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The Fertile Crescent of the Middle East has long been identified as a
"cradle of civilization" for humans. In a new genetic study,
researchers at the University of California, Davis, have concluded
that all ancestral roads for the modern day domestic cat also lead
back to the same locale.
Findings of the study, involving more than 11,000 cats, are reported
in the cover article of the January issue of the journal Genomics.
"This study confirms earlier research suggesting that the
domestication of the cat started in the Fertile Crescent region,"
said Monika Lipinski, lead researcher on the study and a doctoral
candidate in the School of Veterinary Medicine. "It also provides a
warning for modern cat fanciers to make sure they maintain a broad
genetic base as they further develop their breeds."
Leslie Lyons, an authority on cat genetics and principal investigator
on this study, said: "More than 200 genetic disorders have been
identified in modern cats, and many are found in pure breeds. We hope
that cat breeders will use the genetic information uncovered by this
study to develop efficient breed-management plans and avoid
introducing genetically linked health problems into their breeds."
HISTORY OF THE MODERN CAT
Earlier archaeological evidence and research on the evolutionary
history of cats has suggested that domestication of the cat
originated about 5,000 to 8,000 years ago in the Fertile Crescent, a
region located today in the Middle East. This is the area around the
eastern end of the Mediterranean, stretching from Turkey to northern
Africa and eastward to modern day Iraq and Iran. This domestication
of the cat occurred as humans transitioned from nomadic herding to
raising crops and livestock.
Cats, with their penchant for hunting mice, rats and other rodents,
became useful companions as people domesticated, grew and stored wild
grains and grasses. Eventually, cats also became pets but were never
fully domesticated. Even today, most domestic cats remain
self-sufficient, if necessary, and continue to be efficient hunters,
even when provided with food.
Cats and their gene pools spread rapidly around the world as ancient
civilizations developed trade routes. Unlike other domesticated
species, there has been little effort to improve on the cat for
functional purposes. Instead, development of cat breeds has been
driven more by preferences for certain aesthetic qualities like coat
color and color patterns.
Today, there are 50 recognized cat breeds. Of that total, 16 breeds
are thought to be "natural breeds" that occurred in specific regions,
while the remaining breeds were developed during the past 50 years.
THE UC DAVIS STUDY
In this study, the UC Davis research team focused on:
The researchers collected samples of cheek cells from more than
11,000 cats. These cats represented 17 populations of randomly bred
cats from Europe, the Mediterranean, Asia, Africa and the Americas,
as well as 22 recognized breeds.
Genetic markers called "microsatellite markers," commonly used for
DNA profiling, were used to determine the genetic relationships of
cat breeds, their geographic origins and the levels of genetic loss
that have resulted from inbreeding.
NEW FINDINGS
From the DNA analysis, the researchers found that the cats were
genetically clustered in four groups that corresponded with the
regions of Europe, the Mediterranean basin, east Africa and Asia.
The study yielded many interesting breed-specific findings. For
example, the researchers found that the Persian breed, perhaps the
oldest recognized pure breed, was not genetically associated with
randomly bred cat populations from the Near East, but rather was more
closely associated with randomly bred cats of Western Europe.
In addition, the researchers found that, of the Asian cat breeds,
only the Japanese bobtail was genetically clustered with Western
cats, although it did retain some Asian influence.
Cats from the Mediterranean region were found to be genetically
uniform, perhaps a result of the constant movement of ships and
caravans during the early era of the cat's domestication, the
researchers suggested.
LESSON FOR CAT BREEDERS
The study found that genetic diversity remained surprisingly broad
among cats from various parts of the world. However the data
indicated that there was some loss of diversity associated even with
the long-term development of foundation cat breeds -- those breeds
that provided the genetic basis from which modern pure breeds were
developed.
The researchers note that, given the relatively short time span
during which modern breeds are emerging, cat breeders should proceed
cautiously as they develop their breeds, making sure to maintain a
broad genetic base that will minimize introduction of genetically
based health problems.
More information about cat genomics research can be found on the Lyons lab web site.
Funding for this study was provided by the National Institutes of
Health, the Winn Feline Foundation and the George and Phyllis Miller
Feline Health Fund. Also supporting the study were the Center for
Companion Animal Health and the Koret Center of Veterinary Genetics,
both within the UC Davis School of Veterinary Medicine.
Courtesy: UC Davis News Service
Published: Fanc-e-Mews March/April 2008
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Last Updated: Tuesday, April 15, 2008
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DNA samples of most breeds were obtained at cat shows or were sent in
upon the lab's request by cat owners in the United States. The study
was assisted by a host of collaborators from throughout the world.
DNA, or deoxyribonucleic acid, is the hereditary material in humans,
other animals and plants. It carries the instructions or blueprint
for making all the structures and materials that the organism needs
to function.
They discovered that randomly bred cats in the Americas were
genetically similar to randomly bred cats from Western Europe. They
also found that the Maine Coon and American shorthair -- two breeds
that originated in the United States -- were genetically similar to
the seven Western European breeds. This suggests that cats brought to
the New World by European settlers have not had sufficient time to
develop significant genetic differentiation from their Western
European ancestors.
