There are many coat mutations that affect
animals that can make them black, white, or other colors. In the 1950’s,
the commander of the Seneca Army Depot saw one deer with a completely
white coat. He was so inspired by the mystical-looking creature that he
forbade any of the GI’s from shooting any white deer they saw. Today,
there are about 700 deer at the depot, 300 of which are white, making it
the largest population of white deer in the world.
The deer in Seneca were saved by their
striking coats, but
often such a dramatic mutation can be dangerous for
animals. For example, white animals (and people) are more prone to
getting skin cancer and burn in the sun. Often if an animal looks
different from the rest of the herd, it will be picked out by predators,
or can even be outcast by the other herd members. For this reason, the
rare genes for coat variation don’t tend to continue in a non-domestic
population.
Still, when an animal has defective genes
for pigment formation, it’s hard not to be fascinated. The mysterious
black panther and the mystical white tiger capture the imagination, as
do other strangely-colored animals.
To understand coat mutations, first it’s
important to understand the pigment called melanin. This is what makes
skin and fur dark. When you spend a lot of time in the sun, your body
produces melanin to protect your skin from overexposure. When you spend a
lot of time out of the sun, your body breaks down the melanin and you
become pale again, so that you can absorb the vitamin D you get from
sunlight. When you are born, you already have a certain amount of
melanin in your skin in accordance with your genetics, and of course,
animals and humans are affected by mutations.
The various types of mutations include:
Albinism
- Photo Credit: Paulo Brandão on Wikipedia
Albinism is a mutation that causes
an absence or defect of an enzyme that is involved in producing melanin.
Albinos are often mistaken for leucistic animals, which are different
in that leucism causes an animal to lack all pigmentation. The white
deer of Seneca are not albino, but leucistic.
Melanism
- Photo Credit: US Fish and Wildlife Service
The black panther is not a species. A black
big cat referred to as a black panther is one that has melanism, which
causes abnormal amounts of black pigment to show up in the skin and fur.
Most often these are leopards, and you can still see their spots in
certain lights. Melanism has also been observed in other animals, such
as squirrels and servals.
Piebaldism
- Photo Credit: Globaltvedmonton.com
Piebaldism means animals that have large
splotches of color, but the rest is white. Sometimes a piebald animal
will be a dark one with partial albinism, where only parts of its body
are devoid of pigment. Other times, it will be a light-colored animal
with partial melanism, where parts of its body have a higher
concentration of melanin. Patches occur in localized areas of the body
during embryo development.
Abundism
- Photo Credit: Messybeast.com
When an animal has a dark pattern, like
stripes or spots, sometimes an increase in melanin will result in
abundism. This makes the dark markings thicker and more prominent. In
this zebra, the black stripes have overtaken much of the white on the
animal.
Erythristic
- Photo Credit: Messybeast.com
Erythristic animals have an excess of red
pigmentation and sometimes a decrease in other pigmentation. This is an
extremely rare example of a erythristic leopard.
There are many other coat mutations that
result in a wide variety of startling animals. Concentrations of other
pigments produce yellow, blue, and cream-colored animals. For a list of
genetic colors and terms that big cats (like lions and tigers) and other
animals have exhibited, check out http://www.messybeast.com/genetics/mutant-bigcats-terms.html
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