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Why do leopards
and tigers have spots and stripes?
A new study carried out by researchers at the University of Bristol,
tries to answer the question everyone has asked themselves at least
once: 'Why do leopards have spots and tigers have stripes?' They studied
35 species of wild cats and analysed their fur markings, to understand
what makes them have such different patterns on their fur.
 The
researchers photographed different details in the looks of the cats and
integrated them into a mathematical model of pattern development.
The conclusion was that the animals that lived in the trees, in dense
habitats and were active at low levels of light, have the most chances
to be pattern. These very complex and irregular models on their fur have
probably evolved to help the cats have a good camouflage.
This link between environment and fur patterns is quite strong but
after looking at the evolutionary history, we can see that these
patterns can evolve but also disappear quite fast. It also gives an
explanation to why black leopards are common but black cheetahs are
unknown - leopards live in several habitats and also behave differently.
Several environments allow one species to develop original colours and
patterns and to make them permanent in a population.
The explanation linking leopards' patterns with environment is
plausible but it also highlighted some exceptions: some cheetahs have
spots even though they live in open spaces, while the bay cat and the
flat-headed cat, who prefer closed habitats have plain coats. Another
intriguing thing is that out of the 35 species, only one cat has
vertically elongated patterns, that had nothing to do with grasslands:
the tiger. On the other hand, tigers seem to camouflage really well so
why don't other animals have vertical stripes too?
There are still questions to be answered, but this method confirms
Rudyard Kipling's explanation of leopard's spots and the environment
"full of trees and bushes and stripy, speckly, patchy-blatchy shadows".
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