
determined that the temperature of the area the zebras lived in was
the biggest factor determining their striping pattern. Larison and
others have committed themselves to learning more about the striping
pattern of zebras, with their cutting-edge research including DNA
sequencing to determine what genes code for striping. In this
particular study, Larison's team observed the plains zebra, which is
the most common of the three species of zebra. This zebra has a wide
range of stripe patterns. By comparing sixteen different areas where
the zebras lived, the scientists found that the zebras in colder
areas had lighter, narrower and fewer stripes. Often these zebras did
not have striping on their legs. In the warmer regions the zebras had
bolder striping patterns and the stripes covered their entire bodies.
This is the first evidence that we have to show that the black and
white patterns on the zebras have to do with thermoregulation, or
maintaining body temperature.
Other research, that has yet to be
published, also investigates the zebra's body temperature. Daniel Rubenstein, one of the world's leading zebra researchers, has found
evidence suggesting that the external body temperature of the zebras
is about five degrees Fahrenheit colder than animals of similar size,
such as antelopes. These comparable animals do not have stripes but
are found living in the same areas as the zebra. This study
definitely corroborates the idea of the stripes as an important
factor in thermoregulation in different climates.
It takes a lot of research to make a
determination that is not theoretical in evolutionary biology. There
is no doubt that the prevailing theories of zebra striping do have
some relevance, but having some conclusive evidence based on a
combination of factors is welcome information in piecing together
this evolutionary puzzle.
Read more:
- Science Daily: "Why do zebras have stripes? Temperature counts"
- Royal Society of Open Science: "How the zebra got its stripes: a problem with too many solutions"
- Science World Report: "Why do Zebras Have Stripes? Scientists Uncover the Evolutionary Answer"
Zebra and Animal Coloration Resources
and Activities:
- Plains Zebra- Animal Information
- Purdue Extension: Coloration Exploration Lesson Plan
- Discovery Education: Animal Colors and Shapes
- Kids Discover: African Safari
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