By Daily Mail Reporter


Diversity: This Afghan hound, Manny, provides one of the more spectacular examples of canine variation


Dogs come in all shapes and sizes, from towering alsatians to tiny chihuahuas, from shaggy St Bernards to hairless puppies.

But remarkably, every breed of dog is a member of exactly the same species - Canis lupus familiaris.

While some variation between breeds has occurred naturally, most of the very obvious differences are the direct result of human breeding.

Contrast: Oakley the pug and Little Dude, a St Bernard, are members of the same species despite appearances

A feature in the latest issue of National Geographic magazine illustrates the extraordinary diversity of caninekind - and explains how much of it is the result of human activity.

While many dogs nowadays are bred for their aesthetic qualities, in the past there were more practical motivations behind human intervention in the gene pool.

Many dogs were raised to be the best possible hunters - for example, as National Geographic notes, the dachshund was bred to get in to badgers' setts with their low, narrow entrances - hence its name, which means 'badger dog' in German.


Striking: The remarkable appearance of black-haired puli Charlotte is produced by variations in three genes


Distinctive: The Rhodesian ridgeback is famous for the shape of its spine, the result of just a single gene

Unusual: But the hairlessness of dogs like Sugar, a Chinese crested, is down to only one genetic variation

One possible reason dogs are so easily adaptible is because changing their genetic code is relatively simple compared to many other species.

In human genes, for example, nearly every characteristic is governed by a complex network of genes, which work in combination to display certain outcomes.

But with dogs, many quite drastic changes, such as fur type and ear shape, are controlled by a single genetic variation.


Beautiful: The papillon takes its name from the French for 'butterfly' because of the shape of its ears


Protective: The behaviour of Tibetan mastiffs like Midas remains a mystery to scientists

Dogs: The English setter is another breed created by no more than a few dozen evolutionary changes

In fact, a huge research project called CanMap determined that every single biological difference affecting dogs' appearance is controlled by one of around 50 gene variations.

This simplicity is partly a result of the human activity which has tinkered with canine biology for thousands of years, and has therefore picked out the characteristics most easily changed by simple genes.

Nonetheless, there is one aspect of variation among dogs which breeders do not yet know how to control - canine behaviour remains a closed book for researchers.


These amazing images are taken from the February 2012 issue of National Geographic magazine, on sale now



source:dailymail