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Dog Breeds
There are numerous dog breeds, with over 800
being recognized by various kennel clubs worldwide. As all dog
breeds have been derived from mixed-breed dog populations, the term
"purebred" has meaning only with respect to a certain number of
generations. Many dogs, especially outside the United States of
America and Western Europe, belong to no recognized breed.
A few basic breed types have evolved gradually during the
domesticated dog's relationship with man over the last 10,000 or
more years, but most modern breeds are of relatively recent
derivation. Many of these are the product of a deliberate process of
artificial selection. Because of this, some breeds are highly
specialized, and there is extraordinary morphological diversity
across different breeds. Despite these differences, dogs are able to
distinguish dogs from other kinds of animal.
The definition of a dog breed is a matter of some controversy.
Depending on the size of the original founding population, closed
gene pool breeds can have problems with inbreeding, specifically due
to founder effect. Dog breeders are increasingly aware of the
importance of population genetics and of maintaining diverse gene
pools. Health testing and new DNA tests can help avoid problems, by
providing a replacement for natural selection. Without selection,
inbreeding and closed gene pools can increase the risk of severe
health or behavioral problems. Some organizations define a breed
more loosely, such that an individual may be considered of one breed
as long as 75% of its parentage is of that breed. These
considerations affect both pets and the show dogs entered in dog
shows. Even prize-winning purebred dogs sometimes possess crippling
genetic defects due to founder effect or inbreeding. These problems
are not limited to purebred dogs and can affect mixed-breed
populations. The behavior and appearance of a dog of a particular
breed can be predicted fairly accurately, while mixed-breed dogs
show a broader range of innovative appearance and behavior.
In February 2004, the Canine Studies Institute in Aurora, Ohio,
arranged recognized breeds of dogs into ten categories.
Mixed-breed dogs or Mongrels are dogs that do not belong to specific
breeds, being mixtures of two or more in variant percentages. Mixed
breeds, or dogs with no purebred ancestry, are not inherently
"better" or "worse" than purebred dogs as companions, pets, working
dogs, or competitors in dog sports. Sometimes mixed-breed dogs are
deliberately bred, for example, the Cockapoo, a mixture of Cocker
Spaniel and Miniature Poodle. Such deliberate crosses may display
hybrid vigor and other desirable traits, but can also lack one or
more of the desired traits of their parents, such as temperament or
a particular color or coat. However, without genetic testing of the
parents, the crosses can sometimes end up inheriting genetic defects
that occur in both parental breeds. Deliberately crossing two or
more breeds is also a manner of establishing new breeds.
Information Source: Wikipedia Dogs
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